I'm going to have to go against the quick dismissals.
I hate to think that fatasses can use this as an excuse to gorge. And skinny people who try this usually just don't eat enough.
I've been following a "warrior diet" style way of eating for a while (I hate that name by the way). Not in the strict sense, but I do enjoy eating light until after my workout in the afternoon and then eating a lot afterwards. It helps me focus on my workouts better.
For a while, I used to actually eat nothing in the mornings and then train sometime early/mid-day after a class. My strength went up, as did my weight.
I enjoy being a little hungry while I work out. It gives me more focus, makes me a little pissed off, and I know that I have to work my ass off before I can eat a lot.
Now, I eat a lot more meals but still keep them light until after my workout in the afternoon. Anything heavy in the morning/day makes me feel sluggish.
See how your friend feels on this. It's definitely not recommended for everyone, but if your friend is getting the results he wants following it the way he wants, don't argue with him. There are people out there who do well with this type of eating... just not many. Doesn't mean it's 100% wrong, though.