Make sure he is getting enough Carbs, cereal, whole grain bread, he needs some fats , protein ,if he is tired then he could be deficient in vitamins so give him a good multiple supplement with anti-oxidants Vit C and BComplex some fish oil also can be good .This should help with his energy level, if he looses weight and is fatigued I would suggest a check up at the Doctors to make sure nothing else is going on ...good Luck