Overfeeding a puppy can result in various short-term and long-term health problems. To begin with, it can cause your puppy's stomach to become bloated and result in a condition called gastric dilation volvulus (GDV). GDV is a life-threatening condition that leads to a twisted stomach. Also, overeating can cause your pup to become obese, as well as undergo a growth spurt and develop skeletal problems.