The most important function of adipose tissue is its ability to store and release fat during periods of feeding and fasting. This allows food intake to be intermittent, freeing up time for other activities, and provides a life-saving buffer against protracted periods of famine. That humans are capable of surviving months of total starvation reflects the awesome storage capacity and survival advantage of adipose tissue. However, modern times with the abundance of food and decreased opportunity for physical activity have exposed a significant disadvantage to energy storage in adipose tissue, namely obesity, with its associated morbidities of heart disease, non-insulin-dependent diabetes mellitus (NIDDM) and high blood pressure. With this in mind, there has been intense interest in elucidating the mechanisms controlling adipose tissue development. Three recent papers in the October issue of Molecular Cell highlight the critical role played by PPARγ (peroxisome proliferator-activated receptor-γ) in this process (