There are many theories about why the obesity epidemic arose. Research during the molecular genetics boom years suggested a plausible explanation: genes that once protected us from starvation during our hunter-gatherer evolutionary history - enabling us to store energy as fat when food was limited - might conspire to create obesity against the modern backdrop of readily available processed foods and sedentary lifestyles. Yet, if this is the case then why do so many maintain a normal healthy weight in the face of this ‘onslaught of plenty’?