The bag of food typically tells you approximately how much food to feed a dog. Depending on the level of exercise they are getting, you adjust to be on the low end, high end, … or somewhere in the middle. I feed my 6 month old Labrador 4 cups of Blue Buffalo a day, in addition to raw chicken and occasionally fish.abs loose weight fast, incidentally, so I would recommend feeding 2 cups. If you notice weight going on by the tests I mentioned above after a week or so, then start reducing the quantity by 1/4 cup at a time for a week each time.