Don't beat yourself up about indulging in a brownie or two when feeling down in the dumps. Multiple studies have revealed that chocolate (gasp!) is actually healthy in moderation. Although it's still high in calories, chocolate contains a myriad of beneficial nutrients that help regulate mood. The sugar that gives chocolate its rich taste helps increase serotonin levels, while the fat content releases mood-elevating endorphins [source: Carper]. Top it off with the stimulating effects of caffeine and antioxidant levels higher than even berries, and chocolate becomes a heavyweight mood-influencer. To avoid paying the price in the waistline area, however, indulge in just one or two pieces each day of the dark variety, which is more heart-healthy than milk chocolate.