Now he's discouraged

The strange thing is, the doctor told him that he must have been eating around 5000 calories a day to maintain his current weight. I know what he eats and there is NO WAY he's eating that much in a day. He works odd shifts and sleeps at different times every week and really doesn't have time to sit and munch all day. On the weekends he might eat pizza or wings but I would still guess that he's staying around the 3000 calories, even on those days.
Since he started calorie counting, he really isn't eating much less, but he's eating more LOW FAT cheese or low cal breads....and even without changing his diet too drastically, he's staying around 2000 a day.
So, how is he maintaining his weight at that level, and why isn't he losing??

