Dr Stacy Sims Female Specific Exercise Nutrition For Health Performance Longevity

High-Level Overview

Andrew Huberman talks with Dr. Stacy Sims, an exercise physiologist and nutrition scientist who specializes in training and nutrition for women, about where women's needs differ from men's and where they don't. The conversation starts with a question Huberman gets constantly, whether intermittent fasting and fasted training work the same way for women, and grows into a full guide: what to eat before and after training, how to structure resistance and cardiovascular work at different ages, why perimenopause is a turning point, how the menstrual cycle and oral contraceptives affect training, iron and blood testing, caffeine and adaptogens, cold versus heat exposure, sleep, supplements, pregnancy and a longevity plan for women over 50.

The tone is brisk, practical and often myth-busting. Sims speaks from research and from her work with elite and tactical athletes, and repeatedly challenges popular advice that she says is based on male data or on aesthetics rather than physiology. Huberman adds neuroscience context and presses for concrete protocols. The conversation moves steadily from mechanisms to specific, usable protocols, with a few detours into history and culture.

The Discussion Explores:

• Why intermittent fasting and fasted training tend to backfire for active women, via cortisol and kisspeptin neurons
• Small pre-training fuel and a tighter post-training protein window for women
• Resistance training by age: to failure when younger, heavy with reps in reserve as women get older
• Perimenopause as a sharp aging point, and why polarized training beats moderate-intensity classes
• Tracking the menstrual cycle individually, the 10-minute rule, and fueling in the luteal phase
• Oral contraceptives, IUDs, PCOS, iron and when to get blood work
• Caffeine, schisandra, milder cold exposure, sauna for hot flashes, and a post-training sauna protocol
• Sleep, supplements, pregnancy, and a longevity plan built on jumping, lifting, sprints and protein

Deep Dive into Main Ideas

Fasting and Fasted Training Work Differently for Women

Sims separates intermittent fasting, such as holding a fast until noon or longer, from time-restricted eating, which she calls a fancy way of describing normal eating in line with the circadian rhythm. For active women, she says, the former is very detrimental unless there is PCOS or another metabolic condition. One reason is that "we as women have more oxidative fibers," which makes women already more metabolically flexible than men, so the flexibility benefits often cited for fasting matter less. Exercising without fuel raises cortisol, and without fuel women can't reach intensities high enough to trigger the post-exercise growth hormone and testosterone responses that bring cortisol back down.

The second reason is the brain. Sims explains that men have one area of kisspeptin neurons while women have two, one tied to appetite and luteinizing hormone and the other to estrogen and thyroid. Starting the day under stress without fuel perturbs and downregulates these neurons, and she says that after four days there is thyroid dysregulation and a change in luteinizing hormone pulse. She also cites population research suggesting that people who fast until noon and eat until 6 p.m. have worse outcomes related to obesity than those who eat around 8 a.m. and finish by 4 or 5 p.m. Because cortisol peaks about half an hour after waking, women who don't eat stay more sympathetically driven, feeling tired but wired. Huberman admits his own routine of hydration and caffeine, training fasted and eating at 11 a.m. is probably the worst approach for the women who adopted it with him. Sims adds that it gets worse in perimenopause, when baseline cortisol rises and unfueled women drift into moderate intensity and lose about 2 to 5 percent of their top lifting load.

What to Eat Before and After Training

The fix is small. Sims herself has a double espresso with sweetened almond milk and a scoop of protein powder before an ocean swim, and just the protein in coffee before the gym. Citing work by Abbie Smith-Ryan at UNC, she says a strength session needs only around 15 grams of protein beforehand, which also raises post-exercise oxygen consumption, and cardio up to an hour adds about 30 grams of carbohydrate. If someone wants a real meal, about half an hour before is fine. The goal is to raise blood sugar enough to signal the hypothalamus that nutrition is on board, then have a real breakfast within 45 minutes after. She notes that the longer women withhold food after exercise, the more the brain senses low energy, and the first thing lost is lean mass, which is very hard for women to build. Both she and Huberman criticize calorie math like two cookies equals 30 minutes on a treadmill, with Huberman noting how calorie counting can drift toward eating disorders.

After training, Sims recommends around 35 grams of high-quality, leucine-rich protein within 45 minutes for women in their reproductive years and 40 to 60 grams from perimenopause onward, because the body becomes more anabolically resistant with age. She argues the idea that there is no recovery window is based on male data: "Women it's within 60 minutes and for men it's up to three hours" for metabolism to return to baseline. For carbohydrate, she suggests about 0.3 grams per kilogram within two hours, noting men need it more because they burn through liver and muscle glycogen faster. She frames low energy availability with a number: the tipping point for endocrine dysfunction is 15 calories per kilogram of fat-free mass for men and 30 for women.

Resistance Training Across the Ages

Sims explains reps in reserve and rating of perceived exertion: an 8 out of 10 means finishing a set with two good reps left. For women aged about 20 to 30 she focuses first on learning to move well, then three to four resistance sessions a week of 45 to 60 minutes, with up to two high-intensity sessions or a sprint finisher. In the 30s, the emphasis shifts to compound lifts and periodized six-week blocks, building a base for power training later. A woman in her 40s who has never lifted should spend two weeks to four months learning movement, because soft tissue injuries rise with changing estrogen, then aim for at least three compound-lift sessions plus sprint or high-intensity work. Her summary: "The key when you're younger is working to failure. The key when you're older is working heavy." Heavy work with reps in reserve creates a strong central nervous system response, which she links to strength, proprioception and slowing cognitive decline.

She explains why women's strength rises quickly when they start lifting. Many women grew up steered toward cardio and have never exposed their nervous system to that stress, so neural adaptations come fast, while muscle bulk builds slowly. Huberman adds that the pump during a session offers a temporary preview of what hypertrophy might look like. For beginners without a trainer, Sims suggests bodyweight moves or a backpack loaded with cans at home, Kelly Starrett's mobility work, online programs with video feedback, machines at gyms like Planet Fitness, and kettlebells. Huberman stresses adjusting seat height and pins on machines rather than rushing.

Perimenopause and Polarized Training

Sims says men age more linearly, while women hit a definitive point in their late 40s and early 50s with falling and flattening sex hormones, more cycles without ovulation, weight gain, poor sleep and soft tissue problems such as frozen shoulder and plantar fasciitis. Her answer is polarized training: heavy lifting and true high-intensity work on one end, very easy recovery like walking on the other, and very little in between. She is openly critical of Orangetheory and F45 for marketing to this age group, since those classes leave women feeling smashed but in moderate intensity, which raises cortisol without triggering the hormonal responses that lower it. As she puts it, "It's like well actually they shouldn't do moderate intensity."

True high-intensity intervals are one to four minutes at 80 percent or more, like 400 or 800 meter repeats with variable recovery, or a gym circuit done every minute on the minute. Sprint intervals are 30 seconds or less all out, followed by two or three minutes of recovery, a couple of times a week. One example she gives women: a 20-minute heavy lower-body set, then all-out 30-second efforts on an assault bike, where most are spent after two. She is honest that she still enjoys long gravel rides for her mental health, but says zone 2 is not what drives body composition and longevity. Later she explains the mechanism: hard efforts create epigenetic changes that increase GLUT4 transporters for glucose uptake and train the body to resolve inflammation, a role estrogen used to play, which helps counter the rise in visceral fat from the mid-40s onward.

Training With the Menstrual Cycle

Sims says recent meta-analyses concluding the cycle has no effect rely on small groups of college-aged women with regular cycles. In general, the low-hormone phase from the first day of bleeding to ovulation handles physical and mental stress best and is a good time to chase a personal record. The luteal phase brings a pro-inflammatory immune response, harder access to carbohydrate, higher sympathetic drive and a body focused on building the uterine lining, so women should eat more carbohydrate and protein in the week before their period. But not every woman ovulates each cycle; she says most have four to five anovulatory cycles a year, so tracking one's own patterns matters more than generalizations. She cautions that heart rate variability drops with progesterone and signals ovulation but not readiness.

Her practical tool is the 10-minute rule: if you wake up feeling awful, "Give yourself 10 minutes." If you still can't hit your intensities, switch to recovery work, and don't worry if that happens three days in a row. She traces the myth that hard training disrupts periods to a sporting culture where losing one's period meant being more like the men. The real cause, she says, is underfueling: "It's the act of not fueling appropriately for it." A small deficit of 150 to 200 calories away from training is fine; the goal is that "you train hard, you eat well and your body responds in kind." She also notes that the estrogen surge before ovulation blunts appetite and progesterone drives cravings later, so women may need to eat even when not hungry.

Birth Control, PCOS, Iron and Blood Tests

Sims recounts that the pill was funded by Katharine McCormick and Margaret Sanger, and that the placebo week was designed so women would still have a bleed, but it is a withdrawal bleed, not a period. The pill downregulates ovarian function and, in active women, raises inflammatory and oxidative responses. Effects vary by progestin generation and estrogen dose; for example, she says a 30 microgram estrogen dose increases hypertrophy but not strength, which can be a problem for Olympic lifters. She mentions a 2024 study showing reversible amygdala changes with oral contraceptive use in adults, linked to more fear and less risk taking, with unknown effects in developing girls, and she criticizes doctors who hand out the pill for irregular cycles or skin. Many of her tactical athletes use a hormonal IUD instead, since it doesn't have systemic effects on adaptation or mood.

She describes menstrual fluid as a promising diagnostic sample for HPV, PCOS and endometriosis. PCOS appears more common, partly due to better detection and partly to rebound after stopping the pill or eating more after low energy availability, and it is common in Olympic athletes. For women worried about low ferritin, she suggests iron every other day for ten days starting on the first day of bleeding, when absorption is best, and aiming for around 50 rather than accepting 20 to 25 as normal. For blood work at one point in the cycle, she recommends five to seven days before the next period, adding day two of bleeding for a second test.

Caffeine, Adaptogens, Cold and Heat

Sims says caffeine tolerance is more genetic than sex-based, but in perimenopause women become more sensitive to caffeine-related blood sugar swings and may feel hypoglycemic mid-workout, so they should eat with it. She is a fan of schisandra, an adaptogen she puts in her morning coffee and uses in the afternoon instead of more caffeine, saying it gives focus without interfering with sleep. Huberman shares his experience that nicotine gum is habit-forming and bad for skin.

On cold, she prefers heat for women. She says ice baths are too cold for women, while water around 16 degrees Celsius, roughly 55 to 56 Fahrenheit, is enough to get the benefits without severe constriction. In a pilot study with athletes with severe endometriosis, cold exposure starting around ovulation and continued for ten days across three cycles reduced symptoms. Huberman stresses never combining hyperventilation, breath holds and water. Sims recommends a traditional Finnish sauna rather than infrared, saying it improves insulin and glucose control, heat shock proteins and cardiovascular responses, and reduces hot flashes by strengthening the signal to the hypothalamus. Her post-training protocol, which Huberman dubs the Sims protocol, is up to 30 minutes of sauna after a lifting or cardio session, followed by slow rehydration, which extends the training stimulus and increases red blood cells and plasma volume, similar to altitude. She also describes a pre-sprint "track stack" of 200 milligrams of caffeine, a baby aspirin and beta-alanine, used only for hard sessions with good recovery.

Sleep, Supplements and Pregnancy

Sims says slow-wave sleep drops and sleep latency rises in roughly the ten days before a period, when mood issues also increase, so sleep hygiene matters most then. She mentions theanine and apigenin, rhodiola with theanine, a cool room, and non-sleep deep rest or yoga nidra, and says perimenopausal insomnia with hot flashes may call for a sleep specialist. On supplements, "the number one is creatine": three to five grams of creatine monohydrate daily for brain, mood and gut health, preferably Creapure, which she says causes fewer stomach side effects. She says creatine doesn't cause hair loss, attributing midlife complaints to progesterone changes. Next is vitamin D3 at about 2,000 to 5,000 IU depending on sun, which also helps with iron, then quality protein powder and adaptogens such as ashwagandha, tulsi, lion's mane and reishi, with calming ones taken around 4 p.m.

On pregnancy, she says "your body tells you what you can do": anaerobic capacity drops protectively, and the goal becomes maintaining, not gaining. The worst case is a very active woman stopping everything out of fear. She is cautious about cold in pregnancy but says hot yoga around 40 degrees Celsius is not harmful if a woman leaves or lies down when too hot, since mild stress can improve placental blood vessels.

A Longevity Plan for Women Over 50, and Diet

For women over 50, Sims wants to shift the goal to living independently at 80 or 90 with good balance, bones and strength. Her big pieces are jump training for 10 minutes three times a week, true impact rather than soft landings, which a colleague's research showed can move women from osteopenic to normal bone density in four months; heavy resistance training; sprint intervals; and protein of about 1 to 1.1 grams per pound, or 2 to 2.3 grams per kilogram. She notes women can lose about a third of their bone mass around menopause without an intervention. For women 20 to 40, she emphasizes fun, heavy resistance training and some high-intensity work so the brain is exposed to lactate, which she links to protection against cognitive decline.

On food, she prefers rice, oatmeal, good sourdough, sweet potatoes, quinoa and colorful fruit and vegetables for a diverse gut microbiome that helps with hormone metabolism, allowing processed treats only after training. She follows the 80/20 rule, "80% of the time you're spot on 20% is life." A vegan since high school, she still says most fats should come from whole plant foods but that fear of saturated fat from dairy is outdated. Her magic-wand wish is for women to relearn how to listen to their bodies, since she says women have forgotten what it means to listen to themselves in their bodies.

Conclusion

Dr. Stacy Sims's message is that women aren't small men and shouldn't train or eat as if they were. Most popular advice, from fasted workouts to the idea that there's no post-exercise window, comes from male data. Women do better when they fuel before training, get protein soon after, lift heavy as they age, and replace moderate-intensity grinding with a mix of true sprints and easy recovery. The menstrual cycle, perimenopause and contraception all shape the picture, but her answer is consistent: track your own patterns, eat enough, and use smart stresses like heavy lifting, jump training and sauna to build a body that stays strong and independent for decades. It is a dense, practical episode for any woman, or anyone coaching women, who wants to train with her physiology rather than against it.

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