"Nutrition for Female Athletes" with Professor Kirsty Elliot-Sale and Dr José Areta

EPISODE 172

[INTRODUCTION]

[00:00:00] LB: Hi. Welcome, or welcome back if you're a regular, to The Institute of Performance Nutrition We Do Science podcast. This is episode 172. And I am Dr. Laurent Bannock, the host. 

Now, today, I had a great conversation. I always have great conversations, of course. And today's conversation was with Professor Kirsty Elliot-Sale, and Dr. Jose Areta. And, yes, you'll know those names if you have been listening to the podcast, or you're a student, or a researcher, or a practitioner in the sport and exercise domain, because these two are leading the way in a number of areas that relate to the theme that we will be focusing on in today's podcast discussion, which is on nutrition for female athletes. 

Now, in the past episodes that they have appeared in, Dr. Areta, for example, we talked about relative energy deficiency in great detail. A leading area of research for Dr. Areta, which of course we touch upon a little bit in this podcast as well, as substrate utilization, and metabolism, and so forth. Four areas that Jose really knows his stuff on. 

And with Kirsty, of course, we talked about female athlete health, female physiology, and bone health and various other things, which of course you can listen about in all these previous podcasts that I will link to in the show notes for this particular episode about nutrition for female athletes. 

Now, look, it's a vast subject area. And what we talked about today was really just the tip of the iceberg in terms of what we can actually talk about within the confines of an hour and a bit podcast, but also as it relates to all the knowledge, all the information, all the evidence on this topic that has come to light and will come to light. And we talk about that in detail. We talk about the quality versus the quantity of that evidence. We talk about some really intriguing areas about what differentiates males from females. Is that even relevant in the context of athletes and performance, and in particular, nutrition? And the many, many nuances that relate to human health and performance, which we of course get into in pretty much every podcast that I’ve ever done, because it's all about context, once again. 

And I won't hold back on that, because that's what we're going to get into. It's all about context, contextualization. Is it relevant for practice being something that I’m obsessed with? 

Anyway, before I let you listen to this conversation with Dr. Areta and Kirsty Elliot-Sale, Professor Kirsty Elliot-Sale, please do go check out our website at www.theiopn.com. It's undergoing a lot of changes. If you've not checked it out recently, you'll see a lot of updates to various parts of the site. We've got a whole new section on the podcast coming soon. But there is still a place for the podcast there where you can find the most recent episodes and access to notes. But all of the nearly 200 episodes, or at least it will be soon, 200 episodes, because I’ve got many new ones lined up that you'll be pleased to hear, will be appearing on the website, too, in a new format. But most importantly, completely updated section relating to our diploma will be there. You can learn all about our advanced program in sport and exercise nutrition practice, our diploma in performance nutrition, which strength conditioning coaches, nutritionists, dietitians, personal trainers, people with or without advanced degrees, PhDs, and so on, are all taking part in our program. 

In fact, you can read about some of their success stories on our new blog on our website where you can see what has happened to a number of our graduates, which we are adding to on a monthly basis. So come back and check that out. And of course, our software SENPRO dedicated to support you in your work as a performance nutritionist or as a sports nutrition-focused practitioner working either in private practice, team settings, group coaching, online, please check out our platform there. It's really unique. And you won't find anything quite like it to support you as a performance nutritionist or as a sports nutrition coach. 

So anyway, that's it. All of that's at www.theiopn.com. Now, here is my conversation with Dr. Areta and Professor Kirsty Elliot-Sale on nutrition for female athletes. 

[INTERVIEW]

[00:04:35] LB: Hi, and welcome back to The Institute of Performance Nutrition's We Do Science Podcast. Now, today I’ve got two guests who've been on before. I love these guys in many different ways. And again, I’ve said this many a time. Half time, I do this podcast as just selfishly because I enjoy talking about this stuff. And these two really know their stuff as it relates to today's focus, which is going to be on nutrition and female athletes. 

Now, before we get into this topic in any further depth, I just wanted to say hi and welcome, Kirsty. Welcome back, Kirsty. And welcome back, Jose. How are you both doing? 

[00:05:14] KES: Good. Thank you. Honestly, thanks so much for having me back. I love coming on and chatting with you. And yeah, trying to sort of unpick some of these topics with you is always fun. And we always get something interesting out of it. So, yeah, thanks for having me back.

[00:05:28] LB: Yeah. Well, no, thank you. And Jose, I’m ashamed I’ve forgotten what podcast episode numbers. I should be super prepared and start firing them out. But as I said, you've both been on here a number of times in various capacities. And Jose, you've stayed put where you are in Liverpool John Moores. But why don't you just give us a quick overview as to what you're doing and where you're based, etc. 

[00:05:53] JA: Yeah. Thank you so much, Laurent, again for this invitation. It's a pleasure to be here with you again. Yes. As you said, I’m based in Liverpool since like – It's going to be four years now. I can't believe it. It's gone so quick. I suppose that's a good thing. 

Yeah, I’ve been here since sort of slowly focusing my research more in the area of low energy availability. Sort of making it one of my areas of research. But of course, I’ve done some applied work. And we currently have some lines of work in female nutrition and and so on. 

So, of course, one of the focus of my research has been around like muscle glycogen, which is sort of a topic that I always really, really like. So we're still doing some research in that area as well. So, yeah, thanks for inviting us to talk about this sort of special edition that we did there with Kirsty in the European Journal of Sport Science. Really a pleasure to talk about this.

[00:06:47] LB: Yeah. That's great. Well, I can't wait to delve into this this topic with you guys. And Kirsty, of course, you're newbie to this this podcast. We've talked about all sorts of things. Although it is always been related in one form or another to female physiology or female sort of nutrition requirement. So there has been a consistency there. And we'll sort of evolve that a bit further in today's conversation. But you've moved. So why don't you just tell us about that? Because there's some new – You've got news, which not everyone will know, I guess.

[00:07:17] KES: Yeah. So the news headline is that I’m moving to Manchester Metropolitan University, so, MMU. And yeah, joining the new institute of sport there, which is super exciting. And yeah, in this position, I’ll be sort of driving the research agenda in female athletes. No surprise there. 

So, you're right. Every time I come on, that's my topic. Like a broken record. But hopefully, as I say, I always pray, try to bring something new to each conversation. And it's certainly an evolving area. It's a really dynamic evolving area. A hot topic, of course, right now, particularly in nutrition. Yeah, it'll be interesting to speak about some current controversies or ways in which we can improve this area. So, yeah. So, new digs, new place, but still same area of research. And I’m really excited to get stuck into that at MMU in the new institute. 

[00:08:11] LB: What I find quite interesting about what you're doing, for example, is it does illustrate the level of movement and change that obviously is happening to you personally in your own career, etc. But also, in the industry in general, we are seeing quite a lot of sort of development and movement as it relates to increased research. There're new departments popping up here and there. Not just obviously in the UK, but globally. There are some countries that have, yes, lots of great research facilities in sort of medical public health and so on but have not necessarily been that invested in human performance or particularly sport and exercise nutrition. We're now starting to see that in all four corners of the world. Although, it is fair to say that the UK is still a significant stronghold for this particular area of sport and exercise science. 

And both of you are significant contributors, of course, to that work, which I guess there are several areas that are particularly topical right now in performance nutrition and sports science, sports medicine, and so on, which of course is female health, female nutrition in particular. And definitely the whole sort of energy deficiency topic has exploded in the last number of years. 

And it's been great to have you both on actually in your separate capacities talking about these topics, which I’ll reference in the podcast, as well as other guest experts that have come on to talk about this stuff. But it does just blow my mind, even after all these years now that I’ve been doing this podcast, just how stuff is going on in our field. And that's great, I guess, for both of you, is that it remains exciting and motivating even if we do have pandemics and various other things that are going on.

Just quickly, because while I’m on this topic, I know you're both – You're at a powerhouse for sport and exercise science research, Jose and Kirsty. You've been also very much at that forefront in your past institution. And where you're going with this new opportunity is just mind-boggling. But where do you see this going? 

I mean, do you think we're in a state of sort of explosion in this area? Or do you feel we're still not at the forefront where we should be perhaps relative to other areas of sport and exercise science given the growth of sports psychology analysis, that sort of thing? Kirsty, I’ll ask you that one first. 

[00:10:40] KES: Oh. That's a big question. 

[00:10:42] LB: Not political. We'll avoid any political – 

[00:10:44] KES: No. Absolutely. I definitely think we're moving in the right direction. So, I do. I see a huge increase in the quantity of research being conducted in, I guess, female athletes in general, or sort of female physiology, female sport and exercise science. But also, in female-specific nutrition. 

And so I think that's been driven by a number of things. I think having reached pretty much parity in the last Olympics in terms of female participation, I think that's really changed the landscape of how academics and practitioners are now sort of honor-bound to put as much effort into providing that support and evidence-based practice to female athletes as they have done for males in the past. 

So, yeah, I do see a lot more quantity. Oh, God. You know what I’m going to say. I’ve only just started, but here she goes. Unfortunately, I still think we're lacking a little bit of the quality. And rather than sort of go into some sort of negative rant, as I have sometimes done in the past, I think what you've just described, this evolution of sport and exercise science, sport and an exercise nutrition, I actually think you've hit the nail on the head there with female-specific nutrition in so much as, historically, we've not taught female-specific physiology, nutrition, at undergraduate level.

So, therefore, in a way, it's not too surprising that there isn't sort of a wave of high-quality female-specific research. Because, actually, how do you go about doing high-quality research if you don't have that underpinning sort of knowledge or that underpinning training? 

I think pushing it all together, I think, yeah, there's an evolution now coming at universities. I see female-specific topics, modules, creeping into the curriculum undergraduate. I think you're going to start seeing a lot more masters, specifically into the female physiology, female nutrition. That's really going to change, I think, the landscape. 

Of course, we see PhD students, and myself included, although 20 years ago, then focusing in this. And hopefully we'll get a new generation of well-trained sport and exercise scientists, nutritionists, that can then take that into high-quality research. 

So I’m not going negative today. I’m going positive. There's a big increase in quantity. And I think the quality will come if we invest in the entire network and area and not just obviously push that on to research. I think it's got to be going an undergraduate level the whole way up. 

[00:13:09] LB: Yeah. It's not negative. I understand why you say that. Because so many previous guests have said the same thing. And we're going back years. I go back all the way to quite a few years ago where John Hawley was on, Professor John Hawley, and he was talking about his concerns about the lack of sports science, sports nutrition research that's done from the perspective of an integrative physiology or integrated biological approach to reductionist, all that stuff, which we won't spend time on now. But making sure that what we're doing is relevant to the people that we're trying to advise as practitioners is central to what is called evidence-based practice, or I prefer evidence-informed practice. But either which way, what we're questioning is evidence. 

And yes, there's the quality of evidence. There's good, bad the quality question there. But the ability to contextualize that information to make it actually relevant to the context, the situations that you're dealing with, is something that we've barely started to do, of course. And that's really what you're saying. And that can only be for the benefit of practitioners. 

[00:14:19] KES: Yeah, absolutely. I mean, I think, with high-quality evidence comes confidence for practitioners to take that information and to translate it into their practice. And I think that's really, really important. So I think in the female space, particularly in nutrition, what we want to see are a number of well-conducted sort of laboratory studies that show findings that are in the same direction and of the same magnitude. 

Because, again, I’ve said this in the past. Sometimes, particularly with social media – And social media can be great. Actually, I’m a big fan. You know that Laurent. I do. I really love Twitter. But as a practitioner, particularly at the elite level, would you want to change your whole practice based on one study? Probably not. 

And I think, recently, in research, everybody's looking for novelty. And I’m like, "Hang on a second. Actually, let's have some confirmatory studies. Let's have a number of studies showing a change in the same direction of a similar magnitude so we can go back to the practitioners with a little bit more confidence and say, "We're seeing this now on more than one occasion. We're now finding this is a predictable response. You can take that into your practice." 

Actually, I think more – So, now than ever before, I see a real relationship now between practitioners and researchers. And personally, in my own career, I’ve closed that gap a little bit, because I’ve been guilty of it. First ten years of my career, very academic, very laboratory-based, very reductionist. And it's only in the last five to ten years, thankfully, because I think practice and practitioners have approached many athletes. And it really increased actually the quality of my research. 

I think sometimes people are afraid if they try and work with practice. That means downgrading their quality. But actually, it's really increased mine, because it makes it – It increases the real-world application and so on. So, yeah, I think more so than ever now, this is the way that we can move forward together.

[00:16:14] LB: This topic, this idea of quantity, quality, we'd swing across to cost to benefit type conversations as well. Again, I use the word evidence-based practice. And a key to that is ensuring that you are meeting the needs and the preferences of your individuals that you're working with. Even if it's a team, it's still a team of individuals, right? 

And what we're going to talk about here is going to be very relevant to this idea of quantity, quality, relevance and so on. So I bring this across to you, Jose, because I think the opening line of the abstract of the introductory article in this special series that was published on nutrition for female athletes, what we know, what we don't know, and why? Which I’ll link to all of this. And I’ll just paraphrase this, because I’ll read this out, because I think it's just such an important mind-boggling statement if you really think about this. 

So, men are often considered as the default sex for studies in sports nutrition. In fact, most of the seminal work today in sports nutrition has been exclusively conducted on male participants, right? 

So that's mind-boggling when you do consider just how many athletes we have that are elite. And even, that we can break that down to actually elite and maybe college elite, but not necessarily Olympically. Old, young, all the different types of sports, this, that, and the other. But obviously we come to this point of gender, male and female. 

And yet so much of this being generalized in sports nutrition where we talk about muscle protein synthesis. And we don't talk about the muscle belonging to a male or a female, or to an older or younger person. Obviously, we've started to do this now. But it really starts to become quite interesting. 

Jose, why don't you tell us then why that opening statement is so important? And I guess, just generally speaking, why this special edition became necessary in the first place in this day and age, 2022?

[00:18:19] JA: Yeah. Thank you for the question. And I think maybe the answer in the first instance is my love maybe for philosophy and the existentialist in particular. But that's a statement of Simon de Beauvoir that says that men, or man, is considered default, while woman is being considered like the other. 

I think this is important because, historically, it's been sort of societal norm where how things have been thought, and how through time, this has been changing. And I think that what we see now in sort of sports science and sports nutrition and so on is a consequence of a lot of other changes and sort of more society level. And it's not the only area where we see this change. 

If you, for example, focus on more like medical research as well, this is happening exactly the same thing. It's just a different area where the same thing is happening. So why this is important today, as Kirsty said before, is that in 2021, in the 2020 Olympics, there was almost parity in terms of participation of males and females, which this is a huge difference from what it was in like sort of 1900s, which was like two percent participation of females. 

But the research specific in female is still very much lagging behind where there's six percent of the research use female participants only. Like the more relevant research in sort of sports science. If you look at research that uses like both males and females, it's about like 31%. But when you look at the total amount of participants that have been researched in this sort of sports science area, it's still about like around or 34%, 35% of the total amount of participants being female. So we're still very, very far behind in terms of like characterizing the – I think, Kirsty would be better place than myself talking about the sort of more female-specific physiology and knowledge in terms of like females. 

But definitely, when it comes to sports nutrition, one of the things that we wanted to do with this special edition was highlighting maybe what we know and what we don't know on what we think are pillars in sports nutrition. That's why we selected a range of topics, of things, as important as substrate metabolism. Going through like hydration and energy availability. Making way supplement use and gut health. All the things that we think are all very important that basically form the foundations of sports nutrition. And why we wanted to do this was not only to try to showcase whatever new research there was out there, but also – And more importantly, highlight, there was not there or what we think this should be there in terms of like knowing what should be specific for females and what is not.

[00:21:23] LB: So what's coming to me at this point is something that I think that we should discuss before we really get into, as you say for the title here, what we actually know, what we don't know, and why, right? So I want to get into that. 

But before we do that, I think it'd be worth if – And, Kirsty, I’m going to throw this one at you. It seems ridiculous to have to ask this question. But I think we actually need to define what we actually mean by a female athlete. I hear myself saying that. It's like that's funny, but it's not. Because it's important that we actually do that. And then I think we can go from there on the basis that my second sort of point of that would be that, do we have more in common as human beings? Or is there, on a basic level, which of course we're going to unravel, this concept of being male or female. At what point does that actually become relevant just on a on a general level? Because obviously we'll unwrap that.

[00:22:20] KES: Great question. Huge questions. And as you say, an unusual question. It's not, because I’ve been really questioning publicly, which, yeah, I’ve had mixed reactions to this. But I’ve recently been asking researchers what did they mean by a sex different study? So there's a question. And people are like, "What do you mean by that? Well, that would be male, female, men, women." And I’m like, "Okay. I get that. I do get that." But my question is, "But which woman do you take to compare to the man?" And I think that then really relates to the question you've just asked me.

So, yeah, you can have sex different studies, where you really just take – It's the most simplistic division, isn't it? You're a man. You're a woman. And we'll compare some response, okay? And as I said, I still haven't got an answer to my question. And I’ve never done a sex difference or a sex comparison study. And if I were to, I don't know which type of woman I would choose. 

So here, let's unpick which type of woman I would choose, because that maybe sounds a little odd to some listeners. So if we take women, the interesting thing, what I think is very interesting, the interesting thing about women is this sort of almost, or potentially almost, constantly changing hormonal profile or hormonal status.

So both, of course, males and females, go through puberty. And we get that. So that's in common. So up until puberty, if you were working with children, you could treat them the same in most respects related to sport and exercise, science and nutrition. At puberty, of course, that's the big change. The big change. 

Of course, I’m not going to talk about male physiology. But, of course, an increase in testosterone, X, Y, Z. Okay. Let's look at women. Women, the thing that happens is the instigation of the menstrual cycle. Okay? So that would be considered, I guess, in some ways, to be the body's default setting. So you transition through puberty and. The aim is to lock-in a menstrual cycle. So a predictable pattern of changes in estrogen and progesterone. And of course, they're there to facilitate pregnancy. So that's what the aim is. 

And so then this is where it gets interesting. We must be really careful in sport and exercise, science and nutrition not to think that the default setting for all female athletes are menstrual cycles. They're not. So you do. Everybody starts off by hopefully getting the menstrual cycle. When the menstrual cycle is, there then of course there are choices or there are conditions to that. 

So some athletes might choose to use hormonal contraceptives. And then that completely wipes out that repeating pattern that we see in the menstrual cycle, and it gives a significantly different hormonal profile. So that would be for me. If we're taking menstrual cycle as one group of women, the next group would be hormonal contraceptive users.

Now, I won't go into a big monologue about all the different types of hormonal contraceptives, but just for the listeners to appreciate that we're calling that a group, but there are many different types. There's a lot of diversity within that group. But they're the second I would say biggest group of women. 

Then the sort of third group that we would need to consider when we're thinking about post-puberty, sort of adolescent and adult women, are those with menstrual irregularities. For example, if puberty didn't go as expected, there could be primary amenorrhea. So we don't get that menstrual cycle and menstruation. We have a menstrual dysfunction. Or it could be athletes who have had a menstrual cycle, and then for whatever reason have some sort of menstrual irregularity or dysfunction. 

So amenorrhea, again probably, secondary amenorrhea, is the one that we'll talk about a bit today potentially linked with low energy availability. But there are others. So there are luteal phase deficiencies, and ovulatory cycles, X, Y and Z. And a little bit like hormonal contraceptive users. Let's just say that menstrual dysfunction is the umbrella term for the third group of women we should consider. But there's a lot of diversity in there.

So they're the three biggest groups we'll see probably in an athletic population. So it goes back to that, when we make a sex comparison, who should we compare the men to? Menstrual cycle? And if we use menstrual cycle athletes, which phase of the menstrual cycle? Okay? So although it's a 28-day cycle, we could say that there are six distinct phases there. So is it that group? Do we compare them to hormonal contraceptive users? Do we compare them to those menstrual dysfunction? 

I will mention two other groups quickly. If we're talking about adult women, of course, we could throw in pregnancy as another group. Okay, probably less common in really elite sport. Although, luckily, we're now seeing more female athletes participate longer during their pregnancy and return quickly following pregnancy. So I think nutrition practitioners will have to consider that group, too. And then if you work with sort of older or master level athletes, then the menopause is yet again another different hormonal profile. 

So let me pull that back into maybe one summary sentence and answer to your question. Which type of female athlete you have? That needs to be – They need to be profiled. And I would say the biggest groups are those with menstrual cycles, those that use hormonal contraceptives, those with menstrual dysfunctions, and then less commonly, pregnant athletes and postmenopausal athletes. And that has to be stated, because that's the population you're taking into your research or into your practice. 

And given they all have significantly different hormonal profiles, a from each other, and then b from men, that's I think the thing that we have to consider when we try to make female-specific recommendations.

[00:27:58] LB: And, of course, there's going to be not just differences between those groups. But there's going to be significant within group variation, too. Isn't there? 

[00:28:07] KES: I didn't want to throw your minds even more. But that is the thing. So as you rightly say, we have between sex differences. We have between women or between – Yeah. It's indelicately phrased, but between women. But we also have that within an individual, within sort of female themselves. 

For example, a cycle length can change from 27 days. Next time, it's 31 days. And the next time, it's 34 days. So you can have that. Or you can also have – Within a woman, you can go from having a menstrual cycle to next month starting to take an oral contraceptive pill. Taking it for three months. Stopping it. So it can be quite – This sort of variability is huge. So yeah, we're looking at between sexes, between women, and within an individual woman. 

And so, yeah, we definitely – There is a level of complexity there. But it goes back to our original point. If we educate people about all of these things, then we'll do better in the future. So it is changing the landscape almost if I can sort of take a sporting reference. But we need to start grassroots here and change it the whole way through before we really see top-class evidence-informed practice for female athletes.

[00:29:20] JA: Regardless of the comparison, I think we can all agree that women are not small men. 

[00:29:27] KES: No. No. Of course. That's true. Because, actually, from a nutrition or a physiology perspective, we would just deal with that with scaling. We would just change whether it was the amount of protein. We would scale that relevant to lean body mass, etc., etc. 

So, no. I mean, I think that that whole set of saying is very, very obsolete. I think, for me, it's not a size difference. It's very much a – For me, of course, and it's only my viewpoint, it's driven by the changes and the diversity of hormone profiles. But if I got a psychologist in here, Laurent, they would then be talking about, again, those differences between sex and sort of more psychological outcomes. But yeah, size doesn't matter at all. There we go. Let's put that out there. 

[00:30:09] LB: Yeah. I’m not going down that conversation. But what I do want to say is, because my interest in this is very much about where we get information from that influences our practice, and how we fundamentally impact our clients and subsequently the rest of their careers, their lives, and so on, beyond just their health, obviously, which is clearly the most important thing, which is rooted very much into what we're going to talk about today. 

But, Jose, the reason why I’m interested in this is because we're talking about what we know now. And we're talking about how these factors will add to the filtering mechanisms of the lens that we use as scientists, researchers, practitioners on these sorts of topics as it relates to females. But we've got to go back decades of sport and exercise science research, and there's all this stuff that we've just assumed about nutritional needs for people. What constitutes as roughly the right amount of protein that an athlete should have to support muscle protein synthesis? 

We've got a whole range of advice that's coming out for carbohydrate needs, glycogen restoration, that sort of thing, and obviously an area that you're particularly familiar with as an expert on low energy availability. How do you deal with that when so much of what we now know is based on reference man and not reference woman, whatever that is anyway? 

[00:31:46] JA: That's a very difficult question to answer. So to put things in context a little bit, and as you say, we need to go back a little bit in time and pretty much to the sort of birth of sports nutrition as a discipline, which is these studies that were carried in the 60s in relation to diet and physical capacity, where it was very, very clearly shown that muscle glycogen content was directly related to the capacity to do work at higher intensities. And I suppose that's what triggered the whole interest, and like what can we do with diet to make performance better? So that's sort of the origin of it. 

It's not that this hasn't been studied before. Is it like probably late 19th century that things were already very clear in terms of relationship between diet and substrate use and so on? But in the 60s and so on, became very, very clear. 

And as you are saying, all the research there was carried – Conducted by men. All the participants were men. And that's what sort of became sort of the norm without even – If you read these studies, I don't think there's any reference of like, "Oh, maybe in females." For whatever reason, this is different. For whatever parameters you want to consider, from anatomical differences, to physiological endocrine differences, can this have an effect on it? 

Of course, there's a lot of commonalities between – I mean, we're both still human regardless of the sex or gender. But it's important to still realize that there's a lot of commonalities between the two. So it's not that when one is from Mars and the other one is from Venus. But there are differences. 

To what extent these differences can make a difference in terms of improving performance or changing the sort of physiological adaptations to training? And I think this is what we are able to highlight in this special issue that we co-edited with Kirsty, that we still need a lot of evidence to prove that men and women are different in certain aspects. 

So far, I don't think we have all the experts that we invited to this to write the papers for this special issue. What they highlight is the fact that, well, there seems to be – There's clear differences in some aspects in terms of like physiology, and endocrine, substrate use and so on between males and females. But the common message seems to be that we still need more evidence to be able to make evidence-based recommendations. 

So far, with the evidence we've got for the majority of the aspects related to sports nutrition, we don't have a very clear base of evidence to say, "Okay, women should be doing something completely different to men." But there are definitely differences. And probably, we're going to touch on the area of low energy availability before. But this is one area know that's been – It's probably the only era. There's been more study in females than in males. But we know that women are seen to be more susceptible to the effects of low energy availability than men. This is something that you have to be particularly careful when you're working with female athletes, for example. 

[00:35:07] LB: Yeah. And I guess some of this is a question of where in this sort of maze this puzzle do you start? Do you start with the person I’m advising is a human being? Do I start with they're a female? Do I start with they're an endurance athlete? It gets complicated, particularly from a practitioner's perspective, especially when the reality is, is in practice, there is a limit to the amount of time you might have with an individual. Okay, in private practice you can have no end of limits on your time. But in a team sport setting, whether it's a cycling team or a football team, there can be distinct limits to the amount of time that you have to understand the nuances that makes up an individual, particularly when we talk about things like low energy availability or the differences in hormones, which isn't necessarily as easy to determine just in a five-minute conversation or a quick look at somebody's diet that they've told you essentially what you want to hear. Not necessarily what it is that they're actually doing. 

Kirsty, you talk about quality and quantity of studies, which I think is central to this, because we're talking about things. How much confidence can we have in this information? And how much significance should we put into that to put all our trust in when it comes to following this path? What are your thoughts on that? 

[00:36:36] KES: Okay. So, yeah, I’m not going to put any punches here. So I would say that, right now, today, there are currently no evidence-based guidelines that are fit for purpose to take into an applied setting. There's just not sufficient high-quality information to write the guidelines. So I think that, for me, that's fact. 

And so I think what we have – We've got to find a way to move forward, right? We can't just say to our athletes, "Okay, let's just all stand still and wait for researchers to throw out these high-quality studies." I think we have to do sort of something in between. 

So I would still say that you should feel for the demands of the sport. That's what I would go with first. Because you were saying, "What do we do? Do we go with the human? The sport?" I would still go first, I guess, a more human stroke sport priority first. 

So in the absence of that high-quality evidence, I would say fewer for the demands of the sport, which in a way the concept that is sort of sexless. So we think that this sport demands this. And therefore, that would be a good sort of guiding principle. 

I think then the next layer down, when we want to come to something that's more female-specific, I think there are two ways to look at it. And so up until now, I think our conversation has been looking at, I guess, a biological or a sort of physiological pathway. If you change estrogen or progesterone, it sort of link to a change in substrate metabolism and any aspect of sort of physiological functioning. But that's only one way to look at it. 

The other way to look at it is, if you change the concentration of estrogen and progesterone, they lead to, often, symptoms and side effects. And they can be, again, physical or sort of more emotional psychological sort of symptoms and side effects. So it could well be actually that we're looking at a change in estrogen causes fatigue, or causes anxiety, or causes cramps, or headaches. And actually, it's those things, those symptoms and side effects that limits a person's ability to train and compete. 

So when we look at it, we need to look at it two ways. Sort of this direct biological pathway. This hormone doesn't have this effect on substrate metabolism, for example. Or does this hormone have an effect on how we feel, or the perception of work, or intensity. And therefore, that has a different outcome. 

I think taking all these things together, how do we move forward in the space right now in the absence of these sort of high-quality research guidelines? I would then go to the lived experiences of the athletes. So even if you have five minutes, or ten minutes, or an hour with that athlete who's in front of you, I’m talking specifically female athletes, go in with your fuel for the demands of the sport. But then go into sort of the nuances of being female. Ask them, "What hormonal profile are you?" "Oh, I’m menstrual recycle." "Okay. Do you have any symptoms and side effects each month? Is there a particular time of that month where you notice this always happens to you, X, Y and Z?" And then you can start to maybe tailor some of your nutrition. Make nuanced adjustments to, "Well, at this time, when you feel fatigued, we're going to go with this nutritional strategy." 

So I think asking them about their lived experiences is really important. So asking them which hormonal profile they are. Asking them, is there something predictable? And we tend to see that pattern recognition is specifically relevant for menstrual cycle. 

The other two groups – So those are menstrual dysfunction. Because of the dysfunction, it's hard to see a passion. Again – And I’m going to sort of link the dysfunctions to two things, like low energy availability. There, you're looking for a nutritional strategy, which gets them out of low energy availability. 

Come on. Let's face it. That's the end goal there before we start to look at changes in nutrition that might affect performance. The priority there is to get them out of low energy availability. And then with hormonal contraceptive users, again, there's not really going to be a pattern there, because their hormonal profile is fairly stable. But it's looking to see, again, if they've got any sort of symptoms or things associated, negative connotations with their hormonal contraceptive use and seeing if you can use nutrition as a strategy to overcome some of those. 

Of course, there may be positives associated with their hormonal profiles. And if you can again see those, then maximize that with any strategies. So I would say, right now, take home message, no fit for purpose evidence-based guidelines right now because of the lack of quality and quantity in research evidence. But all is not lost. Go to the lived experience of athletes. Work with them to see patterns maybe linked with their ovarian hormone profiles, and do that. 

Now, one more thing I’m going to say on this point. Not all women are affected by these hormones. Actually, don't look for a problem that might not exist. It may well be that for many female athletes, they can take the same nutritional strategies as men. So just be careful. We don't need to blanket all female athletes and say, "You all have problems. You only fix it. You all need something female-specific." Many don't. And so just recognizing that I think is very empowering. 

Do a little bit of work with them. It will come out in their lived experiences. If they're not affected by things that we consider to be female-specific, so the changes in hormones, leave them alone and go with the other guiding principles. But if they do have lived experiences, which maybe have got patterns or are particularly bad at a point, then we can look to intervene, as you say, on an individual basis. Because even in a team sport, they are still individuals.

[00:42:04] LB: Yeah. And that's fascinating. That is. Because the danger, of course, is prejudicing our assumptions of an athlete's needs on the basis of their gender. It's dangerous, isn't it? Because they might not. Of course, you've now made it even more complicated. 

[00:42:21] KES: Well, I hope – Well, maybe I have. Yeah. I always end making it more complicated. But I sort of want to give people the freedom to recognize that this isn't for all female athletes. And actually, given the diversity in hormone profiles, it may well be – We might never get this universal blueprint, this universal guidance that we can give to female athletes because of that diversity. Because we're not going to have a male rule book, a female rule book because, we said, of all those different categories of females. Does that mean that we need like 10 different books for 10 different profiles of women? I don't know. Maybe we are adding too much complexity. 

I think the likelihood is, and I think Jose sort of mentioned this earlier, we don't have to throw the baby out with the bath water, as the saying goes. A lot of the principles will hold true. A lot of what we know will be true. But it's the nuance differences that we can make. And those little sort of marginal gains. And I know not all sort of people who work in the high-performance network like that term. But marginal gains are very important at the elite level 

And so for a female athlete who maybe does have a particular phase of the menstrual cycle where something is not at its optimal level, and we can do a strategy, that could be the difference between the podium and not, or gold and bronze. And so I think it is worth continuing to dig in the lab and pull on that string. And also, by listening to the lived experiences, because actually that could make a big difference. 

But yeah, there's a lot to consider here. And although I don't want people to switch off or be overwhelmed by some of this complexity, I think if you don't consider the complexity, then you're going to end up whitewashing, being inappropriate, trying to do a one-size-fits-all. And that will not work here. One size will not fit all when it comes to women. 

[00:44:10] LB: Yeah, I guess we need to bear in mind that the bigger picture from the sort of the guiding principles, sound sensible guiding principles of nutrition advice for athletes, is still going to be the sort of the total type and timing type of perspective. We've very much got to individualize based on needs, preferences, circumstances and all these other things. 

But there does come a point where these nuances, as you say, can become the influencing factors in a degree of success or failure in training outcomes, or in particular, performance outcomes in certain people, which I guess is more likely to be in the elite, more extreme ends of that area. 

But Jose, in this collection of papers, there's some fascinating – They're all fascinating papers, whether we're looking at substrate, metabolism or specifically fueling strategies for female athletes, the whole concept of low energy availability. We've done a podcast with you all about that, of course. And Kirsty, we've looked at female athlete health. Not just performance, but health. We looked at bone health and so on with your partner in crime, of course, Professor Craig Sale. We've done podcasts about that sort of thing. Yes, of course, we have to consider supplement strategies and so on. But of course, I don't have it in front of me now, but the paper on making weight. An area that I find particularly fascinating in female combat athletes, for example. A point was made by Carl Langan-Evans at all in there about we still need to individualize everything to the individual, of course. 

But, Jose, there are a number of things that when you read through these different papers that stand out. And I guess there's the varying hormonal sort of influence on things like potentially substrate metabolism or so on I think does start to get rather interesting. What are those areas with things like substrate metabolism and energy availability that you find so fascinating, particularly in female athletes, Jose, in your own work? 

[00:46:15] JA: Well, I think that that's a great question. And this comes down to my liking, I suppose, the question that you're asking me. But I think – And this is to underscore what Kirsty mentioned before, the importance of fueling and sort of the physiological implications of not fueling properly. 

Of course, we are having an approach here that is purely sort of physiological to the matter. We know that, really, it's a lot more complex than that when we are working sort of the real world with athletes on how to put through the message of what is the right thing to do. 

What I really find fascinating reading my own area of work is how sort of not feeling appropriately can have a sort of very deep endocrine and physiological effect on how we are in sort of addressed and how we respond to training. And how this affects performance, of course. 

One of the things that is very, very clear, and this is very much related to my area of interest also in massive glycogen, is the importance of carbohydrates for performance. And this is, again, along the lines of what Kirsty was mentioning in terms of fueling. 

It's remarkable the mismatch between exercise energy expenditure and energy intake particularly in sports with high-energy demands. And I think one of the things that I find interesting is how most athletes really don't feel the way they need to be able to keep up with their training. And of course, this is a quite complex area because we know that sometimes we need to withdraw a little bit of energy to adjust body weight and body composition to certain sort of type of needs. But also, we need that fuel to perform at our best. 

So it's very much a balancing act, this complex. I think, in general, it's been thought as a very much a black and white sort of area where like energy balance sort of the thing that should be achieved at all times. And energy deficit is this evil that needs to be avoided. 

And I think what I find fascinating is that reality is a lot more colorful. And I think we have to dive into these nuances and understand the complexities of it to make the right choice at the right time depending on what the demands are of the athlete, and the sport, and the sex or gender, or a lot of things that have to be considered to be able to make the right choice. 

But as a general rule, I think going back, again, to fueling. I think this is one of the things that, even though it's so clear that carbohydrates are important particularly for high-intensity – Sort of this high-intensity parts of any sport pretty much. And we know that most sports are won in moments of any sort of winning move is related to high-intensity. We need those carbohydrates for the performance. 

So it's been a bit of a roundabout answer to your question. But I think there are many things that are very important to consider in terms of like what is important and what is so fascinating about this topic? 

[00:49:35] LB: I think that was great. And what I love about that is very much the strong argument as to why we need to consider this. And I guess, again, particularly in athletes. Those that are aiming to achieve something significant with their performance and their physical outputs. 

But, Kirsty, what about if we choose to ignore these differences? What are the consequences that for you are real red flags that we really must take into account? 

[00:50:04] JA: I’m not sure if I understand the question. Would you be able to reword it? Sorry.

[00:50:09] LB: Yeah. I mean, I’m just simply saying that we're very much focused at understanding the differences or the specific needs of the female athlete. Because what we're looking to do is enhance adaptations to training into performance ultimately, whereby ignoring that fact may not result in those elite performances that we're looking to gain in our athletics. Because we're very outcome-focused in that. 

But what are the consequences, I’m aiming this at Kirsty more at this point, of not taking that into account? What are the risks?

[00:50:44] KES: Great question. And before I answer it, I’m going to give you a little bit of background to this special edition, because I think what I’m going to say will sort of add to the answer. So when Jose and I were considering who might we invite to write these papers. And of course, with a special edition, there are reviews, there are sort of little opinion pieces. There's sort of a temptation. Or maybe, historically, you sort of go for people who are well-known in the area. And a lot of benefits come with that. So if they're well-known, and they've published a lot, they've got experience, and they can speak with confidence of experience and a lot of sort of underpinning knowledge. 

But actually, that's great. And we did do that to some extent. We also wanted to sort of ferret out some people who maybe hadn't done a lot of research of female athletes, but who were quite prolific within sort of sports nutrition. And sort of to challenge them almost a little bit to say, "Well, you sort of really mostly research in men maybe on a particular supplement. What do you know about females? And why haven't you turned your attention to them?" 

And so it was almost like setting some research is a bit of homework. And they were great. All of our authors were fantastic. Jose and I were so pleased how willing they were to do this. And so, yeah, many of the groups went away and took their area, which did probably 99% only conducted in males themselves as researchers. And then started to try and find research in their field on females, and then unpick that. And that was really interesting. And that threw up some things, feedback from the authors, of, "Gosh. Why have I not been researching in women? And what are the difficulties? What are the challenges of using females?" 

And like you said, coming back to your question, what are the pitfalls if we continue just to do our research in supplements, or energy availability, or gut health in men? What are we going to miss out on? 

So I think the answer to your question is, in addition to those performance outcomes, it's health, isn't it? And particularly, if we take the example of low energy availability, and Jose already said this, it seems like women are more susceptible to the adverse health effects of low energy availability. So we think that the sort of depth and breadth of low energy availability – And this is where, in a podcast, it's awful for me, because I’m a very visual person. And my hands are flying around. 

But if we look at sort of, I’m going to say, the depth of low energy availability, it seems that women, it may take less time and a lesser extent of low energy availability to see a negative outcome. Whereas with some men, they can go sort of deeper into low energy availability and for longer before they see the same negative health consequences. 

I think the red flag is, if we continue to you know not really include women in this area of research, health will suffer. And it's not just about health as in we're going to break somebody. Because I think when we think historically of the female athletic triad, and bones, and a bone injury, that's sort of a consequence to me where you're broken. But I think health shouldn't just be broken, not broken. And it's a spectrum. 

I think, actually, if we focus and we include women in gut health, and supplementation deficiencies, and all aspects of nutrition, we'll have better health not just avoiding injury. We'll have better health. And we know that better health is better training. It is better performance in the long term. So I think we really allow – The whole goal here is to allow any female athlete to achieve her potential on any day, whether it's that day of her menstrual cycle, because she takes a hormonal contraceptive, because she's pregnant. It's about putting them in the best position to be at that optimal level. 

I think, for me, it's very related to health. But it's also as well – I guess, another small tangent. I promise, it won't be long. It was interesting, I think, when we looked at the women's football team, the American Women's Football Team. And they'd sort of started to think about – They were one of the first teams to publicly say. I’m not saying they were the first team to do it. But I think they were quite public about starting to consider menstrual cycles and hormones into their practice. 

And, for me, I don't think they did anything sort of in practice that was different than what anybody else was doing. What I think was the game changer is that the athletes themselves, the female players, felt valued. And I’m not going to call it a placebo effect. But it's that type of thing. 

For the first time, people, practitioners, were coming to them saying, "Tell me about your menstrual cycles." And before that, nobody was asking about that. And it was almost something to be embarrassed about. 

So I think, as well as these performance and health benefits, potential health benefits, I think it makes female athletes feel valued that nothing now is out of bounds. Nothing is off topic. If you're a practitioner and you're asking me how I slept, why should it be any different if you say, "How regular do you menstruate?" "Okay. You're not menstruating, and you should be? Oh, let's look at energy availability and so on." So I think that's a big part, well-being, feeling valued, and feeling equal to their sort of counterparts, sportsmen. I think that's a big thing for me.

[00:56:02] LB: No. I think – Yeah. And a point there is particularly in practice. It's good to talk. And a lot comes out of that. And I think, yeah, historically, it's been a bit frightening as a male practitioner to even delve into that conversation of, "How are your hormones today?" sort of thing. But that's where we're at now. 

Speaking of which, so in the paper on substrate metabolism during exercise, we're introduced to something, which I hadn't heard this phrase before, which was sexual dimorphism. And sexual dimorphism of energy metabolism. And in particular, the impact that this has on women's hormonal status, specifically on substrate utilization, is something that I think is particularly interesting. This was a particular paper I found of interest. 

Now, to divide this between the both of you, Kirsty, can you tell us what does that term even mean, sexual dimorphism, particularly in this context? And then Jose, we'll move on to you where you can tell us a bit about how that might impact actual substrate metabolism, for example.

[00:57:06] KES: Oh, finally. I’ve got a question that I can answer very briefly. But that sort of sexual dimorphism and that was sort of spoken about in that paper, and actually in other papers that that particular group of authors have written. They're really are experts in the topic 

It really just means that we're seeing different responses. So the opposite response in sort of males and females. So it's a dimorphism. There's a separation in terms of sort of sex response. And we use this term actually in things like cognitive function as well. So we see, it's really just a very nice and fancy way of saying they have different responses between sexes. It's sort of polarized. If it goes up in men, it goes down in women. If it goes up in women, it goes down in men. So that's what that means. And so a short answer, which is unheard of from me. So I’m glad you've asked me that bit. But I'll – 

[00:57:56] LB: Well, it's great, because it's an exemplar of why we need to be having this conversation, because we can't just assume that it's the same in every athlete, male or female. Isn't that right, Jose? I mean, what are your thoughts on this? You've you've spent a lot of time looking at athletes, and more than most on female athletes, as you've already said earlier. How is this relevant to this conversation that we're having today? 

[00:58:20] JA: Yeah. Well, I think in relation to what you were asking before and sort of substrate use, I think there's evidence to show that sort of females rely a little bit more on fat utilization during exercise than men. I mean, that it is a statistically significant difference. It doesn't mean that the magnitude is huge in terms of the difference. There is a difference, but the magnitude doesn't seem to be like massive.

When it comes to sort of skeletal muscle glycogen, that is super important as we mentioned before for performance. When you look at the data, sort of what's been published sort of cross-sectionally, it doesn't seem that really there is a huge difference in terms of the capacity of females to store skeletal muscle glycogen. But we need more data on that. And so I think, again, this goes – I might be like a bit of a broken record here. But I think we need more evidence to say what are the implications of this. 

I'm going back to your previous question. I think, just for me, like the beauty of physiology which makes this area so fascinating in terms of how things are different. But I think we still need to tie the differences that we see at a hormonal and physiological level to performance outcomes. And we need a lot more, as Kirsty would have highlighted his quality research, in terms of like looking at the differences in performance. 

[00:59:52] LB: When you read across these papers, we're learning, of course, about females in various capacities. But the effects of estrogen and progesterone fluctuations across the menstrual cycle and its impact on various things, including fluid and electrolyte balance. Again, another great paper there that I read as part of that. 

But again, one concludes that and goes, "Well, okay, there are impacts of these things. But how relevant is it to our day-to-day advice?" Kirsty, is it again a case of, "Look, we just don't have enough information on this? It is significant, but we don't know how significant yet." 

[01:00:31] KES: Yeah. I think that probably is it. It's been mindful. I think you could argue, "Why do I need to read this special edition?" Is everybody just going to conclude we don't have enough evidence? And so therefore, all bets are off. We know nothing. That isn't the case

I think the way that we wanted the papers to read and enhance sort of the title of what we know, what we don't know, and why, is that each of those papers, although they discuss the limited available literature, although many of them or all of them conclude we're not there yet, they get you thinking about why that might be a consideration or why there might be a difference in females or even in different types of females. And I think that's what you bring into practice. 

So you might not have the answer, as in, if you drink this volume, or if you eat this, or you time your carbohydrate here or whatever. We don't have those answers. But what we do have is an open mind. Actually, do I need to do something different for you? And what might that be? So it will take a little bit of sort of practitioner investigation. 

But if you close your mind off to that and you just think, "I’m taking the published literature from data derived from men. And I’m going to make a fit for women," then I think you're missing a trick.

So, yeah, we are still in that sort of, as I say, that space, where we're not going to stand still. We're not going to wait for high-quality evidence. We are going to move forward. And moving forward for me is going with an open mind. 

I said about asking about lived experiences, which I think absolutely. So keep that. That's point one. But point two is, as a practitioner, having an open mind to, "I read that paper. It explains to me why there might be a sex difference. And so therefore, although they haven't told me what to do, if there is one, I’m going there open-minded. I’m looking for that. I’m mindful of that potential. and I’m going to then address that if that's what I encounter." And so I think they would be the two things. Sort of asking about lived experiences and being an open-minded practitioner, opening your mind to potential sex differences or within sort of women and differences. 

I feel like I’m not articulating that well. I think I need some new language around these within women difficulties. But yeah, I’ll have to develop some new terms. But hopefully you get what I mean.

[01:02:41] LB: I do. But that's what makes this so interesting, is because there is an issue there, isn't there? There is a concern. There is a need to address this. And that's why we need more research. We need more evidence. And we don't just need any research. We need more quality research. Because it's clearly difficult to wade our way through all of this evidence that exists out there and actually determine how much of it actually is relevant. And some of it seems to be knocking on the door of probably the right doors. And some of it is a bit misleading maybe. And partly, is that because some of maybe the lower quality research is just easier to do? Is that part of the issue there? Is that what's going on? 

[01:03:21] KES: Yeah. I mean, for sure. The sort of what I’m going to sort of say, the lower quality studies. And again, I said there's a huge – A big influx, a large increase in the volume of papers. And actually, the speed they're coming, it worries me, because to do a well-conducted, high-quality study takes time. And they're just coming so quickly. I already almost know before I’ve read them that there are probably going to be methodological sort of shortcuts. 

So yeah, you're right high-quality studies, they take time. They they take money. That's the other thing. Because of the sort of repeated measures aspect, the multiple time points, the outcomes, usually to be high-quality, you need the hormones measured in blood. So it's costly. It's time consuming. 

And, please, I think, in the past, I may have badly articulated this. So if you'd give me two or three sentences to set the record straight, what I will say is I think there are a lot of well-intentioned researchers out there. And maybe I haven't given them enough credit in the past. People aren't, researchers aren't setting out with the intention to flood the market with low-quality research. They're well-intentioned. They want to help. 

And hats off to anybody who's going to change their focus, learn about the underlying endocrinology, physiology associated with women and try and implement that in the study. Absolute credit to anyone doing that. And as I say, they're well-intentioned. 

But it's about slowing down. And it's about taking our time. And I’d rather see fewer high-quality studies come out. And I’d even like to read on social media about people who are going, "I’m doing this study. Give me a year." And it's like, "Cool." That, to me, gives me more confidence. It settles my nerves more than the papers that are popping out every week that were conducted in three weeks' time frame and just have cut some corners. 

So as I say, whilst I am critical of the quality of some studies, I’m not critical of the researchers. I do give them credit. And I do understand how difficult it is. But I would say, let's slow down. Let's try and maybe come together as researchers. If we work together, we'll get bigger N numbers, better powered studies. We can pool our resources. But yeah, let's focus on increasing the quality of the studies. 

Because, actually, I don't know. I’m 20 something years into this area. And now I know how to rate the quality of studies in this area. It must be a minefield for people new to the area, or practitioners, how do you ascertain yourself whether or not the quality is good and whether or not you should be confident in those findings and change your practice? And I think that's really difficult. 

But I guess the last bit to the story is, because there's such an appetite for this, because we're all so well-intentioned, because we're rushing to bridge this research and knowledge gap, social media, and actually just media, the media in general, are picking up on these papers and big punchy headlines, "Do this and you'll fix everything in female sports." And that's also causing problems.

So, yeah, I don't know how you know the sort of media and how sort of people who are maybe a little new to the area, how they're navigating this. But yeah, it can be difficult. And certainly, you don't make friends in the scientific community by criticizing people's quality. But we do. We've all got to get on board. High-quality confidence in the finding. Let's do the best for female athletes. 

[01:06:41] LB: Yeah. Look, I said right at the beginning of this podcast, my thing here is largely about how do we look at all this information, or read, interpret, and move things around so that we can determine the relevance of that as it relates to the advice and recommendations we're aiming to give very specific people in very specific situations. And like the late Prof. Tipton would always say, is, "You need to be skeptical and open-minded." And that's not an easy thing to do, because in order to be skeptical, you need a little bit of knowledge and training, or a lot actually. And to be open-minded, you need to know where the limits of your open-mindedness needs to be. It all gets rather complicated. But it is only by us having these conversations where there are very static limits to information that's printed into a paper or a textbook chapter. 

What I aim to do with these podcasts, for example, is bring it to life a bit more and for us to talk about these things. And we've looked at different things from different angles. And there's no – I think we all agree that there isn't necessarily a right or wrong. It's just we need more information for a start. And we need to differentiate the quality. 

We've only scratched the surface, clearly, which is sort of a conclusion we have on almost every single podcast I’ve done, even on topics that people believe are to be very firmly entrenched. Like the quality of protein, like it's got to be animal or dairy-based. Not necessarily. I think all of that is what makes this so fascinating. 

But look, I mean, we've been talking for well over an hour now. And we should draw this to a conclusion soon. And I want people to read the special editions that well-worth spending the time to get into. But there's a couple of little topics I think the listeners will want us to get into, particularly the consumers. There are some people that listen to this podcast who are athletes and/or early stage researchers, undergraduate students and so on who haven't necessarily gotten to this point of understanding this information. 

I mean, Jose, there is one area that you're at the forefront of, which we've briefly touched on, which is this idea of relative energy deficiency. You've both done tons of work on this. We've done podcasts on this. But even after – What is it? 30 years now or something? That we sort of associate low energy availability. There's eating disorders. There's menstrual dysfunctions. There's impaired bone health in athletes and so on. Where are we with this level of knowledge, Jose? And is it as relevant as it was five years ago? Is it becoming more important? Do you feel it's going down sort of a pathway of distraction on this topic? Where do you feel we're at with this? 

[01:09:26] JA: I must highlight that there's no conflict of interest in my answers. But I must say that I think it's still very relevant. No. Yeah. I think it's very topical. People are very interested in the topic. I think it's a very relevant as ever, really. I really, really like this area of research. And I’m putting pretty much all of my energy into developing this area of energy, of energy availability at the moment on our understanding. 

When it comes to sort of female-specific – So implications that are specific for females, I think this is like super, super relevant. We're still having a lot to understand of like how the knowledge that we have from laboratory-based studies translate of what happens on the field. 

And my understanding, my experience, there's a lot of misunderstanding in the sort of stakeholders, coaches, athletes in terms of what's happening. A lot of like black and white thinking. A lot of, still, not understanding of what represents to have or not have sort of the regular menses and so on, and the implications of low energy availability for performance and health, which these are interrelated, but it's not necessarily that low energy availability automatically would result in impaired performance. But it can impair performance. This is something that we still need to do a lot of research about. 

In terms of the importance, in general, of all this research, not only in low energy availability, but in general, in like female athletes. I think I’m going a little bit of – Not off topic, but talking a little bit outside of strictly the science of it, but in terms of how we apply this science, it's like normalizing the conversation with athletes and coaches and all the people that are sort of on the ground working face-to-face with athletes. 

And something that came to my mind when Kirsty mentioned about the conversations that she has with the athletes that I think are super relevant. But she's very comfortable talking about this with the athletes. And what I see – And I’m very comfortable myself talking about this thing with female athletes. But something that I see, for example, is a lot of coaches are male coaches, and they fear talking about the menstrual cycle, for example. This is like this thing that is taboo. And I think it's a lot about the work that we have to do, is like do more quality research in female athletes, and nutrition for female athletes, and sort of make this taboo disappear. 

Because, again, I think there's beauty in physiology in general. Particularly, the menstrual cycle is sort of masterpiece of nature in terms of like what it represents physiologically. And I think it should be seen as not something that is in the middle, but it's something beautiful to be understood, to be embraced, and to really be worried off when there's lack of that. 

This reminds me a little bit of Conan Doyle's Basker – The Hound of the Baskervilles. 

[01:12:32] LB: The Hound of the Baskervilles. Yeah. 

[01:12:34] JA: Yeah. The signal is when the dog is not barking is the same with the female athlete and the menstrual cycle. And this is something that I think we should make a lot more people aware of. And the likes of Kirsty and a lot of other good researchers out there are doing amazing work in sort of highlighting these things.

[01:12:53] LB: That's brilliant. I mean, look, guys. There has to be a limit to where we take this conversation. And I’m aware of so many gaps. I will signpost to the numerous podcasts that I’ve done with you guys and some other of my great guests that have come on, which will tackle some of these topics in more detail. And I’ve also hoping to get a number of the authors of some of these papers to get into some of these topics in more detail. So we're certainly not done on this topic.

But there is a quick topic I wanted to finish up with, which particularly on social media or whatever seems to always be a popular one, of course. And that is the topic of supplementation. It's always pushed for various reasons. And it may or may not be relevant to human performance. 

But as far as females are concerned, Kirsty, where are we at in terms of evidence, and supplementation, and nutrition for female athletes? 

[01:13:47] KES: What a question. 

[01:13:49] LB: I end with the best bits.

[01:13:51] KES: I’m going to quote you back to you. Well, I love the way. You always say, "Test. Don't guest." And I think that holds true, doesn't it, for athletes in general. Of course, if somebody is deficient, and that warrants us supplementation, then absolutely. So I would go with that as a guiding principle. 

I mean, of course, not all supplementation is for deficiency. Well, I’m thinking more sort of clinical deficiency. But for wonderful words. I guess, the more sort of general sports supplementation and sort of swapping that may be a food group for a supplement. Yeah, the short answer is we're not there yet. 

I think one of the papers is on sort of sodium bicarb, for example. And there's just such a lack of evidence. Again, even the studies that are out there are sort of hindered by maybe the groups weren't homogeneous and so on, and so on, and so on so. I said I was going to give a short answer, and I didn't. 

So I would say test, don't guest, for the more sort of clinical deficiencies. Quoting you back to yourself. And then for the other ones – There's probably a good name for that that I can't think of at the minute. But for the other sort of sports type supplementation, I would say we're not there yet. I would still take that more guided by the sport approach. 

Who was it? Oh, I always like to give people credit for their sayings when I steal them. But I can't remember who it was. But they said that in the supplementation sort of industry, there's a shrinking and pinking attitude. So that they take the same supplement and they stick it in a pink jar for women, for female athletes. And that makes it more appealing. 

So yeah, let's definitely avoid the shrinking and pinking attitude. And yeah, let's be sort of more pragmatic. And actually, there's that paper recently. Oh, God. I’m probably pushing people and papers all together into a big mess. But I think you could probably help me. Didn't Graham Close recently put a paper? Because their saying is – Isn't it? Food first. But not always. And that I really like that. 

And so I think, yeah, there are better people to answer this question to me. But maybe you can pick out a few sort of things from what I’ve said there in that jumbled mess. 

[01:15:53] LB: Well, so, food first, but not only is the podcast – We did that a few podcasts ago. So there you go. See? That's the thing that comes together. I don't say it so often now, but I had for many years, my obsession on the idea of context and why it's relevant. And it is an entire chapter in my doctoral thesis about why context matters. 

[01:16:16] KES: I’ve stolen that from you in many presentations. 

[01:16:19] LB: I know. I’ve even seen people. Like, Graham Close would do lectures. And you talk about content. A little picture of me on the top right-hand corner. I mean it's not like I invented the idea. But it is important. And I guess that's the ability to contextualize to make it all relevant is what we're after, particularly if you're in the business of advising elite athletes. You're in the business of giving people advice and recommendations where they're hoping to achieve benefits from that. It does matter this stuff. And I guess, yes, there's the do no harm aspect. But that's not so easy. 

Like, Jose was just talking about with relative energy deficiency. And you've obviously talked about it. And its impact on things like bone health and various other things. There is an implication to people's health, not just their performance, but to their health if we don't get this stuff wrong. 

But all in all, it's been a fascinating conversation with you guys. It's by no means the end of the conversation. I will, like I say, get people to read these various papers. I want them to listen to the podcast. And we'll definitely have you guys back on in the near future. But at this point, I think we'll bring this to a close. 

So, Kirsty, thank you so much for all of your knowledge, and enthusiasm, and expertise, and holding as many punches back as I know you felt that you needed to. And Jose, saying all that immense knowledge and experience. And thank you both for spearheading what is a really important collection of papers in this special edition. So, thank you very much. 

[01:17:49] JA: Thank you, Laurent. 

[01:17:51] LB: Okay, guys. Well, thank you for that. I’m going to say goodbye. Take care, everyone. And it's been a pleasure bringing another episode of We Do Science to you.

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