Fasting for Women: Help or Harm? What the Latest Science Reveals

Nadine Rücker
Jul 23, 2025
3 min read

Overview

Fasting, including intermittent fasting (IF) and calorie restriction, has been studied for its effects on women's health. Evidence suggests potential benefits for reproductive, metabolic, and mental health, but also highlights important risks and limitations—especially for women of reproductive age or with specific health conditions. Below is a synthesis of recent scientific findings.

A pink alarm clock on a plate symbolizes the role of timing in diet and nutrition. — Time for Mindful Eating

Potential Benefits of Fasting for Women

Reproductive Health

Fasting and calorie restriction can improve reproductive health, particularly in women with polycystic ovary syndrome (PCOS). Studies show that IF may decrease androgen markers (such as testosterone and free androgen index) and increase sex hormone-binding globulin (SHBG), especially when food is consumed earlier in the day^[1]^[2]. These hormonal changes can help regulate menstrual cycles, improve ovulation, and enhance fertility in women with PCOS^[1]^[2].
Weight loss of just 5–10% through moderate calorie reduction can significantly improve psychological, reproductive, and metabolic outcomes in overweight women with PCOS^[1].

Metabolic Health

IF has demonstrated cardioprotective effects, such as weight loss, reduced fat mass, lower blood pressure, and improved lipid profiles (decreased total cholesterol and LDL, increased HDL)^[1].
In postmenopausal, overweight, and obese women, IF has been shown to reduce markers of oxidative stress and inflammation, improve liver enzyme profiles, and potentially protect against metabolic syndrome and cardiovascular disease^[3].
Fasting may help align eating patterns with circadian rhythms, which could further benefit hormone regulation and metabolic health^[2].

Mental and Cellular Health

Some studies suggest fasting may improve mental health and cellular health, reduce inflammation, and optimize circadian rhythms, potentially contributing to increased longevity and reduced cancer risk^[1]^[4].

Risks and Considerations

Hormonal Sensitivity and Stress

Women of reproductive age are more sensitive to stressors like prolonged fasting and caloric restriction. IF can increase cortisol (a stress hormone), potentially leading to blood sugar dysregulation, increased insulin resistance, lean muscle loss, fatigue, and thyroid dysfunction^[4].
Caloric restriction from IF may cause loss of menstrual cycles and interfere with fertility in some women^[4].

Disordered Eating and Mental Health

IF may increase the risk of disordered eating, especially in women with a history of restrictive dieting or eating disorders. It can also negatively impact mental health, particularly in younger women^[4].

Safety and Sustainability

IF is not recommended or women who:

Have irregular or absent menstrual cycles
Experience thyroid issues
Have a history of disordered eating
Are under significant stress
Have blood sugar issues
Are not sleeping or eating enough^[4]

Timing and Practical Considerations

The benefits of IF on androgen markers and reproductive health are most pronounced when food is consumed earlier in the day (e.g., finishing eating by 4 pm)^[2].
Skipping breakfast and eating late into the evening may disrupt circadian rhythms and contribute to hormonal imbalances^[4]^[2].

Limitations of the Current Science

Many studies on fasting and women's health are preclinical or have small sample sizes^[1]^[2].
There is a lack of research on perimenopausal and postmenopausal women, and more studies are needed to confirm findings across different female populations^[2].

Summary

Fasting, particularly intermittent fasting, shows promise for improving reproductive and metabolic health in women, especially those with PCOS or metabolic syndrome. However, it carries risks—especially for women of reproductive age, those with a history of disordered eating, or underlying health conditions. Benefits appear strongest when eating is aligned with circadian rhythms (earlier in the day). Women considering fasting should do so under medical supervision and be attentive to their body's signals, ensuring adequate nutrition and avoiding excessive stress^[1]^[4]^[3]^[2].