If you eat that "poison" then quitting it will drop your weight. But some people don't eat that "poison" and yet they still carry a lot of body fat. So it is good general advice but insufficient for people with a genetic predisposition to obesity. I for one eat mostly salad, never drink sodas and don't really like sweet things, usually skip breakfast, hunt rabbits most days on steep terrain (for exercise and dogfood)... and yet I sit at 220lbs.