This time of year it's nearly impossible to avoid parties bulging with buffets of tasty food and drink. But all that indulging can have a downside: holiday weight gain.

The average person gains 1.7 pounds between Thanksgiving and New Year's, according to a 2009 study. Considering the average adult adds on 2.2 pounds annually, that means more than 75 percent of people's yearly weight gain occurs during the holidays. What's more, other research shows the extra weight put on now isn't lost during the following year.

But there are ways to avoid this trap. Try these simple strategies and you can still eat, drink, and be merry without ending up looking as plump as Santa Claus:

Check Consumer Reports' 2015 Holiday Guide for our picks of the best gifts, details on the latest deals, time-saving tips, and much more. And see our countdown calendar for top gift ideas for everyone on your list.

1. Be Realistic

In one holiday weight gain study, 15 percent of participants indicated they were trying to shed pounds between Thanksgiving and the new year. But they ended up gaining the same amount of weight as others who were not trying to slim down. A better plan is to aim put off weigh-loss efforts until after Jan. 1.

2. Hydrate

While rushing around shopping and preparing for guests it's easy to forget to drink plenty of water. Try to get in at least eight glasses a day. Your body easily confuses being hungry and being thirsty, so drinking water regularly will keep you from eating when what you really need is to drink.

3. Limit Your Alcohol Intake

Alcohol calories add up fast. A 12-ounce beer has 140 calories and a 5-ounce glass of wine has 100. Plus, having too many drinks lowers your inhibitions, so when you imbibe you’re likely to eat more. So stick to just a drink or two, or be the designated driver, and avoid alcohol altogether.

4. Choose Your Glass Wisely

A 2013 study found people pour 12 percent more wine into wider glasses than into more narrow glasses. (A standard 5-ounce pour might look like a puny amount in a large wine glass.) And sometimes they overpour white wines, such as chardonnay and pinot grigio, because the lack of contrast between the wine and the glass makes it harder to see when to stop.

5. Eat Slowly

Some research shows that slow eaters tend to eat less food. Try this: Swallow each mouthful before taking the next bite and chat with a table mate in between forkfuls.

6. Beware the Buffet

A bountiful buffet can be a challenge for many. "Think of a buffet as a menu in physical form," says Karen Collins, R.D., nutrition adviser to the American Institute for Cancer Research in Washington, D.C. "You wouldn't order one of everything." Scan the choices before you pick up a plate. Or take smaller portions of a variety of dishes.

7. Outsmart the Food Pushers

Pressure from hosts to eat beyond your fill is a common challenge at the holiday table. One way to keep from overstuffing yourself? Ask for seconds. Seriously! Just take small portions, says Brian Wansink, Ph.D., author of the book “Slim by Design: Mindless Eating Solutions for Everyday Life." It’s an easy way to flatter your host without expanding your waistline. Wansink has found that hosts recall who asked for second helpings but that they don’t notice the serving size.

8. Be Selective, Not Rigid

Don't declare all party food off-limits. It's a strategy that's bound to backfire: if you decide to deprive yourself of all treats, you may end up overindulging out of frustration and rebellion. Instead, be honest with yourself about what foods you're really looking forward to and enjoy those in moderate amounts; at the same time cut back on high-fat and calorie-bomb snacks and fillers you really can live without.

9. Don't Starve Yourself Before Holiday Events

Fasting beforehand may seem like a smart way to "save up" for the calories you'll consume, but showing up to a party ravenous is only likely to cause you to eat too much as soon as you walk in the door. Instead, take the edge off your hunger before you leave home by eating small, low-calorie meals. A snack, such as a slice of cheese or a yogurt, on the way to the party can help keep you in control as well.

10. Stay Active

Exercise is probably the first thing to fall off your to-do list during the holidays, but it's your best ally in the battle against holiday weight gain—as well as holiday stress and depression. Don't worry if you can't maintain your regular workout routine due to travel or other commitments. Simply challenge yourself to add some physical activity to your day. After a big meal, keep the conversation going while taking a stroll. Or excuse yourself for a solo walk (think of it as a perfect excuse to take a break from annoying relatives!).