weight gain/diet/nutrition

My son is 11 yrs old he is 5'3 weights 159lbs he excercise 1hr a day 4 days a week works out with a personal trainer, plays football, basketball and baseball practice on top of the gym time and we really police what he eats and yet he is gaining weight instead of loosing it. Im not quite sure what we are doing wrong feeding him lots of baked chxn and fruits no soft drinks but lots of crystal light which is 5calor. drink mix with 16oz water. He is frustrated and so am I. We have spoke with family Dr. he does not seem to think it is a medical condition.

[Renee Radenberg]

When you work out and build lean body muscle, you gain weight because muscle weights more then fat. Your son exercises numerous hours for an 11 year old plus he plays sports on top of the exercise. I recommend you put the scale away and get a measuring tape. Just have him measure his chest, waist, and thighs. You want to see the chest / thighs build up and the waist go down. If he does not want to measure, then a good indication that he has weight loss (but the scale says differently) is that his clothes are loose fitting more then before. If that is not the case, then have his MD run tests and check him out.