This year, the key to a holiday season without added pounds could be a four-letter word: plan.

Members of the National Weight Control Registry - several thousand “successful losers” who have shed at least 30 pounds and kept it off for at least three years - plan ahead to avoid the holiday temptations that could sabotage their weight maintenance efforts.

“They seem to be good at anticipating where there will be problems,” says Rena Wing, registry co-founder and a Brown University professor of psychiatry and human behavior. 

“They think through what makes this holiday period hard for them.”

What else helps prevent holiday weight gain? Portion control. A recent two-year study of 600 overweight, middle-aged people compared five habits: eating more fruit and vegetables; reducing dietary fat; increasing lifestyle exercise such as taking the stairs; boosting trips to the gym and other planned exercise; and limiting portions.

“Portion control had the strongest relationship with weight loss and maintenance,” says the study’s lead author, Everett E. Logue, director of the Summa Health System’s Family Practice Clinical Research Center in Akron, Ohio. “You can have your cake and eat it too, you just can’t have much of that cake.”

With Thanksgiving behind us, here are some ideas for the next few weeks.

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Look back to see ahead

You already know from past holidays what your weak moments are likely to be. Is it the tempting holiday treats around the office? Plan now to have something healthful to eat at your desk. The stress of family gatherings? Get the gang moving - skiing, ice skating, hiking, touch football, Frisbee, even dancing. Holiday baking? Consider what Diane Lending of Harrisonburg, Va., does. Lending, who has shed 50-plus pounds and maintained that loss for two years, gives away most of what she bakes but allows herself one Christmas cookie a day.
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Veg out

Not on the couch, but on your plate. Most adults fall far short of the seven to nine servings aday of vegetables and fruit recommended by the National Cancer Institute.

Fruit and vegetables are low in calories, packed with nutrients and rich in fiber, which helps you feel full and stay “regular.”

UCLA’s Bowerman sips a 12-ounce can of V-8 as a way to keep holiday calories at bay. “Nutritionally, it’s a huge boost,” she notes. “Plus, it’s filling and only has 70 calories.”

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Make it hot

Reach for a comforting cup of low-fat or sugar-free hot cocoa when you get the urge to attack the holiday cookies or pumpkin pie. Sipping anything hot “will slow you down, because it takes a while to drink,” says Susan Bowerman, assistant director of the Center for Human Nutrition at UCLA. Plus, the liquid’s volume helps you feel fuller with fewer calories. The cocoa also packs some calcium. Also try hot tea, coffee or broth-based soup.

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Pack a lunch

It’s an effective way to control calories, portions and costs. Can’t pack every day? Pack a couple times this week - and while you’re at it, plan your next meal to stay a step ahead.

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Pick up frozen meals

They’re convenient and “calorically, you know what you’re getting,” says Bowerman, who suggests saving the plates from the prepackaged meals to use for easy portion control. Just read the labels carefully.

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Make time to be active

Whether it’s taking the stairs, parking at the far side of the mall, getting up a little early for a workout or just dancing instead of eating at the holiday party, physical activity will help you burn calories, manage stress and improve sleep. All of which helps to keep the scale steady.