Nov. 3, 2022

"Physiological and Nutritional Considerations for Training & Body Composition in Females" with Professor Abbie Smith-Ryan

Episode 180 of the Institute of Performance Nutrition's "We Do Science" podcast! In this episode, I (Laurent Bannock) discuss "Physiological & Nutritional Considerations for Training and Body Composition in Females" with Professor Abbie Smith-Ryan (University of North Carolina, USA).

Discussion Topics Include:

  • Gender as an important contextual consideration in training and nutrition recommendations for exercising females
  • Research on females relevant to sport and exercise science and nutrition
  • Issues with body composition assessment and manipulation in females
  • The effects of nutrient timing on training adaptations in resistance-trained females
  • The acute effect of exercise modality and nutrition manipulations on post-exercise resting energy expenditure and respiratory exchange ratio in women

Podcast Episode Transcript: Download PDF Copy

Key Paper(s) Discussed / Referred to:

Related Podcast Episodes:

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[00:00:01] LB: Hi, and welcome to episode 180 of The Institute of Performance Nutrition's We Do Science podcast. I am Laurent Bannock, the host. Earlier today, my discussion was with Professor Abbie Smith-Ryan. Abbie has been on the podcast a number of times to talk about a number of different topics. And if you're familiar with Abbie's work, you'll know that she's a real tour de force in the sort of applied physiology area, particularly as it relates to female strength conditioning performance, particularly nutrition. It's been a fascinating conversation that we had today where we sort of dig in a bit organically, but the conversation revolved around this topic of female athletes. What does that mean? But particularly, when it comes to things performance, body composition, there are a number of considerations that one needs to factor in. And I think that you'll get a lot out of this conversation as I did.


When you think about females, age, of course, is relevant. When you start to think about menstruation, perimenopause, menopause, the differences that exist as a result of not just that, but just general female physiological differences between men and women in the context of strength, performance, power, and endurance, and, of course, body composition. 


Anyway, that's just a little teaser. I think you'll get a lot out of it. But before you get into today's discussion with Professor Abbie Smith-Ryan, just quickly check out our website at where you can learn about our new level seven diploma in sports nutrition. Level 7 being master's level program. Very excited. It's the latest version of our program, the diploma of The Institute of Performance Nutrition. Practice focus. All about applying science into practice. You can learn about that at our website. 


You can catch up with our past episodes of the We Do Science podcast, and this episode today, where I'll have links to the various papers that we've referred to. Whilst you're there, check out also our SENPRO software platform, which is all about supporting practitioners working with individual clients, team settings, online coaching, you name it. If you're a performance nutritionist or a nutrition coach working with active people, then SENPRO will provide you with a range of tools and resources that will enable you to get the most out of your coaching process with your clients. 


Anyway, that is all I wanted to say. Hopefully you'll enjoy this conversation with Professor Abbie Smith-Ryan as much as I did. Enjoy. 




[00:02:57] LB: Hi, and welcome back to the Institute of Performance Nutrition's We Do Science podcasts. Today, I am really excited to be talking to someone. I've known you a little while. And by a little while, we've met a number of conferences. You actually came as a speaker to a conference I organized. And I got a feeling so old when I say this, but that was like nearly 10 years ago in itself. I mean, eight to ten years ago. I can't quite remember quite how long ago. It might only be seven years ago. But it doesn't matter. It's been a long time. 


And there's been a number of changes in the world of course, but I think one of the most exciting ones is the one I've just learned, and that is that you are now Professor Abbie Smith-Ryan. Welcome.


[00:03:38] ASR: Well, thank you for having me. And, yes, it's been too many years. I'm really happy to be able to sit here and chat with you today.


[00:03:44] LB: I'm so grateful. I've heard you speak many times over the years. And I've followed your work ever since I first met you at an ISSN conference long time ago. And you've been involved in areas related to sport and exercise nutrition, health, fitness, performance, body composition and so on. And I know you're a really dedicated researcher. You just have to look up your publication history and you can see just how much work that you've put out there in great journals and so on. 


But as with most researchers, there will be variations in your interests over the years. But you seem fairly firmly focused on a number of areas I'll let you discuss with us in a minute. But I'm really excited to talk to you today, Abbie. Bring us up to date then. What have you been up to over the years? And where are you now with your work? 


[00:04:36] ASR: It's funny, I was thinking the last time I chatted with you on this podcast was with Dr. Craig Sale about beta alanine, which is where my kind of career started. And I still do some dietary supplement work, but really focus a lot on the metabolism, body composition and with a focus in female health. And I think back actually when I came to Middlesex to speak, it was on nutrition for women. And that was seven, eight years ago. And so, it's still within that theme. And I'm still very passionate about that. 


But the most exciting part and why I like to specifically come talk to you is no one reads the papers we write. It's about the translation. And so, I'm excited to just talk about like what does this mean? How do you apply it? How does all the science – Most of my science is rooted in the translation. What does it mean? And how do we change an informed practice? 


[00:05:27] LB: And that's perfect, Abbie, because that is what this podcast is all about. And there's a lot in what you've just said that will ring true for a lot of the people that are listening, particularly those that have listened over the years. I've got a number of things I get really obsessed with, things like the context or relevance of these things that we talk about. But also, how we need to be mindful that a lot of the research is either maybe not so great in terms of quality. There's a lot of quantity as it relates. And there's lots of reasons for that. And there's a million and one different journals. And there are all sorts of you know pressures on people to publish and so on and so forth. 


But actually, the greatest problem is not so much the abundance of those publications. I think it's as you have just said, it's the issues that relates to their translation. And that's what we're interested in on this podcast, is to discuss these things but make sure that we unpack the evidence into the appropriate context so that everyone's can – I guess what they need from this. 


And yeah, it's true. Not everyone read these papers. Although, I'm going to link to the ones that we'll talk to about today. Maybe we can change that metric slightly, Abbie. But just give us an idea about over the past few years you've been publishing a certain amount of research on certain topics, that sort of thing. Just give us a little bit of background as to why you got into this area in the first place in your early career. And I realized that's pushing it scratch your head there, Abbie, and have a think. But why did you even get into this whole field? You could have done something else. You could have been an athlete perhaps.


[00:07:11] ASR: Yeah, that's a good question. I mean, I think my reason is the same now that it was, I don't know, 15 so years ago. And my goal is really to improve health and quality of life of the individuals around us and do that with a feasible and effective exercise and nutrition approaches.


And so, most of my work involves – I wouldn't want to say the shortest amount of time and the most supplements. But how do we really take approaches to exercise and nutrition that people can actually do in their real life? And that is not normal everyday people, clinical populations, as well as athletes. And looking at how can we make things small tweaks to maximize what we're doing with our workouts and nutrition? 


And so, I do a lot of intervention-based work with exercise and nutrition and dietary supplements. But then a whole other arm that I think is very valuable that I've spent a lot of my career on is body composition measurement. And so, what is the most valid method? What's going to be the most sensitive? How about limb asymmetries? And how is that impacted by food, and sex, and a male female? Those types of things. So that when we – And a lot of that I do with elite athletes because their bodies are so different. And what's the impact of race and age? So that we understand how actually things are changing when we're creating interventions. 


I really want people to enjoy exercising to feel the benefits and not have to exercise all day every day and eat only the foods that – whatever. The healthy foods. It's really how do we maximize our life and feel better? 


[00:08:49] ASR: If we just go back to something you mentioned, which was the very topic of that presentation you did for us seven-ish years ago, about nutrition for female athletes or active females. Now, if we just bear in mind that even right now, although this is suddenly. I used the word, carefully, suddenly because it's obviously not a sudden process. However, it's still a minority of researchers – Research generally is focused on female. And there's some reasons for that. And we've discussed that in some previous podcasts. 


But I mean, we go back seven years. I mean, you were literally in the wild west at this point when it came to that particular topic. I mean, I'm just interested to know that not necessarily why take the path of least resistance and just do what everyone else is doing, but why did you feel that that was an area you wanted to specialize in? 


[00:09:42] ASR: I think for so many reasons. And it wasn't because I was a woman. I think it was I had spent enough time in the field to have a good understanding of how the human body was responding when you layer on a stimulus like exercise. Spent enough time looking at specific dietary supplements to really start asking like, "They don't line up." The physiological response and what we're studying, they could be different in women. 


And then I think this is maybe where some of my personal bias comes in. But the transition of a woman over a lifespan is incredible. Even when you take from when they hit puberty and then you add in physical activity or elite athletes, and then you add in pregnancy, and perimenopause, that transition to age. There's just so many things there where a lot of women are struggling or there's just not a lot of conversation about what's happening. 


And then when we look at life, things like caring for a family, a full-time job, trying to reach you know specific exercise goals, there's a lot of things that can help make it easier when you layer that in. And I have had some really fortunate interactions with different companies and product development and that kind of translation and nobody was having that conversation. And I think it's not acceptable. And so, if I can contribute to that, that's one of the benefits. 


I laugh when you say I'm a professor. Well, the only thing it really allows me to do is to do what I want to do and worry less about. I still have to you know check the boxes. But I can push through some of that resistance. And the goal right now with some of the female stuff is to make it easier not only to study, but also to interpret and to understand. And we're doing a lot of that now so that it is easier to study women and to integrate some of that into more of our research and other labs as well.


[00:11:33] LB: That's awesome. And I'm really grateful that you're doing this. But I'm going to ask you a question, which, I mean, especially seven years ago would not have been obvious at all. And some people might think this is an obvious question. But why is it important to differentiate males and females if we potentially have more in common than we don't depending on how you look at that statement? But is it not – it obviously requires attention. But why, Abbie? Why do you feel it's needing so much more attention than it currently has for you to focus so much of your time on this? 


[00:12:08] ASR: Well, yeah. I mean, I think we actually have some really great data to suggest that there aren't a lot of differences when you compare males and females for certain exercise outcomes. But what we're missing is how the woman responds. Even throughout you know a monthly cycle, a woman is going to differ in how she responds compared to a male. And then you throw in contraception. And then just this so many changes over our lifespan. 


And I chuckled last time I was with you. I had had like a six-month-old. I was postpartum. And just the lack of data and the changes in physiology that can really be targeted with certain exercise and nutrition approaches. And it's just the majority of the world is female. And when the majority of the data is based on males – I think one big stride is that I don't think we need to necessarily make sex-based comparisons. How are males and females responding differently? But let's ask a different question? How are women responding when we are prescribing the same exercise or these basic nutrition or key stuff elements that have been studied? Maybe the dose and things do not need to be different. But we don't know that right now. We do. We're getting more data. But I think we have to recognize that the longevity of women and the majority is there and those things need to be met especially as we transition through life. And we see some changes in health discrepancies and some of those things.


[00:13:28] LB: Yeah. No. Well, I mean, the evidence seems to be very much going in this way. And I think for me, there's one extra thing you could add into this that really skews it towards females in terms of us needing to understand much more about this is when you start to look at the age of a female relative to men. To a certain extent, during the lifespan of a male, the differences from sort of young adulthood to a guy in his 50s or 60s maybe not such a big difference unless we're talking about certain elite areas. But for females, it's massive, isn't it? 


Let's just get into that. In terms of defining – And again, this is sort of an obvious question, but it isn't. From your perspective, how do you define a female or a female athlete, of course? And what are the sort of things that you have to do in your research to be able to make those – differentiate those different metrics if you like?


[00:14:31] ASR: Oh, yeah. I mean, you've had some great speakers. And [inaudible 00:14:34] doing a lot of this work. What we're trying to do is clarify that a little bit more. And how do you study these women? Understanding do they have a normal menstrual cycle? What type of contraception, if any, are they using? And then a lot of my work is looking at women once they've started perimenopause. So, intermittent menstrual cycles prior to hitting post-menopause, which is a single point in time. 


And the reason partly why I'm so passionate about that is a lot of women don't know that they're in perimenopause. And that's when a lot of physiological changes happen both mentally and physically. The other kind of interesting thing is, in the U.S., the Title IX laws, like when women in sport just kind of propelled them. And so, now we have all these women from Title IX that participated in sport and are either perimenopause or going into post-menopause. Kind of going from this very highly active life. And what's the impact? We don't know you know. 


When we tied it in to metabolism, there's a lot of things that change with the mitochondria that impact metabolic rate and Metabolism that can result in weight gain and fat utilization differences. And so, really, there's a lot that can happen that we just don't understand especially if you layer in the people that were active. 


And I'm thinking the World Cup and women's soccer, football, as you all call it, there's so many women now that have had children and then returned to sport. And that's just not been studied. How do we maximize that and maximize their body so that they can perform whatever you want to define performance as? 


[00:16:08] LB: No doubt. This is a treasure trove of areas to go into. I come at this from the perspective of being a practitioner. And I'm sitting there. I work with many more males than I have females on. I'm absolutely no expert when it comes to helping and supporting females. 


But it strikes me that there's so much you need to do to understand the needs and preferences of your athletes. A lot of things, as a nutritionist, you're confronted with is just basic things. Just basic needs and preferences. What do you like? What don't you like? What's actually practical? 


And yes, of course, we get very much into things like energy balance, energy availability. Big area that I find particularly with the elite athletes, particularly endurance athletes, or team sport female athletes, can be relative energy deficiency and all the hidden problems that occur. We've definitely done podcasts on that with numerous researchers. But doubling back on myself as a practitioner who, for the sake of this conversation, is not a researcher in that context. Doesn't have access to all the kit and the equipment that you have. And indeed, the cohorts of women that are volunteering for your studies. You're sitting there trying to understand what's going on. 


From your perspective as a researcher trying to help support the practice, the application of this, what are the areas that you feel have been missing in the data so far that you are or want to be focusing on that you feel will help us move forward in that sort of area? 


[00:17:45] ASR: Ah, gosh. That's a loaded question. I mean, I think right now there's a lot of conversation of how negative is the menstrual cycle on things like performance, and sleep, and nutrition? And even how does the oral contraception impact chronic adaptations to exercise? And I think we don't know. Every person is different. 


And so, I think, as a researcher, that's a little bit challenging. But what we're trying to do is study different types of oral contraception and normal eumenorrheic equipment of how is physiology changing across the menstrual cycle or throughout a pack of birth control pills so that we can understand and how we might – Not treat it. But overcome some of those barriers if they are being had. 


And so, I think I would take a step back. And when we think about the practitioner, one thing that we haven't done a good job – I was a former Collegiate athlete. And we never talked about menstrual cycle or periods. And even when I talked to – And we interact with our collegiate female athletes here at a very D1 institution. Or as women, as they are in perimenopause, kind of that 42 to 52. Many of them have never even considered when their period happens? And what happens around it. 


And so, a lot of times, to me, it's asking, "Are you having a period?" How long do they last? And really having the conversation of the individual to recognize what are changes that are happening? Do you see changes in your sleep? In your mood? in your nutrition? In your fatigue? Because those are the things that matter more than whatever we're collecting in the lab. But the hope is that we can take research to inform some of those questions because it will be dependent upon the individual. 


Or, for example, there're thousands of types of different birth controls that you can take. We can't study all of them. But if you can have an individual recognize, "Oh, yeah. I do feel that. When I take my placebo pill, I do feel a certain way." "Okay. Well, maybe another type of birth control you could try based on the side effects." And so, I think it's really giving ownership back to the women for them to realize these are the things that you could feel. It doesn't mean you are going to feel these things. But let's recognize that if you do, there's things that can over come. I'm being quite vague. 


But for example, we know that through some phases of the menstrual cycle you might have greater soreness. And so, if you're more sore, well, there's easy nutrient timing ways to reduce soreness, or think about maximizing sleep, or modifying training load if someone is feeling those things. And so, I think it's taking the individual approach based on high-level data that can inform that practice.


[00:20:29] LB: That's great. That's what I was expecting to hear and what I was hoping to hear, I guess. If we can accept that there still isn't that much research out there, there's not a whole lot of evidence. You've mentioned that in some of your papers over the years. And of course, you're working hard to help fill some of those gaps or some of your colleagues around the world in this topic. 


If we try and understand on the body of knowledge that does exist as it relates to females, I made a comment about, in some ways, we have more in common – As in we as in men. Have more in common with females that you may apply to general concepts like energy balance, for example. And particularly, in non-elite athletes. And then obviously, there are elite athletes in different types of sports. And we can all get crazy with these conversations. 


But perhaps you could narrow this down a little bit to some of the areas that do appear to be more relevant in terms of female-centric strategies that perhaps are different than we might consider for men. What are the sort of areas that the evidence seems to be pointing out and you yourself have found in your own work?


[00:21:40] ASR: Yeah. I think a couple of things. This is not the paper I sent you. But one thing that comes to mind is we recently finished a couple studies looking at creatine supplementation across the menstrual cycle. And so, one thing that we see without any sort of supplement intervention is that, across a normal menstrual cycle, there is changes in fluid distribution. A lot of times women gain weight, water weight, and hold it extracellularly. They feel a little puffy. Feel a little soft, I would describe it. 


And so, two things. We've picked up on that with body composition measurements. And we know if you're using any sort of water measure – So we'll use like a multi-compartment model. Or if you're using some sort of bioelectrical impedance. That will be sensitive to those fluid changes. Meaning you'd want to account for the time of the month that you're measuring body composition because that will alter your results. 


If you're using something like a DEXA, it's less sensitive. And so, that's a good thing to know, the stability. But then when we add in something like creatine, creatine is obviously very widely studied in men. The work is growing in women. But when we look at the differences in brain creatine stores and some of the impact on recovery and phosphocreatine, just differences in fiber type, across a menstrual cycle, we're seeing that creatine can actually help with some of that fluid distribution in the high hormone phase and bring some of that fluid into the cell. 


And so, I think we see two things that could help with preventing some dehydration. And it could help also with some of the feeling of kind of edema, kind of bloating, because we're actually able to retain some of it. And so, I think now the question is how does it impact performance? That would be the next step over more of a long term. Kind of an application would be it may be helpful to do a creatine loading phase right before the luteal phase to help with some of that fluid distribution, which would also help with recovery and performance. And for men, obviously, we wouldn't see those implications. 


[00:23:41] LB: That's really interesting. I've read about this. I'm not sure specifically which paper you're referring to. But it's quite possibly a paper I've read. But this concept does get interesting again from the practitioner's perspective because you're talking to somebody who they're not just an athlete, they're not just female or male. But they're not just female. They're a human being. And they suffer sometimes from the impact that information can have such as gaining weight, losing weight, and the induction of feelings and emotional responses to that sort of thing, which of course can then have an impact on psychological state. Definitely from a nutritionist perspective, is eating behaviors and choices can certainly be impacted. And I guess from the sports psychologist perspective, there could be a whole mindset issue that particularly if this happened proximal to an event, they weigh themselves and they appear to be gaining weight. And they need to be losing weight if they're a weight category athlete and so on. 


It's not a new area. But it is a really interesting one how we measure these things. And you've already mentioned the difference between different compartment models, of course, and how we measure those from DEXA to skin folds and so on. But of course, we also get massive variations in the accuracy of that stuff. We're not yet starship enterprise type, Star Treky type phases of technology. But we do have some reasonably decent bits of kit out there. Between the lab and the field, what are your thoughts about those testing methodologies as it relates to providing that feedback to the athlete? 


[00:25:20] ASR: Like whether we should do it? 


[00:25:23] LB: Yeah. Or maybe we're doing it because we need to understand where they're at. But we don't necessarily need to feed that information back to them as royally as we might. Yeah, you know where I'm going.


[00:25:34] ASR: Yeah, yeah. Okay. Yeah, we do a lot of body composition measurement in our elite athletes. And there is always this fear, and especially in the U.S., of how messaging is delivered to the athlete. 


And obviously, you don't want to – Weight conscious sports, there's reasons not to display that. But a lot of the conversation and the view should be on muscle mass and lean body mass. And I know we have some papers and so do a few other labs. But looking at what we call fat-free mass index, which is the amount of muscle a skeleton can withhold. 


And we've created some sport-specific. We're the first lab to look at female-specific. And then there's some male-specific. But it really allows us to also understand injury prevention. 


For example, if someone is carrying lower skeletal mass or muscle mass, like you would anticipate, for example, on an endurance athlete to have lower muscle compared to let's say a weight lifter. But there are still normative data if you want that. If they're too low, then that gives you some insight that they may be at risk of injury. Some of those index. 


Another one is body composition index. Kind of looking at some changes. Kind of a loss of fat and gain of muscle and that kind of equivalent over time can give you an idea of how the body is changing particularly with the program. 


One thing that we've started to do too is look at custom regions of interests particularly for muscle, to go in and look at the glute, the quad and the calf with something like a DEXA. Or if you take something a little bit less sophisticated like a segmental bioelectrical impedance analysis, a lot of those are more widespread now. But looking at right side and left side for muscle mass that really helps you identify and can predict low energy availability. 


If you put them through a pretty progressive resistance training program and they're knocking gaining muscle, well, that shows us that they're probably not eating adequately. And then those values are also really important to calculate energy availability. 


And so, using those things, I would say, are very helpful for injury prevention, injury tracking, as well as understanding program design. 


[00:27:39] LB: There's so much to this. I'm thinking very much of another issue, which is the concern – Well, maybe the more recreational sort of gym goer level, there is a concern about, "Oh, if I'm going to lift weights or consume protein, am I going to get bulky? Am I going to get too many muscles?" And obviously, I remember talking to Stu Phillips about this. And he started going off on a tangent about testosterone and various other things. And almost certainly not really an issue with females. 


However, it is very interesting in the context of an athlete though, because they do want to benefit from training adaptations. They do want to get faster, or potentially stronger, or whatever. If we view it through the lens of the needs of an athlete, and of course, there are strength, speed, power athletes, there are endurance athletes. I'm guessing your answer might vary slightly depending on what type of athlete we're talking about. 


But we know a lot about how men respond to training and how nutrition, for example, can influence those adaptations. But as it relates to women, do we just do the same thing as we do with males? Or what are your thoughts on that particularly with athletes? 


[00:28:51] ASR: Yeah, I like your leading question. There is a paper that just came out that says if you train in certain phases of the menstrual cycle, it'll impact hypertrophy. But who trains in only one phase of their menstrual cycle, right? I don't think that's very practical. 


We've looked at, yeah, how does nutrient timing? The field of nutrient timing has been around for decades. And until recently, all of the data was done in men. And when you look at one of the key differences between males and females relates to metabolism. What fuel we are using particularly at rest and during exercise?


And so, that's one thing that we've looked at in my lab is, okay, there's a lot of good data on what to eat after exercise and sometimes before. But what we're seeing based on some of those metabolic differences is that eating prior to exercise, which is often a window that women avoid because we have higher gastrointestinal issues, and a lot of women are exercising to burn calories. And then when you do reach for something that's often very much a carbohydrate-based, which impacts then our ability to utilize fat, which is what we are more designed to do. 


And so, we've looked at some pre-nutrient timing versus post-nutrient timing in women specifically. And obviously, more data is always needed. But I think one takeaway I have is, as a female, regardless if your goal is endurance performance, or strength performance, or hypertrophy, having nutrients prior to exercise is probably more advantageous for you than it is for a male. 


And having some amino acids prior to exercise can be helpful in both of those scenarios. And so, that also goes against of what most of the information that we're hearing, intermittent fasting, or, of course, eat after. I really focus and tell women to eat prior to. 


Obviously, if you had a meal a couple hours prior to, you don't need to have another thing right before. But oftentimes, women have those long periods of time in between meals and then go to their exercise fasted with this goal of burning fat. When we see the exact opposite, is that having some protein prior to exercise actually enhances fat oxidation. Obviously, depending on the type of exercise. If it's high intensity, that's still carbohydrate use. But after. And it can impact strength and lean body mass gains by having enough fuel available. It impacts resistance training outcomes as well.


[00:31:18] LB: I love the topic of nutrient timing. Because if you hang around sort of the recreational gym type environment, there's a lot of arguments about whether or not nutrient timing is even relevant. There's the whole bond or conversation. Strategies for sports nutrition really aren't that relevant to recreational gym users. 


And what you've just talked about, the eating before or after. And of course, when you actually look at how long it takes to digest, absorb and the availability of a lot of those nutrients is around for some time. And actually, I can see the very logical argument for consuming before and not necessarily after. But it is the sort of acute and sort of medium-term response to substrate utilization that I think gets rather interesting, doesn't it? Particularly in the context of a female. And then you start introducing issues like the impact of hormones on this sort of thing. We also need to combine that with the type of exercise, of course. This starts getting really complicated, Abbie. 


I know you've done research in this particularly with things like high intensity interval training and high intensity resistance training and so on. And even if these strategies are not necessarily something an athlete is going to be focusing on as it relates to the specific adaptations for their particular sport for body composition, particularly off season or at different stages of their season or their year, these things absolutely could be and should be factored in. What are the sort of things that we should be thinking about when we're looking at advising females particularly on the body composition? What are the different things there that are the considerations given all the different types of exercise and all the complications we've discussed? Which I know is a five-hour podcast in itself.


[00:33:05] ASR: One takeaway I would have is – Women, we are designed to utilize more fat for fuel. And that doesn't necessarily mean we're going to burn fat. And that's not always the goal of exercise. But I think if we flip that and we look at what most elite athletes or non-athletes are eating around exercise, they're either not eating or they're eating carbohydrate. Because our gut, as a female, tends to be more sensitive to some of those things and causes more GI distress. Carbohydrates are more easily utilized. 


But what we see is, in that blunt, our ability to utilize fat for fuel. And so, it makes us what I call us more metabolically inflexible. And then secondarily, it increases risk of glycogen depletion if you're doing endurance exercise. And so, to me that's where supplements come in. And a lot of what we've looked at are, well, what happens if we do something like a whey protein? Or more recently, looking at essential amino acids around exercise and the impact on our performance outcomes, our exercise outcomes, but then also body composition. 


And what we're seeing is that an essential amino acid particularly before exercise can have a big impact on exercise performance, but also these adaptations. Greater lean body mass, greater strength, greater energy expenditure. But when we practically look at that, you look at nutrition products on the market, particularly related to active people, there's no protein in pre-workouts. Your gels, they're all carbohydrate. 


We see the post-workout protein, which is a message that is good. But I think for our women, we need to be looking and developing things that help them get over the GI piece, but also providing those amino acids beforehand has some clinical implications too. But when we look at kind of the everyday female athlete or active woman, that's an easy change that can have a big impact, which goes against everything that I was ever told. Like, of course, you wouldn't eat before you exercise. And have a banana. But yeah, the protein actually helps facilitate a number of things.


[00:35:10] LB: It's a really interesting area, because if we take a very – Well, not just a reductionist view, but a very narrow focus in the time course of a day and say you do this at the beginning of a workout, you must be bonkers, because that's just more calories. Why bother? 


However, the implications on metabolism after that, but also on eating, feeding behavior, can change as well. And of course, the whole metabolic response, the metabolic adaptations, which was another podcast we did a number of years ago with Layne Norton, very interesting topic that was, is interesting. 


And in some of the podcasts I've done, and I'm thinking people like Dylan Thompson and James Betts, Javier Gonzalez from University of Bath, where they've done a lot of these metabolic studies. They've looked at the compensation effect that occurs really starts to get interesting. 


And of course, I wonder if you add in the female physiology to that situation, whether or not we would see differences. And I'm guessing we would, right? 


[00:36:14] ASR: I mean, I don't know we know. But I do think – And you've brought this up a number of times, which is good. I don't think you can ignore the psychological impact and differences between males and females on eating behaviors and just some of the impact of nutrient timing. 


And so, I think – And then when you throw in you know exercise blunt appetite. So, the pre-feeding has a number of implications for not only body composition, but also recovery, and hunger, and kind of the metabolic of impact afterwards. And so, I think, often, we're looking just at the exercise bout. But when you take a higher-level look, impacting energy expenditure and fuel type. But then also exercise volume. How much are we doing? What's the cumulative effects of those things? I think those are often overlooked or not thought about if we're looking at just the acute feedings.


[00:37:06] LB: I like to humanize these things only because I've worked with lots of people and I've tried to get my head around some of the science over the years. And I hear different opinions from different people. And of course, some of those people are people who actually do research. And of course, there's lots of people who don't. And they've all got different levels of understanding about this stuff as I have over the years. I'm a lot more swished on to this stuff nowadays. 


But the reason why I keep coming back to the human being, of course, is because a lot of this stuff that we're learning in labs, this information is acquired under very specific set of conditions. But if we bring it into the real world where, for example, the stress, the anxiety, of an impending event. Let's throw that into a certain phase of a menstrual cycle. A person is feeling particularly sensitive to their body or body composition. And it may not even be – I'm thinking dancers now who may be getting a lot of external negative feedback from their dance teacher or from – Let's put this outside of traditional athlete context and into musicians and dancers who might be responding to social media. I have seen this with football players, soccer players, by the way, who have responded to public opinion about whether or not they've got a six-pack or not. And that has influenced their eating behavior. 


Of course, there's a lot in that, isn't there? That influences sort of the impact and effect and the responses physiologically. Because of course, the brain plays a role in all of this. From a translational perspective, how do you try and control for that in the lab setting and then still try and, well, tease out what you need to learn from that process? 


[00:38:54] ASR: That's a good question. I think it depends on the study. And so, some studies we're looking at individuals that have taken no medication for anxiety, or depression, or anything. And then other times we'll maybe do like a run-in phase or some familiarization so that the stress of the scenario or whatever we're doing becomes more normal. Kind of that run-in piece. 


And then depending if we're trying to mimic some sort of competitive nature, then we put similar time components or that within it. I really think it depends on the population. But then I think, first and foremost, I think our field in general is learning you don't always have to control for these things. Particularly, there's a lot of pushback now with how we study women. It has to meet a certain criteria. 


I would argue as a researcher that limits the generalizability. Instead of controlling all the things, just report them. Let's do a better job of describing, "Okay, what were those environments? What medications we're taking? At what phase of the menstrual cycle were they in? What could you control for?" 


Because especially if we're trying to translate, we don't want to have all those controls, because then you're translating to a very small group of individuals instead of just greater transparency. 


[00:40:06] LB: Yeah, yeah. Well, look, I appreciate just how difficult that is. There's a reason why a lot of males, mainly males, have been studied. Because it's just easier.


[00:40:16] LB: It is easier, yeah. And I mean, if we're being honest, our field of exercise physiology is mostly males. And I actually got to do a podcast on that. Inside Exercise, they're doing some cool – with Greg McConnell. But anyways, there's a lot of things that play into where we are in science.


[00:40:35] LB: Some of that is I think there's some practical components. But a lot of it it's embarrassing really for the field that was taken us this long potentially to get to this point. But it is what it is. But I'm just so interested in the needs and requirements of female athletes particularly the nutritional strategies that we have available. And I guess an area that is really popular just generally, in sports nutrition generally, of course. Well, there's two areas of course. One of which is proteins always. I always joke about this. If I have protein in the subject, the title of my podcast, they get vastly more downloaded. It's just a bizarre thing. 


And of course, the other one is that very polarized debate of carbohydrates. But for the athlete who needs to be functional and needs to be somebody who's going to achieve an outcome, which is basically to win the event, do the best they possibly can. Some of that stuff is less about what they look like. And it's far more about their ability to perform. 


If we look at it from that perspective, topics like protein needs for females, do you feel that there are any particular differences there? I know we talk about, with males, you know age starts to become rather interesting as it relates to protein needs. What about females though specifically? 


[00:41:55] ASR: I think carbohydrates and protein become really important for the female and a slightly different view than males. When we look at protein, we have some data in review of particularly more like the perimenopause. Kind of our – I wouldn't call older women. But we may see some of the anabolic resistance earlier in women than we do in men. And we have some early pilot data there. But trying to undercover more. Because, again, that is not only the protein amount, but the feeding of protein and the timing may be more valuable for a female. 


And then I think another kind of question that we're looking at right now as well as how that changes over a menstrual cycle. There's some early data that suggests that protein turnover and utilization is greater than the high hormone or luteal phase. But we really haven't looked at that. People say it's due to endometrial lining and some of those things. We're looking at that right now of how that changes in eumenorrheic and with an OCU’s to see does that differ? 


And when we look at across the menstrual cycle, our carbohydrate needs change as well. And I think that's where it is not to say that men and women necessarily need different amounts of these things. I think there are some differences generally. 


But when we see some of the discrepancies of women particularly across a menstrual cycle, they can be met if we increase and change our calories from protein and carb. It's really more of that do we change the amount based on our goal and our training and some of that? And so, some of those differences that we need to look at. Or how would we maybe change our kind of components there? 


[00:43:31] LB: A scenario that keeps flagging up in my head though, which I certainly don't want to not talk about, is this issue of the whole relative energy deficiency area. And I think it would be unfair to say that this is females only, because it isn't. This is an area that most definitely can be a problem for males particularly weight category athletes, thinking jockeys, as in horse racing jockeys, combat sports, particularly the lower weights that compete in that area. Definitely endurance athletes and so on. But there's no question that, with females, this is a particularly big area. 


And I'm sort of thinking particularly with a relatively young age for females, you can go past the point of no return in terms of damage that can be caused. Let's just quickly get into that. Because I think that with men, to a certain extent, and I could be completely wrong, and I'm totally open for criticism. But I think with men, there's a margin of error issue there which you can get away with. But for females, definitely not. Obviously, there's the bone health issue, reproductive health issue. What are the areas we should be considering in this regard, Abbie? And what can we do about it?


[00:44:39] ASR: Yeah. I'm not an expert in this area, but my colleague, Tony Hackney, does a lot of work. And we had collaborated on a study looking at some low energy availability in men. And you're right, they are more resilient. Meaning that they can get away for longer on a lower calorie intake compared to women before seeing some of those hormonal changes. 


I think with women, I mean, when I was younger and an endurance athlete, it was a badge of honor to lose your menstrual cycle. That was a good thing. And now we're having this conversation of like, "No. That's not a good thing. How do we address it?" And I don't think we know the long-term impacts. I think I would like to like kind of leave on a positive side is that we know that by increasing caloric intake and/or reducing some of our caloric expenditure, that those things, those impacts actually can return to normal. And there doesn't have to be – I don't know if we – Bone obviously is harder to recover from. But some of the other fertility and menstrual pieces or ovaries. 


And right now, I don't know if we have data to say that it's long-term detrimental. And so, I think it just bodes more for let's have the conversation. Let's understand our energy availability so that you can overcome those. Because I know many active women, it's not something that they're intentionally doing. But when you avoid, okay, understanding how many calories someone needs. When you avoid some of that, then we don't know if they're meeting those needs. And so, it's getting a measure of body composition, and lean body mass, and bone and understanding how many calories they're expending so that you can actually see their energy availability.


And then, yeah, eating more. And that's also where the nutrient timing comes into play. Because if you can you know prepare the body and the muscle to have nutrients before and after, then that has more of an effect and it can be more protective against some of the the endocrine changes that we see with low energy availability.


[00:46:33] LB: We've talked about all sorts of things here. And one topic that comes up a lot, because it's of great interest generally, is the whole area of body composition. The measurement of body composition also comes up quite a bit. And I've had various chats with different people about this even about DEXA and the big issues that there are with DEXA as well. And I'm thinking things like even just it might be the same brand, but it's not necessarily the same software mode. Or the firm somewhere could be different or something. I mean, there are amazing things that can influence the secret recipe that these people use. 


For you as a researcher, this is something that's going to come up quite a bit for you, I imagine. What are your thoughts and concerns about this? And what should we be aware of as it relates to measurements? 


[00:47:20] ASR: Yeah, this is probably an unpopular opinion. But I think it's ludicrous that we don't measure body composition and that we're not sharing it with our athletes and our people. Because education is power. Knowledge is power, right? 


And so, I think a lot of times we worry that if we're giving composition numbers, that it's going to support it or foster an eating disorder. But I would say not if we're educating them on what it means and focusing on things like muscle mass and limb asymmetries. 


And so, one thing we always do and highly encouraged is we want an accurate result. That's more important if you just have a single time with an athlete. And the most variable component is fluid is water. We've developed several methods of using a DEXA with a water measure to get more of a multi-compartment model to make it more accurate. 


And then even in that case, there are discrepancies with DEXA. However, the muscle mass and the limb asymmetries could be much more of a focus. And even the bone, that total body than percent fat value that is often focused on. And so, absolutely, those muscle mass values and the bone values can be really important. 


And then when we look at – I think the tracking changes is even more valuable. And really focusing. It's not about losses of fat and percent fat. It is in knowing that we know those are related to injury. Every athlete has a different set point for at which percent fat can be related to injury. But then it's really looking at muscle mass changes, and limb asymmetries, and how the body is adapting. If you are going through a high-volume season or you have multiple seasons comparing from one year to the next and looking at things like performance, and recovery, and perceived exertion. And so, it's a tool that should be implemented among sports science. And I think it's often something that people worry about. 


And then we take it outside of the athlete. I measure my body composition every nine months or so. And I have you know pre-post kids. And my students always laugh because they say, "It's not fair you have science on your side." I was like, "Absolutely, I do. I don't have to train like I used to because we can use science.


And so, I also like to say like I haven't lost muscle mass with age. And I'm lean maybe than I was in grad school because I know how to do it better. But I think it's knowing what that looks like and using it to your advantage opposed to it being a taboo topic particularly for our active individuals. Because it tells us, "Is it working? Are you doing what you should be doing to meet the goals?" And it's hard to do that if you don't have those numbers.


[00:49:56] LB: I completely agree. I think the obvious red flag for me is the heavy use of percentages. There's all sorts of problems with that. And we've gotten into that in many podcasts. I have a very memorable podcast with Professor Shawn Arent when we talked about test. Don't guess. In fact, I need to get Shawn back on to get back into these sorts of things. 


But where I'm going with this, because we're talking about females, and you've mentioned about fluid and so on, is an obvious problem area where – And I guess in the sort of the more field-based environments and particularly in the more gym-based environments, which athletes, [inaudible 00:50:34] athletes still training gyms and still have access to these things is the whole bio impedance thing. 


Biological impedance, you can maybe just give us a quick overview about what that is particularly as it relates to females and why you should be slightly concerned with what that is telling us when there are so many implications of being a female and fluid balance and so on. 


[00:50:58] ASR: Yeah. And I can share one of our papers on that specifically across the menstrual cycle. But bioelectrical impedance is just looking at or kind of resistance and reactance of fluid within the muscle. If you have changes in hydration or fluid retention, it will impact the accuracy of that device. 


I wouldn't say don't use it. I would just say be more cognizant about testing time points. And one easy way to measure women is to measure them when they're menstruating because it's low hormone, fluid is pretty even, despite fluid leaving the body. The fluid distribution is pretty even. 


And if you're not, then understanding, comparing someone during their menstrual cycle versus someone right before. So, a luteal phase. A lot of those differences are going to be based on fluid. And so, I think just good common practice is when measuring a woman, to ask where are they in their cycle. And if they're like, "I have no idea," then another step back is that all of our athletes and all of our women should understand what point in their menstrual cycle they are at. That doesn't mean you change everything. But it's really recognizing, "Okay, where are you?" And start recognizing are there differences that you feel? And then knowing that there are key physiological changes that would occur, fluid being one of them, that you can account for.


[00:52:12] LB: Now that you've mentioned that, you made me think about these fluctuations in fluid, fluid balance. Of course, the impact of that has on weight generally. But also, if we throw in carbohydrate ingestion and maybe a little dose of creatine as well, we start to really change fluid storage, if we want to be very basic about it. But also, glycogen storage and various other things. And then I guess you put that against the potential changes in substrate utilization, what are we left with in terms of understanding where we're at with all this? 


[00:52:47] ASR: Gosh! I mean, I think we have a really good understanding of carbohydrate utilization in women across the menstrual cycle. I think of anything that we know a lot about that because it changes. But I think what we don't do as – And I work some indirectly with practitioners. But is asking those questions. Like, "Okay, should we change your carbohydrate intake based on being in the luteal phase?" And so, we know that we should. It's connecting what we do know and how that impacts. Or at least addressing, "Okay. Yeah, your body composition is different last time we measured you here." What are some real changes? Is it because of some of the fluid and the carbohydrate intake? 


It's just realizing you are working with real people and they're not just numbers. And understanding there's physiological changes occur more for our women than our men in some of these kind of minutia with fluid and carbohydrate and body composition.


[00:53:42] LB: That's great. The point of asking these questions is just to help illustrate where we're at with this. Because clearly, there's things we know. There are things we don't know. And there's a massive amount of gray areas of all this, isn't it? And from a translational perspective, like you just said, I think we just – I think we still do it. We just need to be, as you said, cognizant of the strengths and limitations of the research in this area. And we just need to bear that in mind. 


In a real-world situation, we have an athlete or a subject. And we've talked about testing. How – And should we, therefore, be testing? And let's talk about body composition. That's probably the main area. You mentioned nine months for yourself. But how often should we be testing? And when is too soon also? Because sometimes there are situations where you want to be testing very quickly or very soon after another event because you're trying to achieve a result rapidly and/or bring about you know some buy-ins and behavioral aspects to this. What are your thoughts on the actual testing side of this? 


[00:54:47] ASR: Yeah. It's so dependent. I would say high level pre-post season is a really good kind of baseline to start. And then if you are trying to detect some of those quicker changes. So, for example, here, if we're doing a kind of a summer strength and conditioning program and we want to see how that changes, that's more of like six weeks. But recognizing then, if I'm doing something like six weeks, the program better be intensive. Because most of our methods can't detect much more than like by himself plus or minus three percent change or same percentage of muscle mass changes. 


And then if we're thinking about injury, that's another time point of someone you want a baseline. If someone gets injured, you may want to measure them kind of pre-surgery, post kind of surgery, before they start rehab or some of those things. But generally, I would never do more than every four weeks. We've done here with some of our elite basketball players we're seasoned. I mean, they're playing like every other game, traveling. Trying to hone in on how much muscle mass is lost. Or how do we help them with longevity of the season? You might measure them a little bit more quickly. But not as a measure of, "Oh, what percent fat are they?" It's really like how are they changing from the previous time? Are they in a positive or negative direction? So that we can help facilitate kind of injury prevention. If you have a very sophisticated device, four weeks maybe? And then I would say, most often, we wouldn't need to do it that frequently. Six weeks and then really pre-post season. 


[00:56:15] LB: Yeah, great, great. And then just a sort of segue slightly into a slightly different area, we talk a lot about protein, and carbohydrates, and calories. And now we're talking about males, and females, and so on. But some of these people do still want to follow very specific dietary preferences, like vegan, or plant-based, or the other side of it of course is the rather extreme stuff because they believe avoiding carbs altogether, for example, will benefit their body composition. But particularly for females, is there any – I mean, this is a very generalized sort of area not specifically aimed at any particular type of sport or whatever, but just generally for body composition. What are the key areas that you feel are relevant for those that are maybe more down sort of plant-based, or vegan, or vegetarian type pass? Is there anything there that's relevant for females that we know of? 


[00:57:18] ASR: I mean, I think just protein timing throughout the day is going to be really important. And there's some good data on carb to protein ratio that sustaining something slightly lower for a woman is more optimal for body composition. Obviously, if you're a vegetarian or vegan, that's a little bit harder to do. 


And then the last point – We don't have a lot of time left. But the last point I would say is there's some really fascinating data that longer windows in between meals actually exacerbates the effects of energy availability and RED-S. And so, oftentimes, it's just making sure like meal frequency is happening, than kind of intermittent fast would not be something that I would recommend particularly for a woman.


[00:58:00] LB: Yeah. No, that's great. I mean, look, I throw that in just because it's such a popular area. It still comes down very much to individual situations, doesn't it? But look, there's so much stuff that we've talked about. It's just been fascinating to delve into this topic with you, Abbie. I know we're out of time here. But is there anything you wanted to end this conversation with? Just generally speaking. Maybe some just sort of sum up points about your thoughts particularly for body composition in females and them being athletes, for example? Is there any particular points you want to leave us with? 


[00:58:33] ASR: Recognizing at what point in the cycle? Not to be afraid of the numbers. Really educating women on what those numbers are and what they mean. It would be really valuable. And then on the nutrition side, there's lots of more resources coming out on just recognizing that there may be differences. And so, kind of continue those conversations.


[00:58:50] LB: Yeah, excellent. Well, thank you so much, Abbie. We've bounced around on all sorts of topics there. But that's the way these conversations go on this podcast. And it's been really interesting. There are all sorts of papers that we've discussed and then papers that you've also referred to. I'll be sure to add those into the notes here so people can read up on everything. 


But I just wanted to say thank you so much for your time. I know you're super busy. But it's been great to have you back for a chat. And there was lots to get out of that conversation. So, thank you so much, Abbie. 


[00:59:22] ASR: Yeah, thanks so much to me. It's great to see you virtually. Hopefully we'll run into each other again. 


[00:59:26] LB: Oh, I'm sure. Yeah. Well, we'll see what the world's going to do. But conferences will be necessary. 


[00:59:32] ASR: Absolutely. 


[00:59:32] LB: Thank you so much, Abbie. 


[00:59:33] ASR: Thank you. Take care.


[00:59:34] LB: Thank you.