Fasting
From our Stacy Sims profile
Sims advises active women never to train fasted or use long fasting windows; Haver's Galveston Diet originally built in 16:8 intermittent fasting (she has since pulled back).
Compare experts › Stacy Sims vs Mary Claire Haver
Stacy Sims vs Mary Claire Haver
Stacy Sims (exercise physiologist) and Mary Claire Haver (physician, ob-gyn) side by side: how they train, eat, supplement and sleep, how strong the evidence is, and how to build a plan from either or both.
Words explained (10)
- Zone 2
- Steady cardio at a pace where you can still talk in full sentences, but not sing.
- Intervals
- Short hard efforts with easy recovery in between, such as 30 seconds fast, 90 seconds slow.
- Loaded carry
- Walking while holding something heavy, like shopping bags or dumbbells.
- Mobility
- Moving your joints freely through their full range.
- Creatine
- A well-studied supplement that supports strength and muscle.
- Omega-3 (EPA, DHA)
- Healthy fats found mostly in oily fish such as salmon, herring and sardines.
- Fibre
- The part of plant foods you don't digest. It feeds healthy gut bacteria and keeps you full.
- Time-restricted eating
- Eating all your meals within a set window of the day, for example 8am to 6pm.
- Perimenopause
- The years of changing hormones before periods stop for good.
- Hormone therapy (HRT, MHT)
- Medicine that replaces hormones that fall at menopause. Only a doctor can prescribe it.
At a glance
| Measure | Stacy Sims | Mary Claire Haver |
|---|---|---|
| Background | Exercise physiologist | Physician, OB-GYN |
| Training split | 60% strength · 10% aerobic · 25% intervals · 5% mobility | 55% strength · 40% aerobic · 0% intervals · 5% mobility |
| Signature habit | Heavy lifts + sprints | Fibre 25 g+ a day |
| Protein | ~2.2 g/kg | 80–120 g a day |
| Training style | Women 40+ | Women 40+ |
| Overall evidence | Strong | Strong |
| Following | Instagram 1.4M · YouTube 372K | Instagram 3.6M · YouTube 688K |
Training splits are our estimates from each expert’s published routine. Following checked October 2026.
The key differences
- Haver puts more of the week into aerobic base (zone 2): about 40% against 10%.
- Sims puts more of the week into intervals: about 25% against 0%.
- In plans in their style, Sims' hard sessions are short sprints; Haver's are 1-minute intervals.
- We rate the overall evidence behind both protocols as strong.
- Supplements that go into a plan: Sims, creatine monohydrate; Haver, none (food first). Prescription items and personal stacks stay out of every plan.
- Neither has a separate mobility routine; plans add 10 minutes a day of basics.
Where they disagree
Cardio
From our Stacy Sims profile
Sims plays down zone 2 and moderate cardio for midlife women; Haver's plan includes walking at least 3 days a week alongside lifting.
Fasting
From our Mary Claire Haver profile
Haver's original Galveston Diet used 16:8 intermittent fasting (she has since softened this); Stacy Sims advises active women not to train fasted or use long fasting windows.
Cardio
From our Mary Claire Haver profile
Haver recommends walking at least 3 days a week alongside lifting; Sims plays down moderate and zone 2 cardio for midlife women in favour of very short sprints.
Protein
From our Mary Claire Haver profile
Haver sets about 1.3–1.8 g/kg of healthy body weight; Sims aims higher, around 2.2 g/kg for active women in menopause.
Protocols side by side
Each line is rated for the evidence behind it. “Doctor only” items never go into a plan.
Training
Stacy Sims
- Strength training 3–4 times a week, 45–60 minutes, built on compound liftsStrong evidence
- From perimenopause, lift heavy: about 3–5 sets of 6 reps or fewer, leaving 2–3 reps in reserve, with 2+ minutes restSome evidence
- Sprint intervals of 30 seconds or less, all-out, with full recovery; 1–2 sessions a weekSome evidence
- Jump and impact work (e.g. squat jumps, box jumps) for bone; one studied protocol is 10–20 jumps twice a daySome evidence
- Keep easy cardio (walking, easy rides) as recovery; she plays down long moderate-intensity sessions and zone 2 for midlife body-composition goalsPersonal habit
- 'Ten-minute rule': if you still feel flat after a 10-minute warm-up, scale the session downPersonal habit
Mary Claire Haver
- Full-body weight training at least 2 days a week (she does 3–4), progressing gradually, ideally with a trainerStrong evidence
- Walk at least 3 days a week; beginners start with 5–10 minutes a dayStrong evidence
- To progress: add a weighted vest to walks, more steps, or a third lifting dayPersonal habit
- No exercise types need to be avoided in menopause; strength, cardio, stretching and mind-body work all matterNote
Eating
Stacy Sims
- Do not train fasted: about 15 g protein before lifting, plus about 30 g carbohydrate before cardio of up to an hourSome evidence
- After training: 40–60 g protein (perimenopause on) within about 45 minutes, and carbohydrate within 2 hoursSome evidence
- Daily protein around 2.2 g/kg body weight, the top of the 1.4–2.2 g/kg range in her ISSN position standSome evidence
- Protein at meals 30–40 g, snacks 15–20 gSome evidence
- Avoid long fasts, keto and big calorie cuts if active; a small deficit (about 150–200 kcal) in the evening, away from training, if aiming to lose fatPersonal habit
Mary Claire Haver
- Protein about 1.5 g per kg of healthy body weight a day, with about 1.8 g/kg as a stretch goalSome evidence
- Fibre at least 25 g a day, building slowly towards 30–45 gStrong evidence
- Eat about 30 different plant foods a week (vegetables, fruit, nuts, seeds, grains, herbal teas)Some evidence
- Anti-inflammatory, Mediterranean-style eating: limit added sugar and processed carbohydrate, add leafy greens, olive oil, berries, nuts and fermented foodsStrong evidence
- Spread protein across meals and snacks, each paired with a healthy fat and a healthy carbohydratePersonal habit
- She originally promoted 16:8 intermittent fasting but has pulled back, saying it can make enough protein hard to reachNote
Supplements
Stacy Sims
- Creatine monohydrate 3–5 g a day (start with 1–2 g if unsure), paired with strength trainingStrong evidence
- Choose third-party tested products (NSF or Informed Sport)Note
- Vitamin D3, omega-3, collagen and turmeric mentioned as options; no doses givenPersonal habit
- Iron only if a blood test shows low ferritinDoctor only
Mary Claire Haver
- Omega-3, vitamin D and vitamin K among the supplements she takes; she does not give general dosesPersonal habit
- Fibre supplement if diet alone falls short of the daily targetPersonal habit
- Check with your doctor before starting any new supplementNote
- She sells her own supplement line ('Pause), so weigh her product recommendations with that in mindNote
Sleep & recovery
Stacy Sims
- Traditional (Finnish-style) sauna at about 60–80 °C after training; she prefers heat to cold for womenSome evidence
- If using cold water, choose cool (about 16 °C) rather than ice-coldPersonal habit
- Treat easy days as true recovery between hard sessionsPersonal habit
- Sees hormone therapy as a valid option for hot flushes and bone risk, but not required for every womanDoctor only
Mary Claire Haver
- Menopausal hormone therapy, chosen with a doctor; she calls it the most effective treatment for hot flushes and night sweatsDoctor only
- Prefers non-oral (patch, gel, spray) oestrogen, which carries a lower clot risk than tablets; progesterone for women with a uterusDoctor only
- Magnesium (L-threonate) and a sleep supplement in her own routinePersonal habit
Stress & mind
Stacy Sims
- Keep hard intervals short; she says longer efforts and very long sessions raise cortisol, already a concern in menopauseSome evidence
- In perimenopause, have caffeine with food before training if it makes you shaky or light-headedPersonal habit
- Listen to your own body and track responses rather than following a fixed planPersonal habit
Mary Claire Haver
- Journal for a few minutes every dayPersonal habit
- Add meditation, using an app or free guided sessionsSome evidence
- Prepare questions before midlife health check-ups and push for proper care of symptomsPersonal habit
Brain health
Stacy Sims
- Creatine for brain fog and mood; she cites a trial where 5 g a day added to an antidepressant helped women with depressionSome evidence
- Favours truly hard intervals over moderate or zone 2 cardio for midlife cognitive and metabolic benefitsSome evidence
Mary Claire Haver
- Points to observational data linking longer lifetime oestrogen exposure, including hormone therapy, with better cognition; not a licensed reason to start hormonesDoctor only
- Creatine for possible memory and mood benefits; most of this evidence is from small or non-menopausal studiesSome evidence
- Strength training, protein and fibre as part of reducing long-term risks such as dementia, heart disease and diabetesSome evidence
Weak spots to know
Stacy Sims
- Some researchers say her sex-specific advice goes beyond the evidence. A 2023 umbrella review co-authored by Stuart Phillips found no clear effect of menstrual-cycle phase on strength or training gains, and Sims publicly debated Lauren Colenso-Semple in 2025 on fasted training and protein timing, framed as mechanisms versus outcomes.
- Her case against fasted training leans heavily on short-term hormone and appetite responses; critics note that longer studies measuring actual fat loss and muscle gain show little difference when daily calories are adequate.
- Many of her menopause-specific prescriptions (exact sprint lengths, playing down zone 2, tight post-exercise protein windows) come from extrapolation and her own coaching experience rather than trials in midlife women.
Mary Claire Haver
- Several menopause specialists, quoted in a 2024 New York Times report, said she promotes hormone use beyond official guidelines; one said patients now ask for hormones to prevent heart disease or dementia, or testosterone for general wellbeing.
- Commercial ties, stated neutrally: she owns The 'Pause Life (a multimillion-dollar business selling supplements, programmes and online courses) and a cash-pay menopause clinic. The Menopause Society discourages doctors from selling their own products, and the advertising watchdog Truth in Advertising flagged some product claims; according to the New York Times, she then hired a consultant to review the claims on her website.
- An independent review by ConsumerLab found some of her supplements costly for what they contain, with creatine claims that overstate the evidence and a vitamin D dose at the upper safe limit.
Build a plan from Sims, Haver or both
Your free plan shows a week of gym sessions, cardio, a day of eating, supplements and mobility, fitted to your age, time and health.
Questions
What is the main difference between Stacy Sims and Mary Claire Haver?
Their training split differs most in aerobic base (zone 2): Sims about 10%, Haver about 40% (our estimate from their published routines). Sims' signature habit is Heavy lifts + sprints; Haver's is Fibre 25 g+ a day.
How much protein do Sims and Haver recommend?
Sims: ~2.2 g/kg. Haver: 80–120 g a day.
Whose advice has stronger evidence?
We rate the overall evidence behind both protocols as strong.
Do Sims and Haver disagree?
Yes, on fasting, cardio, protein. See "Where they disagree" on this page.
Can I combine Sims and Haver?
Yes. In Build my mix you choose one expert per area, for example one for strength and another for eating. Your free plan shows the result straight away.
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Full sources are on each profile: Stacy Sims · Mary Claire Haver. Reviewed October 2026.