i dont really recomend that he do massive eating. I have tested it out some and found it to be harder to eat as many calories, not that hard for me cuz i like to eat a lot. The goal for him especially since he is lean, is make sure you get enough protein and all, but just eat. Then eat and eat some more. Then when you feel like you can’t eat anymore wait 2hrs and suck down a protein smoothie. Don’t be afraid to eat junk food either, its not ideal, but c’mon you haven’t gained ANY weight.