Feeling Why am I Hungry After Sex is a common experience, and there are several physiological and psychological factors that may explain why this happens. Sexual activity can be physically demanding and involve a moderate amount of energy expenditure. Depending on the intensity and duration of the act, you may burn calories, similar to light to moderate physical exercise. After sex, your body may be craving calories to replenish energy stores. This hunger is the body’s way of signaling that it needs more fuel after a period of physical activity. After orgasm, levels of oxytocin and prolactin rise, which may contribute to a sense of contentment and relaxation, but your body might also feel the need to "recharge" by signaling hunger.