The Scientist: Lisa C. Cohn, M.M.Sc., M.Ed., R.D., is the President of Park Avenue Nutrition and a licensed, registered dietitian who practices in Manhattan.

The Answer: Actually, your metabolism speeds up when it’s cold out! Keeping warm uses up a lot of energy, which burns more calories, which means a higher metabolic rate. So if you stick to your regular exercise routine and eat right all year round, you should actually lose weight in winter, especially if you spend time outside.

The reality, however, usually looks very different. Many people gain weight between Thanksgiving and New Years, and those who do put on an average of seven pounds.

The obvious culprit is all that party-time feasting and drinking, not to mention the emotional eating we often succumb to when we spend a lot of time around our families. Plus, we often throw our exercise routines out the window during the holidays.

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Then there’s the travel and the shopping, last minute wrapping and looming credit card bills. Holiday stress increases our levels of the hormone cortisol, which stimulates a rush of glucose from cells into your bloodstream. Depleted of its stores, your body craves food—NOW! Suddenly famished, we tend to skip the healthy sources of energy—a peanut butter or turkey sandwich, say—and grab something caffeinated (a latte) or sugary (a muffin) for a quick energy boost.

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In order to take advantage of your amped-up winter metabolism, maintain a healthy sleeping, eating and workout schedule all year round, not just in the fall, spring and summer. Pack some good food when you’re on the run and don’t be afraid of the cold. It could be the secret to a wintry slim-down.

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