How much food does a dog need to eat? Are there any guidelines about diet and how much food is needed?
Vet Susan McKay says: There are differences in how many calories are required by individual dogs. Some have higher metabolic rates, or are more active and can therefore eat relatively more food without putting on weight.
Those with lower metabolic rates may have to be fed much more meagrely if they are to avoid weight gain. There are feeding guidelines on packs of pet food but these are just indicators of the amount of food your dog requires and should be used as starting points only. If your dog is constantly leaving food and is maintaining, or even gaining weight, you are probably feeding too much and you need to scale back.
Over time you should be reassessing and adjusting the amount you feed to keep your dog in good body condition. That's why learning how to do body condition scoring or knowing a baseline weight is so important. If you intend to feed treats you should adjust the amount of food you give accordingly.