The season of overindulgence starts Thursday when Americans traditionally sit down to gorge on turkey, stuffing, gravy, buttered green beans, sweet potatoes and pumpkin pie topped with whipped cream -- a Thanksgiving feast guaranteed to ruin waistlines and fatten thighs.

In the 39 days from Thanksgiving to New Year's Day, the average person is likely to gain between five and 10 pounds, according to Yvonne Bronner, associate professor of clinical nutrition at Howard University. So much for that fantasy of slinking around in a bikini in Barbados in February.

The standard approach to the holidays is to eat and drink like crazy and worry about dieting in January when it's time to make those short-lived New Year's resolutions.

"Few people are going to go on a weight loss program during the holidays," said Janet Zalman, director of the Nutrition Connection in Rockville, which offers nutrition counseling. "The real key is surviving without gaining any weight."

One answer for dieters and health-conscious individuals who wouldn't mind a second glass of wine or a few extra hors d'oeuvres is to increase the level of physical activity.

"Exercise not only burns off calories but helps you control your appetite," said Tracy Smyth, director of the BodyLine Exercise Studio & Boutique in Bethesda. This is the sixth year that Smyth has offered "guilt buster" aerobics classes on Thanksgiving Day. The classes have grown in popularity, said Smyth, because people think that if they exercise in the morning, they won't eat as much throughout the day.

A typical Thanksgiving dinner has 1,900 to 3,000 calories or more, according to nutrition experts. Howard's Bronner said that people are likely to eat about 500 calories more on Thanksgiving than they would during a regular meal.

For a person weighing 137 pounds, working off 500 calories would require one hour and 40 minutes of walking, 59 minutes of jogging at 11 minutes per mile or one hour and three minutes of swimming at a slow pace. A 176-pound person would have to walk for one hour and 18 minutes, swim for 49 minutes or run for 45 minutes.

A more reasonable approach would be to cut back on the calories and only take a one-hour walk after eating, said Bronner. After all, who feels like seriously exercising after wolfing down a huge meal?

To cut back on the calories, the Nutrition Connection's Zalman suggests:

Stuffing a turkey with whole-wheat bread and no fat.

Making a non-sugar cranberry sauce with apples, oranges and strawberries.

Eating very few appetizers and starting out with club soda before drinking an alcoholic beverage.