Curbing your lunch?

So my brother is in the middle of his P90X commitment and I'm seeing results. No doubt about it. It's interesting how he's going beyond the workout, by cutting out drinking, watching his food intake and the supplements he takes throughout the day. Personally, I think he's doing more than I would do.

One day, I ate the last apple and he got so upset with me that he stopped talking to me for the entire day. I mean... really? WOW. The reason behind it is that through his research, the apple has the most amount of fiber and complex sugars, or the composition of the apple will curb how much you eat a half an hour later. Something like that. So his routine was to eat an apple 1/2 and hour before lunch and he would get full faster. I thought it was a genius idea, mainly because apples are cheaper than the full bar or the other bars. Therefore, if you want to cut back on lunch, eat an apple exactly 1/2 an hour before. It has worked for him. For me, I'm still testing it, so we'll see.