5 yo DS suddenly expressing worrying body image - anyone else?

[fairypangolin]

My otherwise very happy, healthy and athletic DS, who is not fat by any measure has started to say things to us about his body that are quite upsetting. He started first to point to his tummy and say he didn't like it because 'cool people have flat stomachs'. I explained that his tummy is rounded after he eats because he's 5 yrs old and doesn't have much space for the food to go. Then a few weeks later he told me he wanted to start going to the gym to work out and lift weights. Then today I was asking him why he didn't want to wear shorts despite the hot weather and he said he didn't want anyone to see his legs. When I asked why he pointed to his thigh and said 'because i don't like this fat'. He was quite shy and embarrassed about it.

I am horrified by him expressing these feelings. Neither me nor DH have body image problems beyond the norm and we have never been on a diet or spoken critically about our bodies in front of him. No one we know has done it either. He watches kids' telly and I think the 'cool=flat stomach' thing come from superhero cartoons, because they always have ridiculously ripped muscles. It would be one thing if it was just a joke but he really seemed upset about his legs and it is making him alter his behaviour.

Has anyone else experienced this? I think I would be more prepared if he were a girl but I am worried because I don't want this to become a theme in his life. I have reassured him every time that his body is just the way it is supposed to be, that he's not "fat" and his body does everything it should but I am bothered because it has come up several times now in several different ways.

I think that this will have come from real people eg other kids at school rather than cartoon heroes. Do any of his friends have older siblings? Is he getting bullied or name called?
Perhaps it would be worth speaking to his teacher about what he's said and getting them to do some work or talk about their bodies and what's normal and natural.
I agree it sounds alarming but keep him talking and keep reassuring him.

hilly thank you so much - I asked him tonight whether someone told him he had fat legs and he said a boy in Year 1 did last autumn when he last wore shorts. I told him that he didn't have fat legs, the boy was just teasing him. He was a bit sceptical but cheered up when I said that I guaranteed him that boys with skinny legs would be jealous of his strong legs (he is quite naturally muscular, like a swimmer, always has been). So I am hoping that will put that particular to worry to rest. I guess though it is something I will always have to watch out for with him, he is very self-aware self-critical child anyway. It just breaks my heart when I think he is perfect but I suppose all parents feel that way!