Research is discovering new ideas about how and why we, as a nation, are so overweight. The consequences of carrying extra pounds affect our long-term health and well-being in ways doctors and scientists are only beginning to understand. In a very short time, America has become a country of citizens packing on too many pounds. Fast food diets and lack of exercise are the main culprits, but researchers are puzzled by how fast each generation has added so much weight to our bodies.