oh man , I could go on and on about my Bella. She was 8lbs at 5 months, that is an extreme, but a concern. She got the diagnosis of Exocrine Pancreatic Insufficiency and within a month of medication, she gained twice her weight. I know this is a weird question.....how are his ? does he eat like he never eats?
If he is healthy has muscle tone and active, you most probably don't have to worry.