Fat and fatigue

This on the news:

A study published on Monday found that people who sleep less tend to be fat, and experts said it's time find if more sleep will fight obesity.

All I know is that when I'm underslept (and what working mother of small children isn't?), I eat to compensate. And the more fat and sugar, the more comforting and, in the short term, energizing. So I wonder if sleep releases some magic chemical in a body that helps weight control, or if food is a logical antidote to fatigue.