I believe weight is something you just can't rush, kinda like height. My son (Just turned 16, 5'10, 150, middle infielder) works out with a reputable olympic and NFL combine trainer and his advice was simply eat a balenced diet, eat MORE and eat MORE often!!! We do the "Muscle Milk" shakes , but they are not a replacement for eating solid foods. The best advice he had was to eat 5-6 medium size meals throughout the day, emphasizing the final meal of the day (just before bed) to be quite large or supplimented with a shake. So far it seems to have worked, he put on about 15 lbs of muscle in 5-6 months.