I am trying to make a diet for my grandson. I want to figure it out by fat, carbohydrate and protein grams. He has just turned 9 and is moderately athletic. I need to know how many calories he should have for his age and height. I need to know how many calories he should eat for him to loose weight. His doctor has prescribed a 3,000 calorie diet, but I think it's too much. He also has not given me his diet in grams. It's hard to measure foods without knowing how many grams he needs as all foods from the grocery labels are in grams. Is there anyone that can help me figure this out?