Hello dear, thanks for sharing your concerns. The problem your friend is facing is could be due to many reasons. Maybe his body parameters aren't normal, maybe his metabolism is very fast that whatever he is eating is digested quickly leaving nothing for the growth, maybe he is eating very less. He needs to have a daily calories intake between his BMR and TEE, and gradually increase it every week for a good amount of period to get the desired body weight and shape. unfortunately he is not having that right now. need not to worry, please share your contact details on my facebook page or visit my website www,dietitianshreya.com