The present invention relates to compositions comprising one or more anthraquinones for use in the treatment of obesity and related metabolic and liver disease. More particularly it relates to a plant extract fraction rich in anthraquinones including both anthraquinone glycosides and anthraquinone aglycones obtainable from a member of the Leguminosae family, more particularly Cassia seeds. It also relates to a method of obtaining a plant extract fraction rich in anthraquinones.