[ServingGrace]

You mentioned less walks in the summer. Depending on his breed is there a place you could take him swimming? If not could you get him a backpack to carry around? The added weight would make each walk burn more calories.
I have always fed organic raw grass fed meat (whole processed rabbits) to my dogs so I'm not sure what the kibble amounts should be. But I agree with the previous poster that if they should eat three cups and are getting human food cut the three down too two. Using portions of food for rewards is great. With our herding dogs and hounds I would have a small cooler pouch with frozen chunks the size of an ice cube for training treats till they learned to be sensible and only run when working.