It's really sad seeing kids like that. Kids are naturally full of energy, they can eat tons of sugar and because they like running around so much, they come to no harm except rot their baby teeth. For them to get fat (not even 24 stone fat), they'd have to have been essentially caged (sit down, you can't go play with your friends) or sedated (ADHD drugs and similar). There will be a small number of children whose genes require them to be fed less, and of course there are disabilities, but looking around, that can't be the case for all the fat kids.