Why would you demand a negative thing for another group to counter a negative thing for one group? That makes no sense.

But also, “American children” has plenty of cultural material to build an image from. Probably some of it is obese and filled with junk food, but a good portion is most probably something else. In contrast, the only public photo material of palestinian children is either from adults carrying them away from some atrocity or adults giving them assault rifles and parading them for the cameras. In short, they seem to only exist as propaganda material.