Current findings on the relationship between excessive appetite for carbohydrate-rich foods and mood disorders may explain repetitive weight gain or the inability to lose weight among some obese individuals. Obese individuals who crave carbohydrates, exhibit positive changes in mood after carbohydrate intake; individuals suffering from Seasonal Affective Disorder experience a craving for carbohydrate-rich foods in association with their mood disturbances. Brain serotonin may be involved in these disorders of affect and appetite; thus therapies that mimic the effect of carbohydrate intake on the synthesis and release of this neurotransmitter may be useful in treating obesity arising from these causes.