Ordering an entrée full of hot peppers seems like a fine idea, but as soon as that first bite hits your mouth, the beads of sweat will begin to form. Your brain is actually reacting to the capsaicin (what makes those peppers hot) -- it thinks your body needs to cool down, so it puts your sweat glands to work. Not everyone has the same reaction to spicy food, though. "Know what triggers you to sweat," says Dr. Lyster. "And then maybe eat less of, or avoid, certain foods."