At one point in our evolution, people who were heavier than average were prized as mates, clearly having access to food and resources. That is no longer true, and today obesity is instead a strong predictor of health problems; the person of normal weight is, on average, healthier than his or her overweight counterpart. All animals, including humans, choose partners partly (if subconsciously) on reproductive fitness: will this person be healthy enough to carry on my genes?