Why Women Gain Weight on the Same Diet as Men: Fueling, Fasting, and Biology with Dr. Stacy Sims

In this episode of unPAUSED, Dr. Mary Claire Haver sits down with exercise physiologist and nutrition scientist Dr. Stacy Sims to unpack why so much fitness and diet advice built on male physiology leaves women confused about why the scale will not move, and why weight loss can feel so much harder for women than for men on the exact same plan. Dr. Sims, author of Roar and Next Level, a former professional cyclist who has taught and coached at Stanford, breaks down why women following the same diet and training program as their male partners often end up tired and stuck rather than leaner and fitter.

The conversation covers the biological reasons women conserve fat in a calorie deficit, how female circadian rhythm differs from male circadian rhythm, and why eating within an hour of waking helps regulate cortisol and appetite hormones like ghrelin and peptide YY. Dr. Sims explains why fasted workouts can backfire for women, why front loading calories earlier in the day supports better metabolic outcomes, and why time restricted eating works with a woman's biology in ways that intermittent fasting often does not.

Guest links:

Dr. Stacy Sims

Dr. Stacy Sims (Facebook)

Dr. Stacy Sims (YouTube)

Dr. Stacy Sims (Instagram)

Stacy T. Sims, PhD (LinkedIn)

Dr. Stacy Sims Newsletter

Dr. Stacy Sims Microlearning Course

Books

“The New Perimenopause,” by Dr. Mary Claire Haver

“The New Menopause"⁠ by Dr. Mary Claire Haver

“Next Level: Your Guide to Kicking Ass, Feeling Great, and Crushing Goals Through Menopause and Beyond,” by Dr. Stacy Sims

“ROAR: How to Match Your Food and Fitness to Your Unique Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life,” by Dr. Stacy Sims