//If you're using a commercial pet food, beware of the "feeding guidelines" on the bag or box. It lists different weights and the corresponding amount of food to feed your dog to maintain that weight, and should be used only as a rough guideline.
Many dogs are overweight because their families closely followed the directions on the label, which often indicates portion sizes that are too large. After all, the sooner the bag is empty, the sooner you will need to buy more food.//
above quote is from this website--