Are you overeating? It could be because you are stressed, says a new study.

The relationship between diet, psychological stress and social and environmental factors is complex. Emory University researchers sought to determine whether individuals exposed to stress eat too much calorie-rich foods.

They studied the feeding patterns of female rhesus macaques, which are organised by a dominance hierarchy that maintains group stability through continual harassment and threat of aggression.

Such a structure is a constant psychological stress to subordinates, said Mark Wilson, who led the study.

During the study, female macaques were given access to a sweet but low-fat diet and a high-fat diet for 21 days each. For a 21-day period between each test diet, the group was given standard monkey chow.