100 lbs in three months is ~1lb/day, thus a deficiency of 3500Cal/day. His maintenance intake would have been 4300Cals/day. That seems insanely high - what was his weight?
He started north of 275 lbs if I remember. He was working out 3x a day. There are lots of videos out there about it. He was also overweight when he started, and he was going into hell week (military) so the first n lbs of weight would come off “easy”.