Not knowing his work load or consistency to his training the term can be misleading. I have known guys to say the same thing. Usually they have been overtraining and not eating properly.
Most have been sticking with a routine to long with no changes or change every other week! He should get a good routine to try say 5/3/1 or 5x5 and stick with the program as it is laid out. Also he may try extra calories(good ones) before bed. Like a good protein shake. Also he needs a good supplement plan. Start with the basics: Creatine, multi-vitamin, pre-workout drink ect.... Good luck!!!