Hormonal Shifts

• There is a stereotype that women often crave chocolate right before their menstrual cycle, which isn't entirely off base. When a woman's estrogen levels drop before their cycle, so do their serotonin levels, a chemical that helps people stay calm. Chocolate contains phenylethylamine, a chemical that can make some people feel happy and can offset these drops in natural hormone levels.

Need for Energy

• Chocolate also contains a chemical called theobromine. The human body reacts to this particular chemical much like it does to caffeine, which means some people may crave chocolate when they need an energy boost.

Psychological Associations

• Not all cravings for chocolate are a result of physical changes or a desire for the chemicals contained in the sweet. A professor of biological psychology from Bristol University deduced from his studies that many cravings for chocolate stem from people's associations of how it is a desirable, yet forbidden, treat. It is desirable because it is a sweet, tasty gift, but forbidden because we know we shouldn't eat too much of it.