I personally don't care for the "diet" dog foods. What I like to do is just cut back the amount of food the dog is eating by a quarter cup or so every two weeks. I had to do this for Yogi when I recently switched his food. His new food has a much higher kcal than the old food so he did gain some weight but it is slowly coming off. Gunny also gained weight and I had to cut him back as well.