Dr. Stacy Sims — Exercise physiologist and nutrition scientist who has authored over 100 peer-reviewed studies and the bestselling books Roar and Next Level. She is a research scientist at AUT in New Zealand focused on sex differences in exercise and nutrition.
The gist
Dr. Stacy Sims argues that almost all sports science and nutrition research is built on male data, leaving women to be wrongly generalized to it. She walks through the physiological differences between men and women - muscle morphology, the Q angle, hormones, the hypothalamus and gut microbiome - and how they change training, fueling, fasting, cold/heat exposure, and supplement needs. She covers the menstrual cycle phase by phase, perimenopause and menopause, and what women should do differently around protein, resistance training, and recovery. Throughout, she challenges popular trends like fasting, keto, and cold plunges as being inappropriate for women, and reframes hormone therapy as attenuating change rather than anti-aging.
Big reveals
- Most sports science studies recruit 18-22 year old college-age men, so women have been generalized to male data.
- As a student, Sims had her own lab results thrown out as an 'anomaly' for not matching the men's data.
- By age 14, over 60% of previously sporty girls drop out of sport because nobody explains their changing bodies.
- Warrior-style fasting (20-hour fast) backfires for women, raising blood glucose, increasing fat storage, and downturning the thyroid within four days.
- Cold plunges at 0-4C are 'male data' - women need warmer water around 15-16C to get the same benefit.
- Women only need 3-5g of creatine once daily, not the bodybuilding loading protocol, and it aids gut, brain, and mood, not just muscle.
- Blood-test reference ranges have been quietly shifting to fit a sicker, more sedentary population.
- Three years ago women in their 40s were often handed an SSRI instead of being told they were in perimenopause.
Things worth remembering
- Essential body fat is ~4-8% for men but ~12% for women, with healthy ranges around 15% (men) and 20% (women).
- Women tear their ACL at roughly a 3-to-1 or 4-to-1 ratio compared to men, linked to the wider Q angle and quad dominance.
- Baseline calorie need to avoid hormone dysfunction is ~15 cal/kg of fat-free mass for men but ~30 for women.
- Exercise is a stronger stimulus for autophagy than fasting.
- Metabolism returns to baseline within 30-40 minutes for women after exercise but takes 2-18 hours for men.
- Women in reproductive years need ~35g of protein within 45 minutes post-exercise; men need ~20g with a much wider window.
- Women's melatonin peaks around 9pm versus 10-11pm for men, making women suffer more from jet lag, especially traveling west.
- Many women now have anovulatory cycles yet still bleed, and up to 55% of recreational female athletes are in a low-energy-availability state.
- Sims calls it 'menopause hormone therapy' not 'hormone replacement' - it attenuates change, not restores youth, and has no proven dementia benefit.
- Perimenopause can span ~15-17 years from around age 35 to the average menopause age of 52.
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Next Level
Dr. Stacy Sims
“Next level, which is your guide to kicking ass, feeling great, and crushing goals through menopause and beyond” — Steven Bartlett 02:00:20Find it on Amazon
Roar
Dr. Stacy Sims
“your book raw, which is match your food and fitness to your unique female physiology for optimal performance, great health, and a strong body for life” — Steven Bartlett 02:00:20Find it on Amazon