Not all fat is the same: The GOOD kind of fat is what's called "brown fat," because it helps you LOSE weight. Fat people have less of it than thin people. Older people have less of it than younger people. Men have less of it than younger women.
It's actually is brown in color and it burns up calories as fast as you can ingest them. If scientists could find a pill that would increase our brown fat, obesity would be a thing of the past.
How to get more of it? One way is to get cold--brown fat seems to be turned on by cold weather because it sucks white fat out of the rest of our bodies in order fuel itself. Another way to get it is to exercise, which can turn white fat into brown fat.
In the January 25th edition of the New York Times, Gina Kolata quotes endocrinologist Andre Carpentier as saying, "We have proof that this tissue burns calories--yes, indeed it does. But what happens over the long term is unknown." It could be that more brown fat would make people hungrier, so they would eat more to compensate for the calories burned by their brown fat--and end up right where they started (or even FATTER).
In her famous diet book "What I Learned From the Fat Years," Anne Strieber (who developed this diet using scientific principles and lost 100 pounds) tells us how to eat, but she also emphasizes exercise, in her chapter titled "The Tyranny of the Body." You don't have join a gym or be athletic to be fit--she explains that WALKING is the best way to exercise--and it not only exercises the body, it's good for the brain!