“Carbohydrates set off a series of chemical reactions that ultimately lead to a boost in brain serotonin,” says Judith Wurtman, Ph.D., the former director of the Research Program in Women’s Health at the Massachusetts Institute of Technology Clinical Research Center. The higher the levels of serotonin, the more content you feel (at least temporarily). No wonder cutting out carbs can make you grumpy: A 2009 study from the Commonwealth Scientific and Industrial Research Organization, in Adelaide, Australia, found that low-carbohydrate dieters registered the lowest moods.

Source: http://www.cnn.com/2012/10/03/living/real-simple-emotional-eating/index.html