Thanks for your response. I hadn't heard of Body Beast...but, I think we'll try P90X since we've already bought it. I'll have to add an additional 500 calories to his meals to help him gain, on top of the supplelments. Junk food isn't the problem, we eat very healthy which is why he doesn't gain weight!

lots of fruit, greek yogurt, lean meats, etc. The trick is to give him more calorie-dense nutritious foods...and more calories overall. He normally eats about 1500 per day...less than he should. Thanks again.