Dog Food overfeeding Incident

My mother told me she caught my brother over feeding their dog. Apparently when we confronted him claims that the dog looks starving. Their dog is a hound and loves food but of course I looks like it looking for food because it loves it. Our vet said he is at average weight not fat nor skinny. We been feeding him that same about every day 2 cups of kibble in the morning and 1 cup in the evening. He gets a treat before bed.
I told my brother there is a reason why on the package they put the amount of how much per weight of dog / or what the vet recommends. If we were starving him I’m pretty sure us and other could tell. I told him that obesity does kill dog it didn’t believe me and I told him to google it.