Why might a person eat fewer servings than recommended by the mypyramid and still gain an unhealthy amount of weight?

I think the person got some "fats" in there serving and havent burn it through exercising so its stored in the body as body fat which will make the person gain weight.

one time i was looking at my neighbors screen door to see if the door was open i was squinting like a fool for 10 minutes before realizing he was starring back i then died from embarrassment and am now typing this from the ghost world