There is no such thing as a gene that makes it impossible not to be obese. We are not powerless slaves to our genes. Indeed, we have a great gene pool, honed by five hundred million years of evolution. Our Paleolithic ancestors trekked for miles in search of the right kind of wood for making spears, they used those spears to take down wild horses and woolly rhinoceroses, they banged out stone tools and used them to cut up their kills, and then they shouldered the meat and carried it home. All this took tremendous amounts of energy. The lesson is clear: Our bodies evolved to be used. If you can't fit into your jeans, don't blame your genes.