I have a 20 month old BLM weighing about 62 lbs. He is very active and has rocket speed during training. He is fed Purina Pro Plan Sport 30/20 twice a day for a total of 3 1/2 cups. He is all muscle yet his ribs show. He is otherwise very healthy, up to date on all vaccinations and adult deworm. Will he fill out as he gets older ? Should I bump up his food intake? Should I back off on the training sessions? Should I add something to his diet? Maybe it isn't an issue and just his body style. Any suggestions?