Some Americans believe they gain four to five pounds during the holiday season, but in reality it is closer to one pound. However, this extra weight accumulates over the years and likely is a major cause of obesity later in life.Discovering how to prevent holiday weight gain is important to preventing obesity and associated diseases such as diabetes, high blood pressure, coronary heart disease, some types of cancer and other serious health problems, according to Sandra Bastin, Extension food and nutrition specialist with the University of Kentucky College of Agriculture.“To keep from feeling deprived during the holidays, fix traditional favorites but eat smaller portions of them,” Bastin said. “Look for ways to reduce the calories in side dishes. For example, use low-fat soup in a green bean casserole and sugar and butter substitutes in candied sweet potatoes. Also, consider alternatives such as steamed green beans, mashed sweet potatoes, baked potatoes or unglazed carrots."It is not necessary to serve many high-calorie foods when entertaining at home. In fact, guests may appreciate lighter fare such as raw vegetables or fruits with low-fat dips and reduced-fat cheese and crackers. Replace fruit punch and eggnog with spiced tea, 100-percent juice spritzer, club soda or ice water with a lemon or lime slice. Offer fruit or vegetable juices instead of carbonated beverages.Bastin suggests taking along a small package of cut-up vegetables or fruits to curb your appetite when doing errands or shopping rather than eating in a mall food court or stopping at a fast-food restaurant. “Never skip meals all day to be able to go to a holiday party,” she said. “Instead, eat low-fat, nutritious meals and drink plenty of fluids all day. Before leaving for the party, drink a large glass of water and eat a snack like yogurt or whole-grain crackers with peanut butter. You may also offer to bring nutritious party foods such as lean meats, low-fat cheeses, fresh fruits or vegetables.”To reduce calories, yet still enjoy a holiday event, plan what and how much to eat beforehand.“Let other guests go before you in the food or buffet line so tempting, calorie-laden foods might be gone by the time you get to them,” Bastin said. “Put food on your plate instead of eating directly from the buffet or food tables. Focus first on healthy foods; then choose bite-sized samples of several desserts and appetizers rather than a whole piece of chocolate cake or plate of fried chicken pieces or meatballs. This will enable you to enjoy many different foods without overeating. To keep from nibbling on food without thinking about it, move away from the table after putting food on your plate.”Sit down and concentrate on conversation rather than food. Practice being a slow eater.Wait 20 to 30 minutes after eating to allow your brain to tell your stomach you have had enough to eat before going back for another helping of low-calorie food.To keep from feeling forced to eat foods offered to you, learn to politely say "no," while complimenting the host or hostess on how good everything tasted. Wearing clothing that feels just a little bit too tight may keep you from accepting a second or third helping.