I see a great answer for the baby not gaining weight. Is this also true in case of 8-9 yr old kids? My grandson does not gain weight despite eating lot of sugar, syrup etc. Of course, he does have lots of energy over the day/eve. He plays soccer and other games as long as you let him play without ever saying he is tired. But, he does not feel hungry after normal 4-5 hrs or more. He does not gain weight, as thin as one can think off, does not grow tall like his piers etc. We need to push him all the time to eat food.