Sounds like he's not burning off more than he's taking in....stop training HIT and start doing some actual training, problem solved!
I dont train HIT....I tried it...and I didnt care for it. As for actual training.....here is my last chest workout:
Flat Dumbell Bench : 120x9, 105x9, 105x7
Incline Bench: 225x11, 225x7, 185x10
Body Master's Bench Machine: 235x8, 235x6
I know its shitty weight....but thats a general chest workout for me. I do an absolute 2sec negative on everything and I dont pause mid-set.