Women’s Exercise & Nutrition for Health, Performance and Longevity: What Does the Science Say?

What if much of the exercise and nutrition advice women have followed for years was never designed specifically for them?

In a conversation attracting more than 2.4 million views, exercise physiologist Dr Stacy Sims joins neuroscientist Dr Andrew Huberman to challenge conventional thinking about women's health, performance and longevity. Their discussion raises important questions about how women can train, eat and stay healthier throughout life.

What the News Is Saying

On 22 July 2024, neuroscientist Dr Andrew Huberman released a YouTube interview entitled Female-Specific Exercise & Nutrition for Health, Performance & Longevity, featuring exercise physiologist and nutrition scientist Dr Stacy Sims. By 6 October 2026, it had attracted approximately 2.4 million views and 2,796 comments.

Dr Sims challenges familiar approaches to women's fitness, discussing fasting, exercise fuelling, strength training, hormones, high-intensity workouts, sleep and nutrition for longevity. The conversation begins with a particularly provocative question: Are women helping or hindering their performance by exercising without eating first?

We will follow the interview's practical recommendations, explain the science behind them and explore what women can use in their own exercise and nutrition routines.

Should Women Exercise on an Empty Stomach?

Exercising before breakfast has become a popular habit, particularly among people hoping to burn more fat. But is fasted training really the best approach for women?

Dr Stacy Sims argues that exercising without food can increase physiological stress, particularly when women are already dealing with demanding workouts or hormonal changes. She highlights cortisol, a hormone involved in the body's stress response, and explains why eating before training may help women perform at the intensity they want.

Her advice is practical: fuel the exercise you intend to do. That does not necessarily mean eating a large breakfast. In the interview, she describes incorporating a small amount of protein and carbohydrate before an early workout, followed by adequate nutrition afterwards to support recovery.

One important distinction deserves attention. Burning more fat during an individual fasted workout is not the same as losing more body fat over time. Research into exercise and nutrition considers overall energy intake, training performance and recovery—not simply whether breakfast comes before or after exercise.

For women interested in strength, performance and longevity, the useful question may be less about exercising on an empty stomach and more about eating well enough to get the most from their training.

Strength Training: Why It Matters for Women's Longevity

For years, many women have been encouraged to focus on cardio, calorie burning and lighter weights. But Dr Stacy Sims argues that building and maintaining muscle should be a central priority for women's health, performance and longevity.

Her message is striking: women should not be afraid to lift heavy weights. Challenging resistance training helps develop strength and supports the muscles and bones that become increasingly important as we age.

Muscle is more than something that makes us look toned. It plays an important role in movement, balance, glucose regulation and everyday independence. Maintaining muscle strength can help women remain active and capable for longer.

Dr Sims also discusses the value of progressive overload—gradually increasing the challenge as strength improves. This might involve heavier weights, more repetitions or more demanding exercises, depending on individual ability and experience.

And what about cardio? Strength training and cardiovascular exercise serve different but complementary purposes. Walking, cycling, swimming and other aerobic activities support cardiovascular fitness, while resistance training develops strength and helps preserve muscle.

The practical message is simple: train to become stronger, not merely to burn calories. A balanced routine that develops both muscular strength and cardiovascular fitness offers a powerful foundation for healthy ageing.

How Women's Hormones Affect Exercise and Nutrition

Why can the same workout feel easy one week and exhausting the next? Dr Stacy Sims argues that women's hormonal changes can influence how they experience exercise, recovery, appetite and nutrition.

During the menstrual cycle, oestrogen and progesterone fluctuate. Dr Sims discusses how these changes may influence energy, motivation and the ability to handle demanding workouts. But she emphasises an important practical point: not every woman responds to her menstrual cycle in the same way.

Her suggestion is to track your own patterns rather than follow a rigid training calendar. Noticing changes in energy, sleep, appetite and workout performance can help women recognise when they feel ready to push harder or need more recovery.

Nutrition matters too. Dr Sims highlights how appetite can change across the menstrual cycle, sometimes making it harder to eat enough around demanding workouts. Training hard and eating well belong together. Adequate fuelling helps support performance and recovery.

What about perimenopause and menopause? Falling and fluctuating hormone levels can coincide with changes in sleep, body composition and exercise recovery. Dr Sims particularly emphasises resistance training, high-intensity exercise and adequate nutrition during these transitions.

The practical message: understand your body, recognise your patterns and adapt your training and nutrition to your needs. Women do not all need the same programme simply because they are the same age or at the same life stage.

Hormonal Contraception and Exercise: What Does Dr Stacy Sims Say About the Pill?

Can taking the contraceptive pill affect a woman's strength, athletic performance, mood or menstrual cycle?

Dr Stacy Sims argues that hormonal contraception can affect more than reproduction, but she also emphasises that different contraceptives contain different hormones and cannot all be treated alike.

Why the bleeding experienced on the pill is different

Dr Sims begins with the history of oral contraception, including the involvement of Katharine McCormick and Margaret Sanger in its development.

She explains why many combined oral contraceptive regimens traditionally included three weeks of active tablets followed by a week without active hormones.

The bleeding during that hormone-free interval is withdrawal bleeding, not the same process as menstruation following a natural ovulatory cycle.

Combined oral contraceptives generally suppress ovulation, altering the hormonal pattern that would otherwise occur across the menstrual cycle.

For Dr Sims, this matters when researchers compare exercise performance among women using hormonal contraception and women with natural menstrual cycles.

Does the contraceptive pill affect athletic performance?

Dr Sims discusses research into inflammatory responses, oxidative stress and changes in muscle adaptation among women taking oral contraceptives.

But she makes an important distinction: there isn't enough research to establish one universal effect on exercise performance.

She discusses different generations of progestins and different oestrogen doses.

Among her examples:

• She describes preliminary research suggesting that particular progestin formulations may influence speed and power.
• She discusses a 30-microgram oestrogen formulation associated with changes in muscle hypertrophy without equivalent improvements in strength.
• She explains why even relatively small changes in performance matter to elite power athletes and Olympic weightlifters.

She also discusses situations in which athletes and their clinicians have considered changing contraceptive formulations because of performance-related concerns.

Her central point is that the effects depend on the hormonal formulation and the individual woman.

These specific performance claims need to be checked against the underlying studies before publication.

What about mood, fear and the brain?

Dr Sims raises research published in 2024 examining oral contraceptive use and the amygdala, a brain structure involved in emotional processing and threat detection.

She argues that hormonal contraception may influence responses to stressful or threatening situations.

She is particularly concerned about what remains unknown for adolescents whose brains are still developing.

Her concern is that the broader neurological effects of hormonal contraception deserve more research, not simply its effectiveness at preventing pregnancy.

Her interpretation of the research should not be taken to mean that contraceptive pills have been proven to cause persistent fear, personality changes or lasting brain damage.

What if an athlete has irregular periods?

Dr Sims questions the practice of prescribing hormonal contraception solely to conceal an unexplained menstrual problem.

She argues that if a young athlete has irregular or absent periods, doctors should investigate potential causes, including insufficient energy intake and demanding training.

Suppressing or regulating bleeding does not necessarily resolve the underlying issue.

Her message is to investigate why a menstrual problem exists rather than assuming that a predictable bleeding pattern proves hormonal health.

Are IUDs different?

Dr Sims distinguishes oral contraceptives from intrauterine devices.

She discusses both copper IUDs and hormonal IUDs such as Mirena.

According to Dr Sims, these are frequently used by athletes because they provide long-lasting contraception without requiring daily tablets.

She describes important differences:

Hormonal IUDs: These can reduce menstrual bleeding by thinning the uterine lining.

Copper IUDs: These do not release contraceptive hormones, but heavier bleeding can occur, particularly during the initial months.

Dr Sims suggests that IUDs may have fewer systemic effects on athletic adaptation than oral contraceptives.

However, hormonal IUDs can still have systemic effects, and individual experiences vary.

What about contraceptive injections and bone density?

Dr Sims separately raises depot contraceptive injections, such as Depo-Provera.

She expresses concern about bone mineral density loss associated with prolonged use, particularly among younger athletes.

Her concern is relevant because adolescence and young adulthood are important periods for developing peak bone mass.

The takeaway from Dr Sims' discussion: Hormonal contraception is not one uniform intervention. Its formulation, intended purpose, potential side effects and individual response all matter.

Could Menstrual Blood Help Diagnose Women's Health Problems?

What if menstrual fluid, usually discarded, could provide valuable information about hormone-related disorders?

Dr Stacy Sims discusses an emerging area of research: using menstrual blood and tissue as a potential source of diagnostic information.

Why researchers are studying menstrual fluid

Dr Sims explains that menstrual fluid contains more than blood.

It also includes cells and material shed from the uterine lining, along with proteins and inflammatory signalling molecules called cytokines.

Researchers are investigating whether analysing this material could reveal information about reproductive health.

She identifies potential applications involving:

• Human papillomavirus (HPV).
• Polycystic ovary syndrome (PCOS).
• Endometriosis.
• Hormonal and endometrial changes.

Her argument is that a regularly available biological sample could offer insights that are difficult to obtain through conventional testing.

However, identifying promising biomarkers is not the same as having a clinically validated diagnostic test. The accuracy and usefulness of specific menstrual-fluid tests must be established separately.

Menstrual-fluid biomarkers are under investigation, particularly for endometriosis, but promising studies do not yet establish clinically validated screening or diagnostic tests for endometriosis, PCOS or HPV.

PCOS: why diagnosis can be complicated

Huberman asks Dr Sims about polycystic ovary syndrome, a condition frequently associated with elevated androgen levels and menstrual irregularities.

Dr Sims questions whether every apparent increase in PCOS reflects a genuine increase in the condition itself.

She discusses the possibility that improved detection contributes to greater recognition.

She also raises a more controversial explanation: some ovarian changes observed after stopping hormonal contraception may resemble features of PCOS without necessarily establishing the diagnosis.

Dr Sims refers to what she calls rebound PCOS, describing how ovarian activity can change after prolonged suppression of ovulation.

She also discusses athletes recovering from periods of low energy availability, where changes in food intake and reproductive function can alter ovarian activity.

These explanations are her interpretations and should not be treated as established diagnostic categories without supporting clinical evidence.

PCOS among female athletes

Dr Sims discusses the relationship between androgens and sporting performance.

She suggests that certain hormonal characteristics associated with PCOS might affect strength, recovery and athletic performance.

She refers to observations involving elite female athletes, including Olympic-level competitors.

Her point is that reproductive hormones, physical performance and metabolic health may be interconnected, but she does not establish that PCOS reliably provides an athletic advantage.

How intense training can affect reproductive hormones

The interview then turns to the hormonal effects of demanding training.

Dr Sims discusses changes in cortisol, testosterone, oestrogen and luteinising hormone during periods of physiological stress.

She explains that a particularly demanding training block can influence hormone signalling.

For female athletes, she describes monitoring hormonal patterns across preseason, competition and recovery periods.

Her concern is identifying excessive training stress before menstrual dysfunction develops.

This connects with her earlier warnings about under-fuelling, recovery and the importance of recognising menstrual-cycle changes.

Low Ferritin, Iron Supplements and Fatigue: What Does Dr Stacy Sims Recommend for Women?

Women lose blood during menstruation, but does that mean they should automatically take iron supplements?

Dr Stacy Sims says no. She argues that fatigue has many possible causes and that iron requirements should be assessed in context.

Why the timing of iron supplements may matter

Dr Sims discusses hepcidin, a hormone involved in regulating iron absorption and movement around the body.

She explains that hepcidin responds to inflammation and the body's iron status.

According to Dr Sims, changes across the menstrual cycle may influence how effectively supplemental iron is absorbed.

For women concerned about low ferritin, she describes a particular approach:

Taking iron every other day, beginning on the first day of menstrual bleeding and continuing over approximately ten days.

She argues that absorption may be more favourable during that part of the cycle, while hormonal and inflammatory changes after ovulation may reduce it.

This is Dr Sims' proposed supplementation schedule, not a universal clinical prescription.

Alternate-day oral iron dosing has supporting evidence in some clinical settings; the specific ten-day menstrual-cycle schedule described here is not an established treatment protocol for iron deficiency.

What ferritin level does she want to see in active women?

Ferritin is a protein used to assess the body's iron stores.

Dr Sims gives a specific example.

A physically active woman might receive a ferritin result of approximately 20–25 and be told that it falls within the laboratory reference range.

Dr Sims says she would prefer many active women to have ferritin levels closer to 50, rather than approximately 20–25. Ferritin is commonly reported in µg/L, but the interview's units should be confirmed before publication. Her preference is not a universal clinical target: results must be interpreted alongside symptoms, haemoglobin, inflammation and individual circumstances.

Her reasoning is that a result at the lower end of the reference interval may not be optimal for every athlete's circumstances.

She distinguishes between a laboratory result being within range and the possibility that low iron stores could still be relevant to symptoms or performance.

But a ferritin target cannot be prescribed from this interview alone. The clinical interpretation depends on the laboratory units and reference interval, symptoms, haemoglobin, inflammation and other findings.

Does fatigue always mean low iron?

Dr Sims is explicit that it does not.

Fatigue may have multiple causes, including inadequate fuelling, poor recovery, sleep problems and other health conditions.

Her warning is against automatically blaming iron deficiency every time a woman feels exhausted.

Iron deficiency itself should not be overlooked, particularly with heavy menstrual bleeding or other risk factors, but assessment matters.

Iron supplements should follow clinical assessment: excess iron can be harmful, and unexplained fatigue or heavy bleeding may need investigation.

When does she suggest testing reproductive hormones?

Huberman asks Dr Sims about timing blood tests when a woman can only afford one or two assessments during her menstrual cycle.

Dr Sims offers two specific suggestions.

First test: approximately five to seven days before the expected next period.

She describes this as a mid-luteal assessment, when progesterone and oestrogen patterns can provide information about the later part of the cycle.

Second test: day two of menstrual bleeding.

She suggests that this offers a useful early-cycle comparison, particularly for baseline oestrogen measurements.

Dr Sims considers the combination more informative than a single untimed hormone measurement.

The appropriate date depends on actual ovulation timing and the reason for testing. A fixed calendar day is not equally informative for every woman, especially where cycles are irregular.

For otherwise healthy women aged 45 or over, NICE advises that perimenopause can generally be identified from symptoms and menstrual history without routine hormone blood tests.

The practical message from this discussion: Interpret iron stores, fatigue and reproductive hormones in the context of the individual woman rather than relying solely on generic assumptions.

Caffeine, Cold Plunges, Saunas and Sleep: What Does Dr Stacy Sims Recommend for Women?

Should women be drinking coffee before training, jumping into ice baths or using a sauna to improve recovery? And why might sleep become more difficult during the menstrual cycle or perimenopause?

Dr Stacy Sims has some surprisingly specific answers — including why she prefers heat over extreme cold exposure for women.

Caffeine: why your usual pre-workout coffee might suddenly make you feel unwell

Dr Sims explains that caffeine sensitivity is influenced more by genetics than by sex alone. Some people metabolise caffeine quickly, while others respond much more slowly.

However, during perimenopause, women may become more sensitive to blood-sugar fluctuations associated with caffeine.

She describes a familiar situation: a woman drinks her usual double espresso before exercise, but halfway through her workout she becomes dizzy, lightheaded or nauseous.

According to Dr Sims, changes in insulin sensitivity and blood-sugar regulation during perimenopause may contribute to this reaction.

Her practical suggestion is to eat something with the coffee, rather than simply consuming more caffeine during the workout.

She also discusses schisandra, an adaptogenic plant that she personally adds to her morning coffee. She describes its potential usefulness for focus and mental fatigue, although these proposed effects need independent clinical assessment.

Cold plunges: Dr Sims says women don't need extremely icy water

Cold-water immersion has become popular for its supposed effects on alertness, mood and metabolism.

But Dr Sims argues that extreme ice baths may be unnecessarily cold for women, producing intense blood-vessel constriction and a strong stress response.

She suggests that water around 16°C (approximately 55–56°F) can still produce the alertness-related responses people seek from cold exposure, without requiring near-freezing temperatures.

She makes an exception for competitive open-water swimmers and triathletes, who may need specific cold-water acclimatisation to prepare for races.

Dr Sims also describes preliminary work investigating cold exposure around ovulation in athletes with endometriosis. She reports encouraging observations, but this should be understood as early research rather than an established treatment.

An important timing distinction: Andrew Huberman also explains that cold-water immersion immediately after resistance training may reduce some of the muscle-building adaptations. He suggests separating immersion from strength training by several hours, potentially avoiding it on the same day when muscle growth is the goal.

Water at 16°C is not universally safe: sudden cold-water immersion can affect breathing, heart rate and blood pressure. Evidence about preserving muscle growth by waiting several hours after resistance training remains insufficient.

Why Dr Sims prefers saunas for women

Dr Sims takes a different view of deliberate heat exposure.

She favours traditional Finnish-style saunas over infrared saunas, explaining that a traditional sauna produces stronger heating of the body's core rather than primarily warming the skin.

During the discussion, she refers to sauna temperatures around 60–80°C, while Huberman separately discusses hotter Finnish sauna ranges.

Dr Sims describes several possible physiological effects of heat exposure, including changes in cardiovascular function, heat-shock proteins, and insulin and glucose regulation.

But her most interesting argument concerns menopause.

Could a hot sauna actually help women who suffer from hot flushes?

It sounds contradictory. Yet Dr Sims argues that repeated heat exposure may help retrain the body's temperature-regulating responses.

She discusses the hypothalamus — a brain region involved in temperature control — and proposes that heat exposure could improve temperature regulation and reduce menopausal hot flushes and night sweats.

This is her proposed explanation, not proof that sauna treatment reliably reduces menopausal symptoms in clinical practice.

Her post-workout sauna protocol

Dr Sims also describes a specific approach for athletic performance.

After resistance training or cardiovascular exercise, she discusses entering a sauna for up to 30 minutes, but no longer.

Her explanation is that heat exposure extends the cardiovascular stimulus of exercise. She proposes that changes in fluid balance, plasma volume and red-blood-cell production could improve endurance adaptations, somewhat like training at altitude.

During the discussion, Huberman raises drinking water with some salt before entering the sauna, which Dr Sims agrees with.

An important safety distinction: This is a description of a performance protocol discussed in the interview, not a recommendation for everyone to follow it. Deliberately increasing dehydration and heat stress can be dangerous, particularly for people with cardiovascular conditions, low blood pressure, certain medications or poor heat tolerance. The proposed performance effects also require independent evidence review.

There is not yet established clinical evidence that sauna use treats menopausal hot flushes; the interview's heat exposures and durations are not validated treatment protocols, and heat can cause dehydration, dizziness or blood-pressure changes.

Why women may sleep differently during their menstrual cycle

Dr Sims' sleep discussion is much more specific than simply advising women to sleep well.

She says that during approximately the final ten days before menstruation, women may experience measurable changes in sleep architecture.

She describes three changes:

• Less slow-wave sleep: reduced time in the deepest stages of sleep.
• Longer sleep latency: taking more time to fall asleep.
• More light sleep: spending more time in less restorative stages.

Dr Sims associates these changes with hormonal fluctuations and the interaction between oestrogen and serotonin.

Her recommendation is to pay particular attention to the sleeping environment during this phase of the cycle.

She specifically mentions keeping the bedroom cool and comfortable, limiting screens, and considering individual temperature preferences, which may differ from those of a partner sharing the bed.

She also discusses L-theanine and apigenin as possible sleep-related supplements, although they should not automatically be assumed effective or suitable for everyone.

Perimenopause, night sweats and insomnia

Dr Sims explains that sleep can become substantially more disrupted during perimenopause.

Hot flushes and night sweats interfere with temperature regulation, while hormonal changes may influence the nervous system's ability to settle into a restful state.

She connects these changes to sleep quality, melatonin, serotonin and oestrogen's activity in the brain.

For women struggling with these symptoms, she suggests considering specialist sleep support, rather than treating persistent insomnia as something they simply have to tolerate.

She also discusses relaxation approaches such as yoga nidra and non-sleep deep rest, alongside a cool sleeping environment. She mentions rhodiola and L-theanine, but these supplement suggestions require separate safety and efficacy assessment.

What stands out from her interview is that women's sleep needs are not necessarily constant throughout life. Dr Sims argues that menstrual-cycle changes and the menopausal transition should be taken seriously when assessing sleep problems, training recovery and daily wellbeing.

Creatine for Women, Vitamin D, Protein Powder and Adaptogens: Dr Stacy Sims' Supplement Recommendations

Which supplements does Dr Stacy Sims consider most useful for women? Does creatine cause water retention or hair loss? And when should supplements such as ashwagandha or schisandra be taken?

Dr Sims gives several specific recommendations, while Andrew Huberman questions the evidence and possible side effects.

Creatine: Dr Sims' first choice

When asked which supplement she would prioritise for women, Dr Sims immediately chooses creatine.

She says women of different ages may benefit from it.

Beyond strength and exercise performance, she discusses emerging research into creatine's possible effects on brain function, mood and gut health.

Her suggested amount is 3–5 grams of creatine monohydrate daily.

Creatine's effects on cognition remain under investigation; encouraging findings for some outcomes do not establish an overall cognitive benefit or dementia prevention.

She also expresses a preference for the Creapure formulation, describing differences in manufacturing methods.

Dr Sims reports that some women experiencing digestive discomfort with other products have tolerated that formulation better.

This is her experience and preference; the claim that a particular manufacturing process reliably produces fewer side effects requires independent comparison.

Does creatine cause water retention?

Huberman raises a common concern: creatine can increase the amount of water stored within muscle tissue.

He explains that this can increase body weight without representing additional body fat.

But Dr Sims stresses that weight gain from water retention is not inevitable.

She says some women taking approximately 3 grams daily do not notice this effect.

The discussion distinguishes increased water stored within muscle from the idea that creatine necessarily causes generalised swelling.

What about creatine and hair loss?

Huberman then raises another widely discussed concern.

Some people have associated creatine supplementation with changes in dihydrotestosterone (DHT), a hormone involved in androgen-related hair loss.

He notes that this concern arose largely from limited indirect research.

Dr Sims argues that there is no convincing evidence establishing creatine as a cause of hair loss.

She also discusses hormonal changes during midlife, including progesterone fluctuations, as possible explanations when women notice changes in their hair.

The important distinction is that an association or concern does not establish causation. Neither does the absence of strong evidence prove that no individual could ever experience an adverse effect.

Vitamin D3: how much does she suggest?

Dr Sims identifies vitamin D3 as another supplement she considers important.

She connects vitamin D with musculoskeletal health and discusses potential relationships with cardiovascular health, brain function and iron regulation.

Huberman asks about amounts such as 1,000 IU and 5,000 IU daily.

Dr Sims responds that requirements may vary with geography, season, sun exposure and lifestyle.

Dr Sims discusses approximately 2,000–5,000 IU daily, particularly for people living at northern latitudes. This is her recommendation, not routine UK supplementation guidance. The NHS recommends considering 400 IU daily during autumn and winter and advises adults not to exceed 4,000 IU daily unless directed by a doctor. Her suggested upper amount of 5,000 IU exceeds that general limit.

This is one of the recommendations that needs clear separation from routine UK public-health guidance.

Protein powder: supplement your diet rather than replace meals

Dr Sims also recommends high-quality protein powder as a practical option.

Her reasoning is straightforward: some women find it difficult to obtain their intended daily protein intake entirely through meals.

Protein powder can help bridge the gap between what someone eats and what they need for their training goals.

But Dr Sims distinguishes supplementation from replacing a balanced diet.

Her emphasis remains on adequate total nutrition, with powder used when convenient or necessary.

Adaptogens: ashwagandha, tulsi and schisandra

The conversation then shifts to plants described as adaptogens.

Dr Sims mentions:

• Ashwagandha.
• Holy basil, also called tulsi.
• Schisandra.

She describes differences in how she believes these substances affect stress, alertness and relaxation.

Schisandra is her preferred example for focus and mental energy.

She explains that she sometimes adds it to her morning coffee and uses it later in the day instead of additional caffeine.

She contrasts its perceived stimulating properties with the more calming effects she attributes to ashwagandha and tulsi.

These are her descriptions of proposed effects, not proof that these products reliably improve concentration or regulate stress hormones.

Ashwagandha has been linked to rare liver injury, can affect thyroid function and may interact with medication; it should be avoided during pregnancy and breastfeeding. Clinical efficacy and safety for schisandra, tulsi and medicinal mushrooms need separate evaluation.

Medicinal mushrooms: lion's mane and reishi

Dr Sims also discusses medicinal mushrooms, particularly lion's mane and reishi.

She places them among supplements she considers when discussing mental performance, stress and general wellbeing.

The interview does not establish a clinically validated dose or treatment protocol for these mushrooms.

Their usefulness for particular symptoms needs evaluation through appropriate human studies, rather than inferred from their popularity or traditional use.

Should adaptogens be taken in the morning or evening?

Huberman asks an important question about cortisol.

Cortisol naturally follows a daily rhythm, generally rising around waking and declining later in the day.

If a supplement is intended to influence stress-related pathways, does timing matter?

Dr Sims says women should not aim to suppress cortisol throughout the day.

She describes cortisol fluctuations as normal and necessary.

For supplements she considers more calming, such as ashwagandha and tulsi, she discusses taking them around 4 pm, when cortisol would normally be declining.

For schisandra, which she considers more stimulating, she prefers morning or afternoon use.

She also mentions that some supplements may need to be taken cyclically rather than continuously.

Huberman specifically raises concerns about prolonged high-dose ashwagandha use, including possible liver and thyroid problems.

Her overall supplement philosophy

Dr Sims does not argue that women should take every supplement discussed.

Instead, she asks what problem the person is trying to address.

Is the goal strength, mental focus, recovery, sleep or something else?

She wants the choice of supplement to follow that question, rather than women buying products because they are fashionable.

Her interview places creatine, vitamin D and adequate protein at the centre of the discussion, followed by more individualised consideration of adaptogens and medicinal mushrooms.

The final distinction is essential: describing a supplement as useful in an expert interview does not automatically establish clinical benefit, appropriate dosing or suitability for every woman.

Pregnancy, Exercise After 50 and High-Intensity Training: What Does Dr Stacy Sims Recommend?

Should pregnant women stop lifting weights? Can jumping improve bone density after menopause? And when Dr Stacy Sims tells women to exercise at high intensity, what does she actually mean?

Her recommendations are specific: maintain fitness during pregnancy, prioritise strength and bone health as women age, and distinguish genuinely intense exercise from workouts that simply leave you exhausted.

Pregnancy: should women stop exercising?

Dr Sims argues that pregnancy is not automatically a reason to abandon an established exercise routine.

She explains that pregnancy brings significant physiological adaptations. Blood volume expands, while the capacity for demanding anaerobic exercise can decrease.

Rather than fighting those changes, she recommends adjusting expectations.

Her central distinction is maintaining fitness rather than trying to make new performance gains.

For women accustomed to weight training, that means continuing appropriate resistance training without necessarily trying to lift progressively heavier loads.

For someone who enjoys a cardiovascular exercise class, the session can remain valuable for movement and social connection, even when she cannot sustain her previous intensity.

Dr Sims is particularly concerned about previously active women becoming completely inactive because they are afraid of exercising during pregnancy. She argues that unnecessary inactivity can lead to deconditioning.

She also notes that research involving pregnant women has limitations, with some recommendations informed by observational evidence and individual cases.

Her position is to remain appropriately active, adapt exercise to pregnancy and avoid pursuing new performance records.

Hot yoga, saunas and cold plunges during pregnancy

Huberman raises a question he says he receives frequently: is deliberate cold-water immersion safe during pregnancy?

He does not offer a definitive answer and favours caution.

Dr Sims also expresses concern about cold exposure, particularly in pregnancies with increased risks. She discusses how substantial physiological stress may be problematic in vulnerable circumstances.

Her view of heat exposure is different.

She distinguishes hot yoga at approximately 40°C from much hotter sauna exposure.

Dr Sims discusses possible changes in placental blood flow and vascular adaptation in response to exercise and moderate heat.

Her proposed explanation is that certain physiological stresses can stimulate vascular responses that support nutrient delivery to the developing baby.

However, she does not encourage women to push through overheating. Her discussion emphasises recognising excessive heat, leaving the activity when necessary and avoiding extreme exposure.

This is one area where Dr Sims' claims require particularly careful independent verification.

ACOG advises avoiding hot yoga and hot Pilates during pregnancy because of overheating risks; Dr Sims' discussion of potential heat adaptations should not be taken as an endorsement of these activities.

Women over 50: Dr Sims' four priorities for healthy ageing

When Huberman asks what women over 50 should do to maximise health and longevity, Dr Sims asks a different question:

What physical abilities will women need to remain independent at 80 or 90?

She identifies balance, proprioception (knowing where your body is positioned), strong bones, muscular strength and independent movement.

From there, she builds her recommendations around four priorities.

1. Jump training — approximately ten minutes, three times weekly

Dr Sims argues that bones benefit from mechanical loading and impact.

She is not simply discussing gentle movements. She describes jumping that places an impact stimulus through the skeleton.

She refers to work by researcher Tracy Cassels and describes women whose bone measurements reportedly improved from the osteopenic range to the normal range after approximately four months of this type of training.

Dr Sims makes a striking claim about losing approximately one-third of bone around the menopausal transition without intervention. However, the interview's exact measurement, population and timeframe require verification before this figure can be interpreted. It should not be presented as a typical or inevitable amount of bone loss for women approaching menopause.

These figures are part of her interview. They are not independently verified clinical outcomes or representative estimates for all women.

2. Heavy resistance training

Dr Sims wants older women to develop the strength needed for daily activities and long-term independence.

She distinguishes this from exercise undertaken solely to burn calories or change appearance.

She also explains that the training emphasis changes with age. Younger women can often place more emphasis on training to muscular failure and building muscle size; older women may particularly benefit from progressively developing strength through appropriately challenging loads.

3. Sprint interval training

She recommends brief, very demanding exercise to challenge cardiovascular and metabolic systems.

This does not necessarily mean running. Cycling, rowing and other suitable activities can provide similar kinds of effort.

4. Adequate protein

Dr Sims considers protein particularly important for maintaining muscle as women age.

Dr Sims recommends approximately 2–2.3g of protein per kilogram of body weight daily for women pursuing the training goals discussed in the interview. For comparison, the International Society of Sports Nutrition's female-athlete position statement recommends 1.4–2.2g/kg/day. Dr Sims' recommendation is therefore at the upper end of, and slightly beyond, that range. It should not be interpreted as a requirement for every woman.

For example, her proposed target would amount to approximately 120–138 grams daily for a woman weighing 60kg.

Huberman discusses examples such as eggs, chicken and steak. Dr Sims emphasises that protein can also come from beans and other plant foods.

Her combined message is that jumping, heavy resistance training, sprint intervals and protein work together to support strength, body composition and long-term function.

Impact exercise can support bone health, but repeated jumping may require modification or professional assessment for those with osteoporosis, fragility fractures, significant joint problems or balance difficulties.

Women in their 20s, 30s and 40s: build strength before you need it

For younger women, Dr Sims starts with enjoyment.

She questions why someone who hates running should feel compelled to run. An exercise routine should be something a woman can continue rather than a chore she eventually abandons.

But she also emphasises structured resistance training.

Women in their 20s through 40s should establish a foundation of strength and movement skills.

She discusses different ways to achieve this:

• Resistance training with machines or free weights.
• Periodised training, in which exercises, loading and objectives change across planned blocks.
• Learning complex movements before attempting demanding loads.
• Introducing heavier or more powerful movements as experience develops.

She explains that younger women often have more flexibility in their training, while women approaching their 40s benefit from paying closer attention to strength, recovery and high-intensity exercise.

Lactate, fast-twitch muscle fibres and the ageing brain

This is one of Dr Sims' more interesting arguments.

She explains that women generally have a greater tendency towards oxidative metabolism and may have fewer highly glycolytic muscle fibres than men.

Glycolytic fibres are particularly important for producing rapid, powerful contractions during intense exercise.

Dr Sims argues that high-intensity exercise challenges these fibres and increases lactate production.

Lactate is not merely a waste product associated with muscle fatigue. It can also be used as a fuel and participates in signalling processes.

Dr Sims connects this to brain health.

Her hypothesis is that regular exposure to exercise-related lactate may influence brain metabolism and help protect against aspects of cognitive ageing.

She goes further, discussing possible relationships between lactate metabolism, cognitive decline and Alzheimer's-related brain changes.

This is the reason she particularly wants women in their 40s and beyond to incorporate genuinely demanding intervals, rather than relying entirely on moderate-intensity exercise.

She also discusses how training can influence the characteristics of fast-twitch muscle fibres as women age.

DrSheikh evidence distinction: Lactate has established physiological roles, but the interview's proposed protection against Alzheimer's disease must not be represented as proven dementia prevention. The strength of the human clinical evidence requires separate examination.

What does Dr Sims actually mean by HIIT?

Huberman asks Dr Sims to clarify an important misunderstanding.

Many people describe any sweaty, exhausting workout as high-intensity interval training.

Dr Sims says that feeling exhausted does not necessarily mean a workout has delivered the type of high-intensity stimulus she recommends.

She explains two different approaches.

1. High-intensity interval training: one to four minutes of demanding work

For runners, Dr Sims describes repeated 400-metre or 800-metre track efforts.

These involve approximately one to four minutes at 80% effort or higher, followed by sufficient recovery.

For example, a runner might complete a hard lap, walk part of the track and then repeat.

The session is demanding, but it is not designed to continue indefinitely.

Dr Sims suggests that a track session of this kind might take approximately 30–40 minutes, including the necessary recovery periods.

These high-intensity intervals are examples rather than universal requirements. Appropriate intensity depends on fitness, experience and health conditions; maximal efforts may be unsuitable without medical assessment for some readers.

Her specific gym-based HIIT circuit

Dr Sims also describes a gym session structured around four consecutive exercises.

Each exercise occupies roughly one minute.

She describes roughly ten seconds to transition between exercises when a set finishes before the minute is over.

After the four minutes of work, there is one full minute of rest. The sequence is repeated three times.

Huberman asks whether this should be considered resistance training for muscular strength.

Dr Sims says no.

The purpose of this particular circuit is cardiovascular high-intensity training, even though resistance exercises and weights are used.

That distinction is important: using weights in a demanding circuit is not necessarily equivalent to a strength-building session.

2. Sprint interval training: 30 seconds or less at maximum effort

Dr Sims then distinguishes sprint interval training (SIT) from longer HIIT efforts.

For SIT, she describes efforts lasting 30 seconds or less at near-maximal intensity.

She characterises the effort as approximately 9–10 out of 10 on a perceived-exertion scale.

The activity might be:

• Sprinting, for someone accustomed to running.
• Cycling on an exercise bike.
• Using a rowing machine or ski ergometer.
• Performing demanding intervals with battle ropes.

The important point is that the effort must be genuinely intense.

Why two or three minutes of recovery matters

Huberman asks whether someone should rest for only ten or fifteen seconds after a sprint.

Dr Sims disagrees.

She explains that two to three minutes of recovery may be needed between near-maximal efforts.

Her reasoning concerns replenishing the body's immediate energy systems, including ATP-related processes, and allowing the nervous system to recover sufficiently.

Without enough recovery, the next repetition may not achieve the intended intensity.

She distinguishes this approach from shorter-rest interval methods such as Tabata-style workouts.

For Dr Sims, a properly recovered near-maximal sprint is not equivalent to repeatedly exercising while increasingly exhausted.

These are examples from the interview and should not be undertaken as an unassessed beginner protocol.

Why she favours polarised training over constant moderate intensity

Dr Sims' final point is that women should not make every session moderately difficult.

She advocates polarised training: combining genuinely demanding workouts with lower-intensity recovery activity.

For example, high-intensity sessions might be separated by easier movement such as walking.

She describes the difference between a deliberately easy recovery session and a moderate-paced run that introduces additional fatigue without providing the specific high-intensity stimulus she wants.

Earlier in the interview, she discusses combining approximately three to four resistance-training sessions with one or two higher-intensity sessions, adjusted for age, experience, goals and recovery.

Why she believes these training intensities matter metabolically

Dr Sims argues that the purpose of challenging exercise is not simply to burn calories or produce a particular appearance.

She describes several physiological adaptations she hopes to stimulate.

Glucose uptake: She discusses how intense exercise can affect muscle glucose transport, including GLUT4 proteins involved in moving glucose into muscle cells.

Inflammation and recovery: She describes how a demanding exercise stimulus can create a temporary inflammatory response, followed by adaptations that help the body manage subsequent stress.

Changes during menopause: Dr Sims connects the decline in oestrogen with changes in inflammation, fat metabolism and the tendency to accumulate visceral fat.

Brain and muscle communication: She proposes that intense exercise influences both muscular metabolism and neural adaptations important for ageing.

Her larger argument is that well-chosen training stresses can create adaptations that support function decades later.

These mechanisms provide the reasoning behind her recommendations, but they do not establish that every suggested protocol improves every claimed long-term outcome in human clinical trials.

The lasting message from this part of the interview is that Dr Sims wants women to train with a purpose: preserve muscle, strengthen bones, challenge cardiovascular and metabolic systems, and maintain the physical capacity to live independently as they age.

Women's Nutrition, the 80/20 Rule and Listening to Your Body: Dr Stacy Sims' Final Advice

After discussing strength training, sprint intervals, hormones and longevity, Dr Stacy Sims returns to a question that affects virtually every woman trying to improve her health:

What should women actually eat to support their training — and how strict do they need to be?

Her answer combines sufficient protein, carbohydrate-rich whole foods, dietary variety and flexibility. She also ends the interview with a wider message about women learning to recognise their own bodies' needs.

Carbohydrates: Dr Sims does not want women to fear them

Andrew Huberman asks Dr Sims which foods she recommends alongside the high protein intakes discussed earlier.

He specifically raises carbohydrates used to replenish muscle glycogen after strength training and high-intensity exercise.

Dr Sims does not argue that women should eliminate carbohydrates.

Instead, she gives examples of foods she likes women to include:

• Colourful fruits and vegetables.
• Sweet potatoes, kumara and yams.
• Sprouted-grain bread.
• Quinoa and amaranth.
• Other suitable carbohydrate-rich foods chosen around individual training needs.

Her preference is to obtain most carbohydrates from minimally processed foods while making sure women have enough fuel for the exercise they perform.

But she also acknowledges that food choices are not always perfect.

What about breakfast cereals and ultra-processed foods after exercise?

This is one of the more revealing exchanges.

Dr Sims explains that some athletes she works with enjoy children's breakfast cereals, including Coco Pops.

Huberman says he prefers foods such as rice, oatmeal and sourdough bread.

Dr Sims does not respond by insisting that her athletes must never eat cereal.

She suggests that if someone particularly wants that food, it can be incorporated after training — for example, added to yoghurt as part of their carbohydrate intake.

Huberman connects this to increased muscle glucose uptake following exercise, referring to GLUT4 transporters and replenishing glycogen stores.

Dr Sims nevertheless makes her general preference clear: everyday carbohydrate choices should predominantly come from foods such as fruit, vegetables and minimally processed grains.

The distinction is between a preferred dietary pattern and allowing individual foods to fit within it.

This is how the exchange is presented in the interview; it does not establish that ultra-processed cereals become inherently healthy because they are eaten after exercise.

Gut microbiome diversity: why Dr Sims emphasises fibre and colourful plants

Dr Sims then moves from carbohydrates to the gut microbiome.

She argues that microbial diversity is particularly important for women because gut bacteria interact with hormone metabolism.

She discusses how intestinal microorganisms participate in processes that can influence whether certain hormone compounds are metabolised, eliminated or returned to circulation.

Dr Sims connects this relationship to changes occurring during hormonal transitions.

Her dietary response is straightforward: encourage a broad variety of fibre-containing foods, particularly colourful fruits and vegetables.

Rather than focusing exclusively on protein grams and exercise schedules, she wants women to consider the diversity of foods feeding their gut microbiome.

The proposed links between specific microbiome changes, hormone recycling and women's long-term health outcomes require separate scientific examination.

The 80/20 rule: what about chocolate and whiskey?

Dr Sims does not advocate a diet in which every meal must be perfect.

She describes an 80/20 approach: aim for nutritious choices most of the time while leaving room for ordinary enjoyment and flexibility.

She playfully raises chocolate and whiskey as examples of things people may enjoy.

Huberman responds by mentioning research into chocolate, particularly varieties containing less sugar.

Dr Sims' emphasis is not on turning those foods or drinks into treatments.

Her point is that a sustainable approach to nutrition has room for personal enjoyment, rather than requiring constant restriction.

The 80/20 rule is her practical philosophy, not a clinically validated formula requiring anyone to obtain exactly 80% of their calories from particular foods. The discussion of alcohol should not be interpreted as a recommendation to drink for health.

Where does Dr Sims recommend getting dietary fats?

Huberman then asks which fat sources Dr Sims prefers.

She explains that she has personally been vegan since high school, following an experience visiting a pig slaughterhouse.

However, she distinguishes her personal dietary choice from what she recommends to others.

She favours obtaining most dietary fats from whole plant foods, while recognising that animal foods may also have a place in individual diets.

She names examples including:

• Avocados.
• Nuts and seeds.
• Olive oil.
• Butter.
• Full-fat yoghurt.

Dr Sims argues against simplistic fear of dairy-derived saturated fat and favours a mixed approach to food choices.

Her emphasis is on the overall quality and variety of dietary fat sources, with a preference for minimally processed foods.

Her broad dismissal of concerns about saturated fat should be treated as her interpretation, not proof that all saturated-fat sources or intake levels have equivalent cardiovascular effects. Independent dietary evidence review is still required.

Nutrition is fuel for training — not simply a way to eat less

Huberman summarises one of the central lessons he has taken from the conversation.

Women are frequently encouraged to restrict food, yet demanding exercise creates physiological needs that must be met.

He describes how eating enough high-quality food supports training, while training creates changes in muscles and metabolism.

Dr Sims agrees.

The interview's recurring message is that women should not pursue demanding exercise while chronically under-fuelling themselves.

This connects directly to her earlier discussions about fasted exercise, recovery, preserving lean mass and hormonal responses to insufficient energy intake.

Her position is not that every woman must eat identical quantities. It is that nutrition must be considered alongside exercise intensity, recovery and individual circumstances.

If Dr Sims could change one thing for women everywhere, what would it be?

Huberman closes with a question: if she could encourage women everywhere to make one important change, what would she choose?

Her answer is not another protein target, supplement or training protocol.

She wants women to understand themselves and pay attention to the signals their own bodies are sending.

Dr Sims argues that cultural expectations, outside advice and social pressure have made many women less confident about recognising what they need.

She says that helping women relearn this awareness is a recurring part of her work.

Her examples include understanding menstrual-cycle patterns, recognising changing needs during perimenopause, and becoming more aware of how the body responds to training and other stressors.

She also emphasises that perimenopause is a normal life transition, rather than something women should feel ashamed of or ignore.

Only when women better understand their individual responses, she argues, can they choose exercise and nutrition strategies that genuinely benefit them.

The final message from Dr Stacy Sims

Throughout the interview, Dr Sims challenges the assumption that women should simply follow exercise and nutrition approaches developed without sufficient attention to female physiology.

Her recommendations span strength training, high-intensity exercise, adequate fuelling, menstrual-cycle awareness, recovery and healthy ageing.

But her closing argument is broader.

Women need both scientific information and the confidence to recognise their individual needs.

For Dr Sims, the goal is not simply to become lighter, train harder or follow more rules. It is to develop the strength, physical capacity and self-awareness needed to remain healthy and independent throughout life.

Here's the Catch: Does the Science Support Everything Dr Stacy Sims Recommends?

Dr Stacy Sims makes a compelling case for taking women's physiology seriously when designing exercise and nutrition programmes.

But there is an important distinction between a plausible biological explanation, a promising research finding and a recommendation proven to improve women's long-term health.

Here are some of the questions readers should keep in mind.

1. Not every difference between women and men requires a different exercise programme

Dr Sims argues that women have distinct hormonal, metabolic and recovery characteristics.

That's an important area of research. But women also differ considerably from one another.

Age, training experience, health, fitness and individual response can matter as much as biological sex. A result observed in female athletes does not automatically apply to every woman.

2. Menstrual-cycle changes do not justify one rigid training calendar

Dr Sims discusses how oestrogen and progesterone can influence sleep, metabolism and training responses.

However, the evidence does not establish one optimal workout schedule for every phase of every woman's menstrual cycle.

Recognising personal patterns is different from assuming all women will perform better or worse on particular cycle days.

3. Some numerical recommendations are more specific than the evidence behind them

The interview includes memorable figures:

• Protein: approximately 2–2.3g per kilogram of body weight daily.
• Jump training: around ten minutes, three times weekly.
• Creatine: approximately 3–5g daily.
• Vitamin D: approximately 2,000–5,000 IU daily.
• Sauna exposure: up to 30 minutes after exercise.

These numbers are worth examining individually.

They are Dr Sims' recommendations, not universal prescriptions. Their suitability depends on the purpose, supporting evidence, individual health and potential risks.

For example, her upper vitamin D suggestion exceeds the NHS's usual adult upper limit of 4,000 IU daily unless medically directed.

4. Promising brain-health mechanisms are not proof of dementia prevention

One particularly interesting argument concerns lactate produced during high-intensity exercise.

Dr Sims describes how lactate participates in energy metabolism and signalling, and proposes potential benefits for the ageing brain.

But showing that lactate has important biological functions does not prove that sprint intervals prevent Alzheimer's disease.

That would require appropriate human clinical evidence assessing meaningful outcomes.

5. Emerging women's health research is not yet an established diagnostic service

The interview explores menstrual-fluid testing, PCOS, reproductive hormones and contraceptive-related performance changes.

These subjects deserve attention.

But a promising biomarker is not automatically a validated diagnostic test. Likewise, an association between a contraceptive formulation and athletic performance does not prove that changing contraception will improve someone's results.

Clinical decisions require more than an interesting research hypothesis.

6. Supplements and recovery practices carry different levels of uncertainty

Creatine, vitamin D, protein powders, adaptogens and medicinal mushrooms are not interchangeable simply because they're discussed together.

Their evidence, doses, interactions and safety profiles differ.

Similarly, cold plunges, saunas and high-intensity workouts can place significant demands on the body.

Particular care is needed during pregnancy and for women with cardiovascular conditions, osteoporosis, medication-related risks or other relevant health concerns.

So, should women disregard Dr Sims' advice?

No. That would miss the value of the interview.

Dr Sims raises important questions about under-fuelling, strength, bone health, female-specific research and the tendency to overlook women's experiences.

Her discussion also provides useful practical distinctions between strength training, cardiovascular intervals, sprint training and recovery.

The sensible conclusion is neither to accept every recommendation unquestioningly nor to dismiss the interview because some claims remain uncertain.

Understand what Dr Sims recommends, examine the quality of evidence for each claim, and distinguish general principles from interventions that require individual assessment.

Next View Point

Dr Stacy Sims' interview raises several questions worth following as new research emerges.

We will particularly watch for stronger human evidence on creatine and women's brain health, the effects of menstrual-cycle phases on training performance, exercise strategies during perimenopause and menopause, and whether sauna exposure can meaningfully improve hot flushes or recovery.

We'll also follow developments in menstrual-fluid diagnostics, female-specific research into high-intensity training, and the safety and effectiveness of supplements promoted for women's health.

When substantial findings become available, we'll revisit the relevant claims and record meaningful changes in the dated Updates to This Story section.