I eat much, I feel Hungry all the time but I lose wheight?

Someone ask me this question:
I feel hungry all the time, so I eat much, but I lose weight?


He eats a ton during the day, but he never gains weight. In fact, as of yesterday he'd dropped 10 pounds. The thing is, he doesn't exercise as regularly as he should and recently he's been eating a whole lot more than normal , So He was kind of worried about it. 
The sport which he practice both fitness and Taekwondo, but he had to stop due to the fact he had lime disease. Could this possibly be related? He has the thought that perhaps it's just transition from muscle to fat because he hasn't been working out as often, but wouldn't that mean he'd gain weight?

My Answer:

I think he just has a fast metabolism. When did he lose 10 pounds was it in a day or a week. Rapid weight lose can be caused by a number of things from a thyroid problem to diabetes. 
It's hard to say why he's losing weight despite the fact that he's eating more and exercising less. Muscle does not simply turn into fat. It is wrong to think that his muscle is transitioning to fat. Perhaps he is losing muscle, and gaining fat, but they do not transform into each other. Muscle is more dense than fat, and occupies less space. So, if he were losing muscle, this would explain his weight loss. There could be many reasons for his weight loss, and, if it persists, he should see a doctor. Lyme disease has nothing to do with it though.  I doubt it was the lyme disease if it was treated properly.