When my son was growing up, I noticed he tended to gain weight when he was under a lot of emotional stress. Normally, he was pretty average in weight, but during particularly stressful times, he gained weight. When things got less stressful for him, he lost weight. With the kinds of social behavioral issues the children described are experiencing (and the possible problems that could be causing them, like ADD, bi-polar, etc.), it's possible that putting on weight is a mechanism for coping with stress. Personally, I don't think children are helped at all by being ridiculed for any reason, not that anyone on this thread would do such a thing to a child's face.