The reason for feeling very hungry on the period is mainly due to hormonal changes in the menstrual cycle. During the luteal phase (the days leading up to and the first few days of bleeding), progesterone levels rise and become dominant while estrogen levels decline. Progesterone stimulates appetite and increases food cravings, especially for carbohydrates and sweets. Estrogen, which can suppress appetite, drops during this time, contributing to increased hunger. Hormonal fluctuations also influence hunger-regulating hormones like ghrelin (which increases appetite) and leptin (which signals fullness), causing changes in how hungry or full a person feels. Additionally, metabolic rate slightly increases during the period because the body is using energy to shed the uterine lining, leading to a higher energy demand. This combined with mood swings, irritability, and cravings results in feeling hungrier than usual. Nutrient needs may also increase, and cravings might reflect the body's desire to replenish certain nutrients like magnesium or iron.
In summary, it is normal and common to feel more hungry on the period due to the complex interplay of hormones and energy needs during the menstrual cycle.