Chocolate also is the perfect mix of sugar and fat to turn on almost every appetite-triggering nerve chemical in the brain. The sugar in chocolate sparks the release of a nerve chemical called serotonin and might lower another nerve chemical called NPY; the end result is a sense of well-being. The sweet taste also releases endorphins in the brain, giving us an immediate euphoric rush. The fat in chocolate enhances flavor and aroma and satisfies another nerve chemical called galanin, thus curbing our cravings for fat.

That's just the tip of the iceberg when it comes to nerve-tingling chemicals. Chocolate contains theobromine and caffeine, compounds that provide a mental boost, and phenylethylamine, or PEA, which stimulates the nervous system, increases blood pressure and heart rate, and is suspected to produce similar feelings experienced when a person is "in love." Even the aroma of chocolate could affect brain chemistry. Finally, chocolate contains a substance called anandamide that mimics the effects of marijuana and boosts the pleasure you get when you eat chocolate.