Stress is OK in small doses — it's our body's natural response to a threat. But if you feel perpetually like Andie trying to get Miranda's twins the unreleased Harry Potter novel in The Devil Wears Prada, it can have negative consequences on your body and mind. One of these side effects: weight gain. We talked to Dr. Charlie Seltzer, a physician board-certified in obesity medicine, to see how, exactly, stress can make you gain weight.