Day 23: Alternate Cocktails with Water

By alternating cocktails with water, “you’ll literally cut your calories in half,” says Susan Kleiner, Ph.D., R.D., author of The Powerfood Nutrition Plan. “Better still, you’ll pay less of a price the next morning.” Be especially wary of liquid calories in traditional drinks like eggnog, hot toddy, and punches. “You’re not going to feel full from them, so you can pack on a lot of extra calories and not even realize it,” says Jamie Cooper, Ph.D., an associate professor of food and nutrition at the University of Georgia. His advice: During the rounds where you do have an adult beverage, stick to low-calorie drinks such as light beer and vodka soda.

For more 31 Days of Fitness tips, check here for a new one every day in December.