Nutrition and metabolism are closely linked with reproductive health. Several reproductive disorders have been linked to malnutrition, diabetes, and obesity. Furthermore, fasting in numerous species can result in decreased fertility. New work from a Carnegie team focuses on the accumulation of triglyceride and a certain kind of steroids called sterols during the development of immature egg cells. The researchers were able to identify an insect steroid hormone that is crucial to both lipid metabolism and egg production in fruit flies.