My 2.5 DS is fairly short for his age. He often fits into smaller clothes but I've noticed that his belly is pretty big. I know toddlers have big bellies, but when is it an issue? He's recently potty trained, but until then had the same size nappy for over 14 months so it's not like he's piling on pounds anywhere else. Just the belly - which gets bigger over the course of the day!
I don't monitor his food intake - he eats well some days, less so other days, but he has a good, healthy diet a lot of the time and some treats.