It sounds like they may be over fed. The rule of thumb is 10% up to a max of 20% of body weight. So for a 5 # kid, that is 5x16 = 80 x .10 = 8 ounces total for a 24 hour period . 20% would be 16 ounces - so 4 ounces. Make sure tummies are flat and not poochy. What are you feeding them?