Can fasting stop menstrual cycles?

Yes, significant calorie restriction can impact menstrual cycles. Dr. Rhonda Patrick discusses how in animal studies, a 40% calorie restriction led to the cessation of menstrual cycles in female rats over several months. In humans, the effect likely depends on the degree of calorie restriction combined with other factors like physical activity level. 1

Intermittent fasting, such as time-restricted eating or fasting for 24-48 hours, typically does not affect menstrual cycles significantly in most women unless they are also severely restricting calories or engaging in high levels of physical activity. 1

It's important to consider individual responses to fasting and consult with a healthcare provider when making significant changes to dietary habits that may impact hormonal balance and reproductive health.