Fasting and Active Women: Why the Science Says “Fed is Better”
Fasting has been a hot topic for years. Some swear by it. Others say it’s not worth the hype.
But according to Dr. Stacy Sims, the conversation doesn’t need to be so polarizing — at least not for women who exercise regularly.
Her stance?
“Fasting simply doesn’t support active women.”
(For sedentary women, she notes, there may be some benefits.)
Why the Mismatch?
For decades, women have been given health and fitness advice based on male physiology. Training, weight loss, medical guidelines — most of it comes from research done on men. And fasting is no different.
Yes, research suggests fasting might work well for active men. But for active women? The science points the other way — and here’s why.
The Science Behind It
Women are naturally more efficient at conserving both fat and protein during fasting or prolonged exercise. When your brain senses you’re not getting nutrients, it produces fewer neuropeptides (chemical messengers made from amino acids). This triggers your body to hold onto energy stores even more tightly.
Add exercise stress into the mix, and additional hormonal changes occur — increasing your drive to eat and making it harder to meet your body’s needs.
If this pattern continues over time, the results can include:
-
Reduced thyroid activity
-
Disrupted menstrual cycles
-
Increased body fat despite eating less
This explains why women who start fasting alongside male partners often have a completely different experience:
-
Men: Lean out, train well, feel sharp
-
Women: Gain weight, feel anxious, struggle with energy and performance
What the Research Says
-
2021 Review: Eating before you train can lead to lower food intake and better appetite control for the rest of the day. Fasting, on the other hand, often leads to less movement and more hunger later.
-
2024 Female-Only Study: Exercising in a fed state improved both appetite control and blood sugar regulation.
What This Means for Empower Women
If you train in the morning, eat something first — especially if you’re following an Empower program. A small meal or snack before your session can support energy, performance, and recovery.
Because when it comes to active women, the science is clear:
Fed is better.
