reasons you're hungry

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The snowdrifts outside your door.
What makes you hungry: A hearty cassoulet sounds so much more appealing in the winter than a salad. Scientists go back and forth about why. Ira Ockene, MD, a professor of medicine at the University of Massachusetts Medical School, has said that our appetites are spurred by a primitive impulse to stockpile calories—as much as 86 extra per day, according to his research—for the cold days ahead (call it the chipmunk theory). Others say it's because we require more energy—i.e., calories—to maintain our body temperature of 98.6 degrees. Or it could just be that when your body temp drops, you crave the sugary, starchy foods that act like kindling to fuel your internal furnace.

What to do: Layer up before sitting down to a meal, especially at a restaurant (many keep the temps cool so you order a more robust well as an appetizer).