Carrots probably won't make you fat if all you eat is carrots. Buttery carrots--you might end up eating more butter than you'd eat as just butter--maybe more than if you had just butter and meat. It's funny that palatability/reward food science is fairly well accepted, but nobody acknowledges that you'd eat more apple pie or other pastry than you'd eat plain pie crust, fairly innocuous veggies like mushrooms or green peppers will have people eating more pizza, etc.