Is this too much for a 5 month old?

If a baby was born at 32 weeks and weighed 4lbs 14oz, and is now 5 months and weighs 24lbs, would you say thats too big? its just my SIL feeds her 5 month old 10oz at feedings every 3 hours plus applesauce, mashed potatoes, all that and he looks SO fat. like really really fat. Is that too much weight?