To help conquer your compulsion for certain high-calorie foods this holiday season, divide them into smaller portions.

That's one way to control calories and help ward off unwanted pounds, according to a new study by University of Pennsylvania researchers.

The study looked at consumption of three popular snack foods offered in individual servings: Tootsie Rolls, M&M's and soft pretzels. The researchers, led by Penn psychology professor Paul Rozin, tested the effect of providing smaller and larger portions of each treat to see how it changed the number of calories that participants took in. Would they, for example, eat more of the smaller treats and fewer of the larger ones?

No matter what size treat was offered -- a small Tootsie Roll or one four times larger, a whole pretzel or half a pretzel, one small scoop of M&M's or a large scoop -- they ate just one, even when they were encouraged to consume more. So those who were offered larger servings of treats ate more than those offered smaller portions.

The findings "suggest that people see food as [discrete] 'units,' " says Andrew B. Geier, a doctoral student in experimental psychology and co-author of the study, which is slated to be published in the journal Psychological Science. "Whether you give them a six-inch sub or a nine-inch sub, a small plate or a large plate of food, one small scoop of M&M's or one large scoop, these 'units' are governing intake control of food."

Researchers call this "compulsion completion." Or as Penn State research nutritionist Liane Roe puts it: "If your mind sees a food as an entire whole, somehow you have this drive to finish it."

Capitalize on this phenomenon by cutting foods into smaller portions, Geier says, and you can cut calories without eliminating favorite holiday foods. "It can really make a big difference in calories at the end of the day," he says.

All of which is useful to keep in mind as we enter Week Three of the Lean Plate Club Holiday Challenge, which is designed to help you maintain your weight during the holiday season. There's no dieting involved, it's never too late to join the program, and the challenge can be of particular interest to overweight and obese people, who often add five pounds during this time of year, according to a study by National Institutes of Health researchers. Find additional tips, resources, charts to track your weight, activity and food in the free weekly Lean Plate Club e-mail newsletter and at www.leanplateclub.com.

Here are some other ways to help you get through the holidays without adding pounds:

Downsize your plates and serving utensils. That's what some cafeterias and restaurants do to help cut consumption. "People see plates as a 'unit' of food," Geier says. "So when food services want people to eat less, they give them seven-inch plates instead of nine-inch plates." Same goes for serving utensils. In an ongoing study, Geier has replaced the large scooper at his university's cafeteria ice cream vat with a smaller one. Result? Lowered consumption.

Motivate yourself with music -- especially if you're having trouble working out or staying with your workout routine. Overweight women who played their favorite tunes while exercising were more likely to stick with their exercise regimen over 24 weeks than women who skipped the music, according to findings recently presented at the annual meeting of the North American Association for the Study of Obesity. These results are consistent with others, including a study of obese children that found listening to music helped them walk farther on treadmills and one of elderly participants that found music improved the physical therapy experience.

Enlist your grocer as a sous chef. Save time by buying pre-sliced vegetables and fruit; pre-cut lean meat or boneless, skinless poultry; and shredded low-fat cheese. Yes, it costs a little more but often it's just pennies -- more than worth your time. For example, an eight-ounce package of sliced mushrooms might cost just 20 cents more than eight ounces of whole mushrooms. The added convenience could make the difference between cooking a healthful meal and stopping for high-calorie takeout.

Another option: Pick up a roasted chicken or two for dinner one night and make the leftovers into soup, tacos or a topping for pasta the next.

Fill your cookie jar. Not with cookies but with strips of paper that have an activity written on them. It could be wrapping presents, writing Christmas cards or holiday notes, taking a walk around the block, giving yourself a bubble bath, doing a few push-ups or calling a friend. When you feel hungry, reach into the cookie jar. Whatever you pull out, you do. It's one of the tricks that registered dietitian Marsha Hudnall of the Green Mountain Spa in Vermont has found helps her clients maintain their weight loss.

Join the Lean Plate Club online chat from 1 p.m. to 2 p.m. today at www.washingtonpost.com or e-mail Sally Squires at leanplateclub@washpost.com any time.