The impact of fasting and other diets on menstruation and overall reproductive health is minimal. Hence, whether fasting affects the menstruation cycle or not isn't conclusive. However,  studies say that diet restriction may impact the female reproductive organ. For example, the long duration of fasting affects the brain's hypothalamus, which is responsible for regulating hormones like oestrogen, which in turn regulates menstruation. Similarly, studies have also confirmed that calorie restriction lowers the level of progesterone, which again reduces the chances of ovulation.