Why am I Hungry After Sex is a common experience, and it can be attributed to several factors related to physiology, energy expenditure, and hormonal changes that occur during and after sexual activity. Sex can be a physically demanding activity, and depending on the duration, intensity, and physical effort involved, it can burn a significant amount of calories. The more intense the session, the more energy your body uses. Afterward, your body may crave food as a way to replenish the energy spent.