Tell me, science, why does a gay man like me care so much about his fitness? "The drive among women and homosexual men to lose weight comes more from a competitive instinct than a personal one, new research suggests. The study, published in the journal Evolution and Human Behaviour, found that a natural competitive instinct forces people to compare themselves with those who are more successful than them. And in a society that equates thinness with youthfulness and attractiveness, competing against someone successful often means losing weight. Researcher Norman Li told New Scientist magazine that the effect is likely evolutionary since western civilizations tend to gain weight as they age." Finally, we can stop blaming magazines.