Optimize Women’s Exercise According to Hormone Levels, with Dr. Stacy Sims

Today we are taking on a revolutionary and provocative topic that I suspect will be quite liberating for many of us women (and practitioners who work with women) – a deep dive into how to optimize exercise training and performance during pre-, peri-, and post-menopause. This topic is of great importance to me as a cyclist and, I have to say, there’s nuance in the way we women should approach training that is hormone-dependent. My guest Dr. Stacy Sims is a huge talent and a tremendous gift to our community — listen as we discuss why women need to train differently than men, including specifics about protein intake, fasting, hormone replacement therapy, and what types of training are best depending on where you are in your cycle or menopause journey. Grab a pen, you’re going to want to take notes! ~DrKF

Optimize Women’s Exercise According to Hormone Levels, with Dr. Stacy Sims

When it comes to optimizing exercise training, it’s time to remind ourselves that “Women Are Not Small Men,” as my guest on this New Frontiers podcast episode, Dr. Stacy Sims explains. Dr. Sims is an expert exercise physiologist and nutrition scientist, a researcher at Sprinz AUT Sports Performance Research Institute, and the author of more than 70 peer-reviewed papers. We discuss sex differences in training and nutrition, protein intake, timing of nutrition pre- and post-exercise, the best types of training, and how this impacts longevity in women based on where they are in their hormonal cycle.

In this episode of New Frontiers, learn about:

Dr. Kara Fitzgerald: Hi, everybody. Welcome to New Frontiers in Functional Medicine where we are interviewing the best minds in functional medicine and beyond. And of course, today is no exception. I am really excited to jump in with this woman, Dr. Stacy Sims.

But before I tell you about her and we jump into what’s going to be an amazing conversation, I just want to give out … Shout out to our lovely diamond sponsors for taking good care of this podcast and just keeping it going throughout the years. This is Rupa Health. Anybody who’s practicing medicine in the functional integrative space needs to check out Rupa Health because they make laboratory testing easy. They make the complex, functional laboratory testing easy for all of us. Actually, for us as clinicians, for our support staff, as well as for our patients. That’s Rupa Health, check them out, there’s a link in the show notes.

And also Biotics Research. I’ve been taking, prescribing, recommending biotic supplements for years and they’ve actually been around for decades. They produce high-quality products. They’re designed, they’re creative. My friend and colleague, Dr. Alex Vasquez, is involved in a lot of their product designs. And their ingredients are really impeccable and high-quality. So to both of my sponsors, thank you, thank you, thank you.

All right. Now onto the podcast. Let me tell you about Dr. Sims. She is a foreword-thinking, international exercise physiologist and nutrition scientist who aims to revolutionize exercise, nutrition, and performance for women. Amen to that. She’s directed research programs at Stanford, at Auckland University of Technology, at the University of Waikato, if I’m saying that right, you can correct me later. Focusing on female athlete health and pushing the dogma to improve research on all women. This is essential. At Stanford, she translated earlier research into science-based laypersons’ book, Roar, to explain sex differences in training and nutrition across the lifespan. Challenging existing dogma for women in exercise, nutrition, and health. This paradigm shift is the focus of her famous TEDx Talk titled, “Women Are Not Small Men”.

Her vast contributions established her as the premiere expert in sex differences in training, nutrition, and health. And with that, she’s repeatedly on top 10 lists of physiology and nutrition experts really around the globe. She’s published a ton and she’s still publishing. She’s got 2023 publications out. She’s prolific, more than 70 peer-reviewed papers. She’s written books. Again, TEDx Talks, et cetera, et cetera. She’s a sought-after speaker around the globe and really focusing in the sports faith.

She’s a Senior Research Associate at SPRINZ-AUT University and is on the advisory board of cutting-edge companies and also runs her own business. And, as we were just talking about, she’s a mom as well.

Stacy, Dr. Sims, welcome to New Frontiers.

Dr. Stacy Sims: Thanks for having me. I feel like we used up the entire time by you just reading my bio.

Dr. Kara Fitzgerald: You’ve done a lot. I mean you’ve done a lot. Your career is extremely impressive. I am so glad to have found you and to be able to highlight you on the show because I know people are going to be very interested in your message. You know, fundamentally, women are not small men.

You are an athlete and I’m particularly interested in this because I am an athlete too and I was competing in college, I don’t anymore. But this got you on your career journey. So you were a rower, I believe, in college and you started to observe differences between men and women-

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: … and that led to your focus. I mean just tell me a little bit about your story and how you came to that and what you saw.

Dr. Stacy Sims: Yeah. So I was always that kid that asked why and when I got to university and was rowing and some of the things didn’t make sense. I was also in ex phys. I was like, “Okay, well I’ll ask there why these things are happening.” And I kept getting the answer, “Doesn’t matter. You’re just like men.” Like in metabolism labs, being one of the only women that were fit enough to be crazy and to do some of the two-hour runs on the treadmill and my results were different enough that they would throw them out or call them an anomaly. So then I was like, “Wait.” I’m the daughter of a military officer. I follow the standardization. I know how to follow the rules. So it just didn’t add up.

So as I started digging a bit more, I’m like, “Wait, there’s nothing out there really for women.” You read the textbooks and they always refer back to the cis man. And even like medications and everything, it’s all based on that standard, 180-pound white man. And when you start looking and it’s like, “Wait a second. You’re telling me that I need the same things as a 130-pound woman as a 180-pound guy?” Just didn’t make sense.

So being inquisitive and pursuing more athletic things in my life, having the availability to go and try to find those answers to apply to myself as an elite athlete and my teammates. And then when I stopped racing, being able to help teammates who became coaches. And really trying to get people to understand that what we are now acknowledging as a status quo is not good enough for women because that research hasn’t been done for us and we’ve just been put in this little box. And you can see it in the fitness world, too.

I mean you see women who are constantly injured, over-trained, just sick, and they’re following the same kind of coaching protocols, nutrition protocols. And they’re just not getting the results. And people say, “Oh, well you’re not doing it right.” Or women blame themselves. “I just can’t do it. I’m not good enough.” And so it’s that internal, negative conversation that keeps pushing and pushing women to have self-doubt and not achieve what they can when actually, it’s the protocols. And the protocols that are being applied and even the language and conversations that are around the fitness world and how to be strong and how to eat right. It’s just developed out of this sport endeavor of aggression and power and infallibility which is all those male traits.

So it’s been interesting over the past couple of decades to see how bad it’s gotten. And now that we’re having more of a global voice that, yeah, women are not small men and we need to do something about it. Seeing maybe in the past four years this global uptick of, “Okay, it isn’t good enough to treat our women like this. Let’s look and see how we can treat them better.”

Dr. Kara Fitzgerald: It’s a liberating statement. Women are not small men. It’s really liberating. When I first heard … It was quite a while ago that I came up on your work and that term. And I’m like, “Women are not small men.” It is, it’s liberating.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: We’re different. How are we different? So what did you observe and then what’s in the literature and what other questions are you curious about? Like how are we different?

Dr. Stacy Sims: Growing up from an academic standpoint in the academic sport literature, there really isn’t anything that digs in. So being inquisitive, looking at other literature, and then when I was doing my post-doc with Marcia Stefanick and she was in the Women’s Health Initiative and talking about all of these sex differences and stuff, start digging in, you’re like, “Hey, wait a second. There are sex differences in utero.” Which is the identification of XX versus XY. And how a male embryo is not as resilient to stress and starvation as a female. And how those differences can be translated after birth.

And then you’re looking at what’s happening at the onset of puberty and we’re seeing that you have that expression, epigenetic expression of testosterone that makes boys get leaner and stronger, more aggressive. Their bones get stronger, they have different muscle fiber uptake. And then what happens with girls is their hips widen, their shoulders widen, their center of gravity changes, their body composition increases body fat, and they get their period. But no one talks about that. No one talks about how we should be treating our girls and boys differently around puberty to enhance functional movement, enhance skills, enhance our ability to run, to jump, to keep girls in sport, keep girls happy playing on the playground.

So it’s just all the way through from before birth and even as we look at the aging literature. Because women don’t age like men do in a linear fashion because we have peri and post-menopause, right?

Dr. Kara Fitzgerald: Right.

Dr. Stacy Sims: So when you start really looking from that big picture, you go right back to basic biological research and go, “Hey, everything we know really, if we look at sex differences.” But not only that, when we look at early studies, they’re all male mice. And so that doesn’t really translate. So you can really pick it apart all the way back to the beginning of actual scientific method and scientific design.

Dr. Kara Fitzgerald: Wow. It’s so interesting. I mean it makes sense that female embryos would have better resilience because we’re going to be carrying babies-

Dr. Stacy Sims: Right.

Dr. Kara Fitzgerald: … keeping the population surviving. So just from evolution 101, you could infer there may be some little extra that we’ve got at that time.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: But yeah, you’re right. I mean our bodies change radically. I mean … So I want to get to talking about peri and post-menopausal women but I just have to ask you, how do we address girls moving through puberty and all of those changes that … When you were describing it, I was just sort of flashing back to my own body changes and you don’t want to move. I mean when these changes are happening, when we start getting our periods and they’re usually wonky and-

Dr. Stacy Sims: And the hormonal shifts.

Dr. Kara Fitzgerald: Yeah.

Dr. Stacy Sims: As a mom of a 10-year-old, I’m viewing. Right?

Dr. Kara Fitzgerald: Yeah.

Dr. Stacy Sims: I think part of it is the cultural part where culturally, it’s been so taboo to talk about having a period, right? And that stems from a long time of men not understanding it, women having to go to menstruation tents and all sorts of things, right? So trying to get it normalized and having girls understand that this is just basic physiology. And it’s normal and we need to talk about it. We need to be able to support it. And there are small pockets in the Western world that are having free period products in the schools but it’s not until the high school. So we’re starting to see more uptake in the high school but it’s the younger set.

And so from a sporting perspective, that’s the way I’m trying to enter it. Where we look at girls and boys soccer or swimming or something like that and you’re starting to see these changes inherently where the boys are getting faster and the girls are kind of dropping off. So talking to the coaches, saying, “Hey, let’s look at the dry land training. Let’s look at the functional movement training.” And if we want to have progression in the girls, we have to let them understand that we need to do more functional training and understanding our mechanics because those are changing.

Now for the boys, functional training is that they have control of these muscles that are getting bigger and stronger. And for the girls, it’s functional training so that they get more control from a biomechanical standpoint. But in fact, it’s pretty similar in the training. It’s just why we are doing it. So we get that education piece, it starts to normalize it. And if we’re normalizing it in the sport environment, then it becomes normalized in the general environment because sport is such an icon for role models and how things should be done.

Dr. Kara Fitzgerald: Yeah. Yeah, yeah, yeah, yeah. And you are going to have a little more body fat or your body’s going to move differently and feel differently. And yeah, your hips are wider and support … And that’s all as it’s supposed to be, you know this is who you are.

Dr. Stacy Sims: Right. That’s why I love the Olympics, the Olympic cycle. Because like ESPN always puts out a body image or a body issue and it’s profiling all the different body types and all the different sports. So you have the availability to see what does an Olympic track cyclist look like versus an Olympic track runner. Or what does a gymnast look like next to a triathlon, right? So you see all these different successful body shapes and sizes. And so being able to show, not everyone fits into a 5’7, 110-pound frame type thing that we’ve been so conditioned from fitness and modeling stuff. And not every guy has to be six foot tall and super muscly. Right? Because there’s so many different body types that are successful in these different sports. And-

Dr. Kara Fitzgerald: You know-

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: … from my personal journey, becoming a competitive cyclist, because I’ve got these large … You know I’ve got legs that are fast-twitch and bigger, was one of the most … It was so liberating and validating to sort of see my body’s purpose and that it’s good that it looks this way. My sister on the other hand, was really … Was actually like the 5’9, super slender model. And I wanted that and I did … It took sport, it took competing, for me to get the body that I have and to recognize it as badass as it … You know, for what it was.

Dr. Stacy Sims: Yeah, exactly.

Dr. Kara Fitzgerald: And it was a huge … It was a very important moment. And I could see we could use this across with girls and women of all different body shapes.

Dr. Stacy Sims: I tried to explain it to my daughter because a lot of her friends are more petite in stature than she is. She has really long limbs because both my husband and I have long arms and legs and so does she. She wants to do gymnastics. But her center of gravity is different from all her little friends are really good at doing handstands and round-offs and that kind of stuff. So I’m explaining to her, “Hey, it’s not that you can’t do it. It’s your body’s center of gravity and how long you are isn’t going to make you as successful in gymnastics as your friends who are smaller. But let’s look at soccer, let’s look at running.” And so she’s excelling in those things that match what her body’s really capable of doing and having me as a mom, I’m able to explain it. And so it’s like that education piece. But it’s right. It’s like you find that niche where your body just loves to do what it does. And then you feel really powerful.

Dr. Kara Fitzgerald: Yeah. It’s exciting and it’s liberating and I think it’s so important because as you said in the very beginning, we can internalize. Like my body wasn’t okay. I wanted it to be something that it wasn’t and it was a really important moment and truth for me to learn. And it sounds like for your daughter as well, to begin to embrace who she is.

Dr. Stacy Sims: Right.

Dr. Kara Fitzgerald: I’ve got one more question then I want to jump on. One more question in this arena. So we see kids and I think this because I’ve just seen this in my practice, who are doing gymnastics and who have very low body fat and become … We see anemia pretty commonly. We see amenorrhea, et cetera. What are your thoughts there? How are we addressing that?

Dr. Stacy Sims: So again, it’s the culture, right? So we look at what is the culture within most of gymnastics. It’s training. You see girls who are six, seven-years-old and they’re getting into five or six-hour training days. And they’re very conscious of how they move and they’re being told that they have to be able to be a certain look and have a certain flexibility. And so it’s all about the body image. And in that, it’s the hard training.

And when you start gymnastics so young and puberty starts … You start seeing some of the normal changes around eight-years-old. And so girls become very conscious that all of a sudden, wait, I’m not as thin or as compact as I was. So what do I do? And unfortunately, one of the almost automatic responses is to not eat because there’s that association of calories in, calories out. It’s still that undercurrent. I mean I’ve been in different cultures where they’re like, “You need to not eat as much because you’re putting on too much weight.” And coaches will say this. Or they’ll compare gymnast to gymnast. And it’s like, it’s just that ingrained thing.

Now, with the whole Athlete A documentary that came out and the whole inquisitiveness into USA gymnastics, the culture is being exposed. So we’re seeing more and more of, we need to make sure our girls are healthy. And we’re seeing more role models that don’t fit that typical profile of a gymnast which is fantastic. But again, it’s making sure that we teach coaches and we teach the girls how to stay out of low-energy availability. And we need to fuel our bodies for what we are doing because we would not drive a car down the road on E (empty) and expect it to go fast. Right? And so it’s using those analogies that people will understand. We have to fuel for what we’re doing in order to get the adaptations. If we’re fueling, we get this adaptation and we keep our body healthy.

Dr. Kara Fitzgerald: And parents, we need to pay attention. I’m going to be watching. I mean I definitely want my daughter to be in sports. She’s super physical and active. But yeah, I’m going to be watching for those messages like a hawk. I mean I’m just not … Ugh. I don’t even … Yeah. It’s … She’s still pretty young. It’s not a place that I’m excited about going but I’ll absolutely go there with her and make sure that she’s in a super healthy environment.  You know, as you’re doing with your daughter-

Dr. Stacy Sims: Yeah. I’m worried about the teen years and they’re fast-approaching. And I’m like, how much education and body positivity can I give in these early years that will carry through it?

Dr. Kara Fitzgerald: Yeah. She’s … We’ll circle back. We’ll circle back-

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: … in a couple of years and have this conversation again.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: So now let’s talk about women who are … Let’s talk about the moms now in this audience.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: Let’s look at maybe … A few comments on premenopause but peri, post, I want to just get into that about how we should be training. So the women, how should we be training? Yeah. I was going to say differently from men but we don’t even have to go there.

Dr. Stacy Sims: Just differently.

Dr. Kara Fitzgerald: How should we be training? Yeah.

Dr. Stacy Sims: Yeah. As I said earlier, how we don’t talk about puberty and how these changes are happening with our young girls. Well no one really talks about what’s happening in perimenopause which is actually the other end of puberty or instead of hormones coming up, they’re starting to go down.

So if we look at estrogen, progesterone, testosterone, primarily, estrogen and progesterone, they affect every system of our body. We have our receptor sites that are affected by these hormones. So when we start having this downturn of estrogen, progesterone, or a misstep in our ratios, we start having different signaling. And we start losing sensitivity of our estrogen receptors. We start having gut microbiome disturbance because we don’t have as much of the gut bugs to metabolize the estrogen and stick it back out. So there’s so many of these changes that are happening internally.

So if we look externally, what can we do to support our body through this? We need to look for an external stressor that is going to apply the same kind of signaling for adaptation that our body will do without these other hormones. What I mean by that is if we look specifically at skeletal muscle. So we know that estrogen specifically is tied to the stem cell of skeletal muscle. And when we start having a downturn of estrogen, then we don’t have as much satellite cell signaling. So this is why we don’t … We start to lose lean mass when we hit perimenopause and it’s harder to build mass.

The other thing with it is estrogen is tightly tied to myosin which is one of our important filaments for muscle contraction. So if we don’t have enough estrogen, or we have too much estrogen, then we have a misstep in how strong our muscles are contracting.

And then the third thing that estrogen is responsible for is acetylcholine and how much acetylcholine is there to depolarize and cause that muscle contraction stimulus.

So if we’re looking at those three really basic biological, physiological responses that estrogen is responsible for, then we have to look externally. Well, what do we do that’s going to create a really strong muscle contraction that’s not only going to keep those nerves firing how they should and activating those muscle fibers, but also give the signal that we need more muscle fibers?

So this is where we look at resistance training. But we’re not looking at our eight to 12 or 15 reps that everyone talks about hypertrophy. That’s not what we’re after. We’re after a central nervous system response. We’re after women to lift heavy. So that’s that zero to six rep range with really good form. Because we want to have that external load that’s a central nervous system response. So we’re having the nerve come down and be like, “Oh my gosh, I have to recruit a whole bunch of muscle fibers to overcome this load. Not only do I need to have a really strong contraction, so I better get myosin on board. So I have to have more acetylcholine. So the body’s prepping it all. But I also need to have more muscle fibers themselves to activate. “So if we’re lifting heavy, we’re getting a central nervous system response that’s going to create that adaptation rather than relying on estrogen to then stimulate the satellite cell and the myosin and the depolarization.

Dr. Kara Fitzgerald: That’s so interesting.

Dr. Stacy Sims: So it’s really looking like, how do we mitigate and breed a training environment to create that stress that our body needs?

Dr. Kara Fitzgerald: Awesome. Are we anticipating … Are we okay with some muscle loss during this time? Or do we want to be really fighting for maintenance? You know to be … Yeah, go ahead.

Dr. Stacy Sims: Yeah. So it’s … You can definitely build. People are like, “Oh, I’m postmenopausal, is it too late for me?” I’m like, “No, it’s not.” It’s never too late. We just have to look at … In perimenopausal, we have such a sympathetic drive because the body doesn’t have as much parasympathetic response because we don’t have progesterone coming onboard, as much as we used to with more anovulatory cycles. And we have an increase in our baseline of cortisol because the body is stressed and misstepped in sleep.

So if we take it from a lot of people are like, “Oh, I want to go to crossfit and I want to go to these bootcamp classes and I want to do these HIITclasses,” and nothing’s working for them, they’re getting more tired. They’re getting more tired but wired, sympathetically driven. And it’s not about stopping that and not about not progressing. It’s looking at it and going, “Wait, it is not polarizing enough to create the responses I want.”

So again, we look at that heavy resistance training to create that muscle adaptation. It also helps with bone. And then from that cardiovascular standpoint, we need to look at really having high, high intensity. Not this moderate intensity stuff like your 45 minutes circuit classes or bootcamp or spin class or even some of the MetCon and CrossFit-type classes. We need to look at 85 to 90 percent of your max for one to two minutes if you’re doing high-intensity interval training with adequate recovery so that you can do four or five sets of that. But specifically, we need to look at that super maximal sprint and interval training where you’re doing 100 to 110 percent for 30 seconds or less. Because if we’re doing that top, top end, which is really, really hard, we have a follow through of growth hormone and testosterone responses, as well as a massive antioxidant response from that high-intensity. Which is exactly what our body needs when we’re in perimenopause.

Dr. Kara Fitzgerald: God, that’s fascinating. So we’re turning the volume up big time, wow.

Dr. Stacy Sims: Intensity but not volume.

Dr. Kara Fitzgerald: Right, okay, intensity.

Dr. Stacy Sims: We don’t want a lot of volume.

Dr. Kara Fitzgerald: Yeah.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: Right. Right. Fascinating, okay. So when you-

Dr. Stacy Sims: When you’re looking at improving sleep, improving body composition, improving metabolic health, all of these things that start to have a misstep when we hit perimenopause, especially late perimenopause. We drop the volume and we’re looking at two sprint interval or two sprint interval with one high-intensity interval training, so longer intervals. And two to three heavy resistance training sessions. But those sessions aren’t long. The heavy resistance training might be 20, 25 minutes because you’re going and you’re focusing on compound movements. So you’re getting total body workout. And then you can follow it up with five to six, 30-second sprints and you’re done and dusted within 45 minutes. All off-

Dr. Kara Fitzgerald: Doing both cardio, doing some HIIT, thrusting, resistance.

Dr. Stacy Sims: Yeah. So you do resistance and then you follow it up with a HIIT or a sprint. Or you can separate them out if you don’t want to spend that much time or you’re like – I’m too tired from lifting to do proper sprint stuff. And it’s not about spending hours and hours in the gym. It’s being very purposeful, planning it out, going hitting it hard, and then recovering.

Dr. Kara Fitzgerald: And how many days a week are you doing this resistance protocol?

Dr. Stacy Sims: So two to three times of resistance training. And then you have two, maximum two sprint interval training sessions or maximum three high-intensity interval sessions a week. If you’re bookending some resistance training with some sprints, then you’re taking care of two in one day. So it might be four days a week total. Some people are like, “But I’m endurance. I love going out for my long walks.” That’s absolutely fine. And as an ex-cyclist, just like you, not competing but I love riding my bike. It’s not the bread and butter. It’s my soul food but my bread and butter is resistance training and interval stuff.

Dr. Kara Fitzgerald: Awesome. You’re answering my questions. That’s awesome. Because yeah, that’s my happy place, my bike. You know for-

Dr. Stacy Sims: Exactly.

Dr. Kara Fitzgerald: Listening to podcasts and-

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: … just kind of feeling good. You can do HIIT, for sure. But I love it. So kind of a brief, maybe four brief chunks of intensity, resistance, and cardio.

Dr. Stacy Sims: Yeah. Here’s a go-to for you as a cyclist, okay?

Dr. Kara Fitzgerald: Mm-hmm.

Dr. Stacy Sims: So winter, winter training, in the gym, you do deadlifts and squats. So you’re doing maybe five by five deadlifts with three minutes between. And then you’re going to go into two by three to five heavy squats. Finish that up, get on one of the bikes and do your sprint interval training. So you’re taking the fatigue from the lower body work and putting it into your cycling mechanics. But if you’re not someplace where you have to be inside, well you do your heavy lifting and then you go out and you ride up the hill.

Dr. Kara Fitzgerald: Yeah.

Dr. Stacy Sims: And you’re getting the intensity from the hill ride and you’re taking the fatigue from the deadlifts and the squats and putting it into the muscles so that they now have to learn how to fire when they’re tired and get that activation or increase lean mass.

Dr. Kara Fitzgerald: I love it. I love it. It’s great. How would you approach this for the non-athlete. Like I’m thinking about my mom who would be like, “Yeah right.”

Dr. Stacy Sims: Yeah. I know. My mom too.

Dr. Kara Fitzgerald: Or my sister, or my sister for that matter.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: How do you start on this journey? You can do the same thing but just where you’re at? I mean-

Dr. Stacy Sims: Yeah. So if we’re talking about resistance training, heavy is relative, right? It could be that you’re doing body weight stuff initially but then you put a backpack on with a kettlebell in it. It could be a five-pound kettlebell. And then you work your way up. So then you’re doing all of your body weight movements with a little bit more resistance. And this tends to work for so many people who are like, “I don’t want to go to the gym. I don’t feel comfortable in the gym.” But then you might find that hey, I’m getting stronger and the backpack isn’t working. So then maybe we’re going to go outside with the backpack and we’re going to do lunges up the hill. Or maybe we do our walk and we do our stairs or our hill and at the top of the hill we take the backpack off, we take the kettlebell out, and we’re going sumo squats with the kettlebell. So it’s being interactive with your environment and not making it overcomplicated by having people go to the gym, into that very masculine environment, if they don’t feel comfortable.

But resistance training is so, so important for women who are 40 and older. Actually, for all women but really, really important when we’re looking at what’s happening from a longevity standpoint. Which of course, you know. And we’re seeing more data come out for women who are in their 70s, 80s, and taking them and doing them in circuits to increase resistance and increase lean mass. But instead of doing eight to 12, they’re doing the relative to them, heavy power training and they’re getting better outcomes. Not only from lean mass development but better proprioception because their body has to recruit more fibers and be more spatially aware. So then if they step off the curb wrong, they don’t fall and break their hip. They’re like, “Whoa, I’ve got the balance to catch it.”

Dr. Kara Fitzgerald: Oh, that’s so fabulous. Great. Great, really inspirational. What are your thoughts on Zone 2 training? There’s a lot of chatter here in the States about Zone 2. It’s just gotten popular with some influencers. And you’re focusing on doing resistance and high intensity, layering it happy activities which were probably more Zone 2. What do you think? Do we need to do that? Is it a priority for women?

Dr. Stacy Sims: Not at all. So if we look at Zone 2, the main idea behind Zone 2 is to increase mitochondria, increase mitochondria metabolism and efficiency. Women by the nature of XX, we are already born with more of the proteins within mitochondria for doing fatty acid metabolism. We also are born with more ability to handle oxidative stress. So if we’re looking at what is Zone 2 doing, supposedly increasing our metabolic flexibility, increasing our fat-burning, increasing our mitochondrial responses. By the nature of being a woman, you already have that. We don’t have to spend hours and hours on Zone 2 trying to increase our aerobic functionality. And this is that whole … I get really a bit frustrated when people are like, “But so and so said so.” And it’s like, “Yeah, but it’s a male coach following male protocols.” And you have to understand that coaching is still about 20 years behind the science. It hasn’t caught up yet.

So if we’re talking about mitochondrial development and all this aerobic metabolism, it’s based, again, on the cis male. But if we look at women’s muscle and women’s muscle function, we fuel differently, even before we’re in peri and post-menopause by the fact that our bodies will rely on blood glucose and fatty acids and slightly tap into liver and muscle glycogen. And so the goal of Zone 2 is not to tap into that liver and muscle glycogen, it’s to really tap into the fatty acids. But we’re already there.

So there’s so many sex differences that go into how our bodies fuel, how our bodies are aerobic, how our bodies are looking at mitochondrial development. And men should be jealous of women because naturally we’re already there. So we don’t have to do all that long stuff.

Dr. Kara Fitzgerald: What if we’re diabetic? Or what if we’re pre-diabetic? Then are we leaning into some of these training regimens or are we still going with what you’re outlining?

Dr. Stacy Sims: Yeah. So when we’re looking at some of the epigenetic changes that happen with the high-intensity, we actually see that there’s more of GLUT4 activation and translocation. So for people in the audience, GLUT4 is a specific protein gate within muscle that allows glucose to come in without the use of insulin. And we see estrogen, again, is tightly tied to it. So not only do we need to really focus on that high intensity for metabolic control and blood glucose control. But when we’re younger and we’re in that pre-diabetic or diabetic aspect, we always want to look at how are we going to create this epigenetic change within the muscle to be able to use and pull in more of our blood sugar instead of using insulin.

So again, it’s looking at high intensity to create that stress where the body’s like, “I need more fuel right now. I don’t have time to tap into fatty acid. I need that right now.” So it creates this greater translocation to open up those GLUT4 proteins to pull more in. And then the response post-exercise is now you have more coming into the liver, more coming into the muscle, and it’s less in circulation.

Dr. Kara Fitzgerald: Yeah. I mean I can … For many of us, I think, we know that the little window where indulgence in carbs is post-event because you’re just really more efficient.

Dr. Stacy Sims: Exactly.

Dr. Kara Fitzgerald: Yeah, awesome. Good news.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: The whole Zone 2 training did not exactly thrill me but …

Dr. Stacy Sims: Nah. No.

Dr. Kara Fitzgerald: What else do I want to ask you? Okay, so then you’re talking a lot about the changes in hormones and how we can actually … So we’re dropping off. We’re in perimenopause so they’re wonky and kind of in perimenopause and then they drop off in menopause and post-menopause. Where are you at with hormone replacement therapy in this model? I mean it sounds like you’ve just outlined a protocol for us to be able to move through it without HRT, but what about using HRT? Do you have thoughts on that?

Dr. Stacy Sims: Yeah, got lots of thoughts on that. Because like I said, when I was doing my post-doc at Stanford, I was working with Marcia Stefanick and she was one of the PIs on the Women’s Health Initiative that initially caused the scare of taking it all off. And what people did not understand about the Women’s Health Initiative is that it was done on late post-menopausal women. So women who were 10-plus years away from that one point in time in menopause. Whereas you look at the UK million women’s study that was done on early post-menopause and late perimenopause women. Completely different outcomes with menopause hormone therapy.

So when we look at what it is, we have to realize that one, our body is not metabolizing these hormones the same as our natural state, right? So our endogenous hormones are metabolized differently from exogenous hormones. But menopause hormone therapy is a therapy. And it is useful for getting through perimenopause, into post-menopause. Especially if you have really bad vasomotor symptoms, you have a sudden bone loss, so you’re at risk for osteoporosis. It’s not good for body composition change. It does not stimulate lean mass development. It slows the rate of loss but it does not naturally do what our endogenous estrogen used to do by creating muscle turnover and increasing lean mass.

So there are caveats within it that need to be discussed with what it can and can’t do for us. And we have to sit down with our physician if we’re really not sleeping, we’re always, always tired, brain fog, really bad vasomotor symptoms, anxiety, depression. There are therapies that you can use and if they’re not working, then yeah, try a menopause hormone therapy. It’s there as a therapy to help. It’s not there as a stopgap. It’s not a pharmaceutical that has been advertised in Europe as stopping female deficiency hormone … I guess, what were they calling it? Syndrome? Or they’re calling perimenopause a disease. It’s not about that. It’s a therapy and it’s there to be used when and if you need it.

But also, don’t make that the first step either because there are other things that you can do. You can do training and nutrition interventions. You can try Venlafaxine which is an SSRI for vasomotor symptoms. You can definitely look at using some adaptogens. And again, if all that still is not enough, then yeah, add it in.

Dr. Kara Fitzgerald: I think it’s a point that I want to underline that it’s not going to change body composition. It’s not … We still need to get in there and do the effort.

Dr. Stacy Sims: Yeah. Especially for the visceral fat.

Dr. Kara Fitzgerald: Yeah. Yeah. So let’s move on to another conversation that you’ve had quite a bit, what we should be eating. And I want to start first because we’re talking about workouts, muscle, with protein. Another really huge topic lately. We just wrote a blog about it on my space. But just a lot of conversations around it. Either you need to drop protein like a stone because protein causes cancer. I think that that’s been challenged. Or you need to eat your weight in protein. I mean what do we women, again, peri and post-menopausal, or peri, meno, and post, need to be thinking about with regard to protein?

Dr. Stacy Sims: Yeah. So we become more anabolically resistant as our hormones start to change. And specifically, it’s the anabolic response to building muscle, right? So we’re looking at estrogen, like I was explaining earlier, really helps with lean mass development.

When you’re looking at doing all the heavy resistance training and the high-intensity work, we need to follow that with good amounts of protein in order to compliment that stress, to really get the responses of lean mass development. So for women who are in their early to mid 40s, we’re really looking at that … I’m sorry I’m in metric but I’ll try to convert. Around that .8 to one gram of protein per pound of body weight. And we want to evenly divide that. So we’re looking at 30 to 40 grams at each meal, around 15 grams at each snack. And training becomes part of that as well. So if we’re looking at doing our training in the morning, then maybe we’re splitting our breakfast protein before and after.

But it’s really essential that women are keeping that amino acid coming up and circulating. One, because we have a higher amount of amino acid use and oxidation when we’re getting into this sympathetic state because our body’s like looking for fuel. We also know that we need to have more to increase the leucine threshold within the muscles so that we are actually getting that lean mass development and that strength development. And if we’re looking at the literature on aging as well, they’re showing that women who are eating more protein have better lean mass and they have better quality of life, same with older men. So it’s the protein intake that becomes a really, like you said, it’s a polarizing story because of a few people who have come out and said, “No, it causes cancer.” But if you’re looking at specifically what’s happening from the full body response to exercise and protein, yeah you’re going to have an increase in the mTOR signaling but that’s reparation. So you need the protein to come in to help repair and build the muscle, right?

So yeah, I’m like, “I really can’t hang my hat on some of those don’t … You really have to have a low protein diet” when there’s so many beneficial mechanisms that come with having that equitable, at least .8 grams per pound of body weight, just as your baseline.

Dr. Kara Fitzgerald: And that translates to like about 1.7 to 2.4 grams per kilogram.

Dr. Stacy Sims: Per kilogram. Yeah.

Dr. Kara Fitzgerald: Okay. Which is right up there with an athlete protocol.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: So you’re not backing off with protein recommendations at all. And you mentioned … Leucine. So you’re talking about the branch change amino acids. What sources of protein are the top? Are the ones that you would recommend?

Dr. Stacy Sims: That depends on what people like and eat. I mean you have the whole plant-based aspect and people are like, “I’m just using legumes and seeds and pea protein isolate. And then you have the animal side of things where you’re getting all sorts of protein from all different animal stuff. And that’s fine. It’s whatever your choice is. But you really want to make sure that it’s high-quality protein. So if you are vegan, then you’re looking for your peas and your seeds and your nuts and your tempeh. Tofu is kind of iffy because of some of the effects that it has on women from phytoestrogen effect. But yeah, just really go after that high-quality protein intake. And you could look at super foods, too. Like spirulina, it’s a really good source of iron and protein. So you’re like, “Oh, okay, I’ll add that in.”

And then if you’re more omnivorous, I guess, so you’re eating plants and animals then yeah, don’t be afraid to eat lean beef. Don’t be afraid to eat wild-caught fish. So yeah, just make sure that it’s high-quality.

Dr. Kara Fitzgerald: So you can achieve those numbers, those pretty high numbers, 1.7 and 2.4, grams per kilogram, using plant-based sources without a problem.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: Awesome.

Dr. Stacy Sims: Yep. Absolutely. I mean full disclosure, I’ve been vegan since I was 14. And so I did my whole race career and everything through it. I do supplement with whey protein isolate when I’m traveling because it’s really hard when you’re in airports and stuff to find good, quality vegan food. But it’s totally possible. I mean you look, it’s like you have your seeds and your nuts and your oatmeals and your sprouted grain breads. Plus your quinoa and your buckwheat and all those things, they all have protein in it.

Dr. Kara Fitzgerald: Fabulous, that’s great news. That’s great news. I mean I’m an omnivore but certainly plenty of people who are really leaning heavily in plant-based are interested in this and should have this available. So good news. That’s good news that you’ve been doing it and you function as an elite athlete following a vegan protocol.

What else do I want to ask you? I have a couple questions. So we want to be eating … We want to bathe our body in amino acids like post-event, before we go and work out, and then after. So we’re not working out in a fasted state. So when are we taking our protein? Do we ease up on protein when we’re not in an intense day, a demanding resistance training day? So there’s that question. How … We drop it down a little bit. And then the whole fasting piece. The fasting, as you know, it’s really popular right now and people are doing some pretty restrictive structures. We generally in our practice do more gentle interventions. Maybe 12 on, 12 off which I think is-

Dr. Stacy Sims: Which is normal.

Dr. Kara Fitzgerald: Which is normal.

Dr. Stacy Sims: Yeah.

Dr. Kara Fitzgerald: Amazing.

Dr. Stacy Sims: Yeah, normal eating.

Dr. Kara Fitzgerald: So what are your thoughts? A handful of questions there to you.

Dr. Stacy Sims: Yeah. Okay. So I’ll start with the fasting part and then we’ll get into the protein part. So with fasting, if we’re looking specifically at the hypothalamus. And when we’re talking about the hypothalamus in the brain, it’s where the energy-sensing neurons are. So it’s appetite control, it’s endocrine function. And specifically, we look at the KiSS-1 gene, kisspeptin. And when women do fasted training or they stay in a breakdown state post-exercise by not eating, it downturns our kisspeptin neurons. So what that does is it skews our appetite hormones. It also stimulates some thyroid disfunction. And it also stops luteinizing hormone pulse after a few weeks because the brain is like, “Hey, wait, there’s not enough nutrition coming in to support all of my functions, let alone if I were to get pregnant.”

So when we look at perimenopause, you’re still having some ovarian function and you’re having a skew of hormones but you’re still having that sensitivity plus you’re in this tired but wired, increased sympathetic state. So if you’re going to exercise in a fasted state, you’re driving cortisol up. And if we’re driving cortisol up, that again stimulates that sympathetic drive in a breakdown state. But it’s not breakdown of fatty acids, it’s the breakdown of lean mass. Because the first thing that goes when your body is under a starvation threat is lean mass because it’s highly energetic, but it also has a whole bunch of building blocks in it that the body’s going to take and use in other places.

So it is an appetite control and it’s a body composition thing and we know from research that having a little bit of food onboard before we do any kind of training amplifies that adaptation response. And also keeps the body in check so it doesn’t stay in a catabolic state which is that breakdown of lean mass.

To put it in simpler terms, if we’re looking at thresholds of calorie intake before we start seeing a lot of dysfunction. For women, we sit around 30 calories per kilogram of fat free mass. But for men, it’s 15. So men can get away with so much less before they get perturbance. This is why we see a lot of the fasting exercise literature and fasting literature being so robust because it’s all been done in men. There have been a few fasting studies done post-menopausal women but it’s been in sedentary, obese, post-menopausal women. And yes, they have lost body fat, but so does calorie restriction.

And there’s a really, really cool article in Nature that came out about a month ago that was looking at circadian rhythm and really investigating … I think it was like 300 people between the ages of 25 and 60, both men and women, and looking at when they ate. And for those people who didn’t eat until noon and then they stopped eating at six or seven at night, which is a typical eating window, they had a feedback mechanism that made them store more fat. Whereas people who ate earlier on in the day didn’t have that same response. So they were able to lose weight with some calorie restriction depending on the time of that calorie restriction. So when they’re looking at how do we maximize health and weight loss, it’s eating when the body needs it which is during the day. And not eating at night when the body is in its big reparation and sleep phase. So we see all of these different patterns of 20 and 4, 20 hours of not eating, 4-hour window to eat. What are you eating in that window, right?

Dr. Kara Fitzgerald: I know, right?

Dr. Stacy Sims: Right?

Dr. Kara Fitzgerald: Right.

Dr. Stacy Sims: And it’s not about putting in as many calories. It’s the quality and it’s the timing, right?

Dr. Kara Fitzgerald: Yes.

Dr. Stacy Sims: And we need to be able to fuel our bodies when it’s under stress. And there’s a lot of literature now coming out showing that if you’re looking to lose weight, a slight calorie restriction in the evening is so much better than doing this fasted stuff. You’re still going to get telomere length change if you’re not eating and having that 12 and 12, like you say, which is normal eating. So you’re not eating after dinner and then you have breakfast. You have all those changes that happen overnight which is normal, and that’s what we’re after. But we’ve gotten so far removed about what is normal eating, what are calories available, that people need to be retaught how to eat.

Dr. Kara Fitzgerald: Right, right, right. Well and especially it sounds like women because-

Dr. Stacy Sims: Especially.

Dr. Kara Fitzgerald: … we are … A lot of us are engaging in pretty restrictive fasting structures these days. You know in time-restricted eating or just plain fasting, full fasting.

Dr. Stacy Sims: Yeah. And there’s been some really cool stuff coming out looking at the timing for women versus nutrient timing for men. So nutrient timing for women is uber important because of hormone and appetite control. And if we delay eating after exercise and we stay in this breakdown catabolic state that occurs from exercise, then the hypothalamus is perceiving that as low energy availability. So it starts to have that whole metabolic downturn, appetite suppression, and misstep in our appetite hormones. We see sleep disturbances, and a lot of things that can lead to relative energy deficiencies even if you’re not an elite athlete. I mean we see this in 50 percent of our recreational female athletes. So that’s someone who goes to the gym three times a week, right? And they’re not super intensive. But for men, we’re not seeing it the same. So we really need to push the message that fasting is not good for women. We need to fuel for the activity that we’re doing, slight caloric restrictions, so don’t eat after dinner. Don’t have a midnight snack and then have breakfast.

Dr. Kara Fitzgerald: Awesome. And we want to, before we go and work out, we want to have a little protein onboard. We want to have some nutrition on board.

Dr. Stacy Sims: Yeah so it’s-

Dr. Kara Fitzgerald: And then post-

Dr. Stacy Sims: If we’re going to get up and do a resistance training workout, you can have around 90 calories or 20 grams of protein before. You don’t have to worry so much about carbohydrates. And then have your real meal afterwards. If you’re going to do a cardiovascular session, then you add only 30 grams of carbohydrate to that. So I mean I’m always talking on podcasts and interviews and stuff that my go-to in the morning before I go to an early session is a protein-fortified coffee. Where I have a double espresso cold brew from the night before. I put in some vanilla almond milk, some protein, some Schisandra. So I’m getting some carbohydrate, I’m getting some protein, I’m getting, oh, wake up. And then I go do my session, come back, and have breakfast. And it’s not a lot and it’s maybe 120 calories. But it doesn’t sit heavy, it gives my body what it needs, it stimulates the hypothalamus to say, “Hey, there’s some nutrition coming on.” It’s not like getting up two hours before your workout to have a full meal. It’s just something very small.

Dr. Kara Fitzgerald: And is it better to have a more bioavailable protein source pre-event than-

Dr. Stacy Sims: A fast, yeah.

Dr. Kara Fitzgerald: … just like a piece of chicken?

Dr. Stacy Sims: You could but egg whites. You could have some yogurt if you want. So it doesn’t have to be something, again, something super heavy.

Dr. Kara Fitzgerald: Good. All right. What else do I want to talk to you about? I think we’re really at our end here but it’s just been a great conversation. Just so interesting, so provocative, so important, really revolutionary. Because we have, we’ve been looking at men’s literature or science conducted in men. Talk to me about just some of the other lifestyle pieces. We don’t have the time to go in-depth but sleep, meditation, or some kind of a stress management protocol. Just some of the other, way up there, important things that we want to be doing as women.

Dr. Stacy Sims: Yes. Sleep is really important. And we see so many sleep disturbances in women. And a lot of it, again, is hormone and stress-driven. So to coin Andrew Huberman, non-sleep deep rest. So also yoga nidra, it’s a way of meditation, right?

Dr. Kara Fitzgerald: Right.

Dr. Stacy Sims: So these are really good ways of finding ways to activate our parasympathetic response. If we can activate parasympathetic, it doesn’t have to be right before bed but different periods throughout the day then it feeds forward to a better sleep through the night. We get better slow wave sleep, we get more REM sleep, even if it’s a short duration. So it’s really important to take those 10 minutes of breath. So it could be, “I’m really stressed out, I just need to get outside for 10 minutes and I’m going to just focus on what the breeze feels like on my face.” And just taking that deep breath in, exhale, and really just settling in the moment. And I sound very Yogi when I do that but I’m not Yogi. I’m just talking about how we just need to reset so that we have that moment of calm which helps downgrade that sympathetic drive that so many women are under all the time.

And then we can learn to tap back into that. So if we’re going to bed and we can’t sleep, we wake up in the middle of the night and we’re like, “Ah, I can’t get back to sleep.” You focus back on that 10 minutes of what does that breeze feel like? How did my skin feel? And it just brings you back to that moment which then triggers your body to get back into that parasympathetic.

Dr. Kara Fitzgerald: Which ultimately, at the beginning of our conversation discussing muscle mass, et cetera, is going to help preserve it and-

Dr. Stacy Sims: Exactly.

Dr. Kara Fitzgerald: Yeah. It’s like a real good feed-forward cycle. Well Dr. Sims, I just want to thank you so much for making time for us today and just moving through this really important science. It’s going to generate a ton of conversation, I think, for-

Dr. Stacy Sims: Excellent.

Dr. Kara Fitzgerald: … our platform. And yeah. And we’ll come back. We’ll have this conversation … We’ll have a part two when our kids start getting a little bigger. That would be great.

Dr. Stacy Sims: Yeah. We start talking about puberty then when our kids are bigger. Perfect.

Dr. Kara Fitzgerald: Thanks so much.

Dr. Stacy Sims: Thanks.

Dr. Kara Fitzgerald:  As always, thank you for listening to New Frontiers in Functional Medicine, where our sponsors help bring the very best minds in functional medicine, and today is no exception. Not everyone can be a sponsor on my platform, and I so appreciate the good work, relentless research, and generous support from my friends at Rupa Health, Biotics and Integrative Therapeutics. These are brands I know and trust in my own clinic and can confidently recommend to you. Visit them at RupaHealth.com, BioticsResearch.com and IntregrativePro.com, and please, tell them you learned about them on New Frontiers.

If it’s not too much to ask, I would appreciate a thumbs up and a kind review wherever you listen to New Frontiers. Thanks.

STACY T. SIMS, MSC, PHD, is a forward-thinking international exercise physiologist and nutrition scientist who aims to revolutionize exercise nutrition and performance for women. She has directed research programs at Stanford, AUT University, and the University of Waikato, focusing on female athlete health and performance and pushing the dogma to improve research on all women.

With the unique opportunities, Silicon Valley has to offer, during her tenure at Stanford, she had the opportunity to translate earlier research into consumer products and a science-based layperson’s book (ROAR) written to explain sex differences in training and nutrition across the lifespan. Both the consumer products and the book challenged the existing dogma for women in exercise, nutrition, and health. This paradigm shift is the focus of her famous “Women Are Not Small Men” TEDx talk. Her contributions to the international research environment and the sports nutrition industry has established a new niche in sports nutrition; and established her reputation as the expert in sex differences in training, nutrition, and health. As a direct result, she has been named:

• One of the top 50 visionaries of the running industry (2015) by DMSE Sports.
• One of the top 40 women changing the paradigm of her field (2017) by Outside Magazine.
• One of the top four visionaries in the outdoor sports industry (2017) by Outside Magazine – Genius Issue (no electronic version but here is the proof).
• One of the top four individuals changing the landscape in triathlon nutrition (2017) by Triathlete Magazine

Dr. Sims has published over 70 peer-reviewed papers, several books and is a regularly featured speaker at professional and academic conferences, including those by USOC and USA Cycling. Stacy currently holds a Senior Research Associate position with SPRINZ- AUT University, supervises PhD students, writes academic papers, and is on the advisory board of some cutting edge companies including Tonal Strength Institute, WILD.AI, and EXOS.  She also has her own business (www.drstacysims.com) where she creates and delivers online learning material focused on women training with their physiology across the lifespan.

Dr. Stacy Sims website

Dr. Sims research papers

Women are Not Small Men TEDs talk

Paper: The role of insufficient sleep and circadian misalignment in obesity

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