Hunger and fatigue can feel a lot alike, and it can sometimes be hard to tell the difference when you're trying to slog through a boring, late-afternoon meeting. In hunger and in tiredness, your body is simply crying out for some kind of quick energy boost (it's like the food equivalent of a yawn, which brings a fast wallop of reviving oxygen to the brain when you're sleepy).
It's common for people, in this weakened state, to misinterpret fatigue as hunger, so they eat something, even if they didn't really need it nutritionally. So, before you have that emergency snack, consider the idea that you might be worn out instead of hungry. You might consider taking a power nap of 10 to 20 minutes, or, at the very least, take a time-out: Sit down, close your eyes and relax for a minute. Barring that, the great sleep substitute -- caffeine -- can help to keep false hunger pangs at bay. Sure, a cup of coffee or a sugar-free energy drink can wake you up, but caffeine can also quench hunger, at least for an hour or two.