> Isn't that fraught with survivorship bias? It is, but it's not a completely invalid starting point. Even better is to study people who were once fat, but los

> Isn't that fraught with survivorship bias? It is, but it's not a completely invalid starting point. Even better is to study people who were once fat, but lost weight and keep it off. This is what the National Weight Control Registry does. It's similar to studies that have tried to pin down why marriages fail. Most studies focus on what went wrong in failed marriages, but some of the most helpful suggestions have come from what people who stay married do. > My son and I are normal weight. My wife and daughter are overweight. Do your wife and daughter eat the same portions as you and your son? It's a common complaint of women, who are on average shorter than men and therefore need fewer calories, that they can't eat as much as their significant others.