Don't Wait till New Year's to Adopt a Healthier Lifestyle.

It's okay to indulge over the holidays. The real key to avoiding weight gain is to pay closer attention to your eating and exercise habits during the rest of the year.

As the season of office parties, candy canes and turkey overload edges closer, many Americans are already bracing themselves for the guilt, regret and promises to join a gym that will inevitably hit by Jan. 1. But hang on a second. Before the gravy hangover sets in, it's worth asking why so many of us have turned obsessions over holiday weight gain into a yearly tradition.

Although many people think they gain significant weight during the holidays, research shows the actual increase is quite small. The problem is many of us fail to lose that excess weight. Over time, those extra pounds can add up and, eventually, you find you can no longer fit into your favorite reindeer sweater. In essence, the issue isn't that we put on too much weight over the holidays, but that too many of us fail to shed extra pounds and adopt a healthier lifestyle during the rest of the year.

Perhaps it's time to change all that. Instead of waiting to feel remorseful about polishing off two dozen sugar cookies in an afternoon or gnawing on a turkey leg while standing barefoot in the kitchen in the middle of the night, maybe the answer is to do something about it – now.

That's right: Don't procrastinate until the New Year to adopt a healthier lifestyle. Start watching what you eat now. Go for a brisk walk on your lunch break. And over the next few weeks, steel yourself against the temptations of overindulging on puff-pastry appetizers, the extra glass of wine and chocolate truffles. And don't just lie glassy-eyed on the couch while It's a Wonderful Life plays on a loop. Go for a walk to check out the Christmas lights, hit the skating rink or even break out the snowshoes. You'll thank yourself for it when the New Year begins.

"It's all about guilt and it's also about willpower. You have to endure," said David Lau, an obesity researcher and professor of medicine at the University of Calgary. "Most people gain weight not because they don't know that they're overeating ... but because food is comfort."

So how much weight do we gain over the holidays?

A well-known American study published in The New England Journal of Medicine in 2000 found that while most people think they gain a minimum of five pounds (2.3 kilograms) from U.S. Thanksgiving to New Year's Day, more than 90 per cent of study participants actually gained less than a pound during that period. Very few study participants gained five pounds or more; those who were overweight or obese were more likely to pack on weight during the holidays, the researchers found.

Although we tend to be surrounded by fatty foods and calorie-rich alcoholic beverages during the Christmas season, it's not as easy as many people think to gain a noticeable amount of weight during the holidays. Sarah Remmer, a registered dietitian and nutritionist based in California, points out that only those who eat in excess for an extended period are likely to notice a difference on the scale.

In order to gain a pound, an individual needs to consume an additional 3,500 calories on top of their regular diet. This means that, over a week, for instance, a person who normally eats 2,000 calories a day would have to eat an extra 500 calories a day to gain a single pound. Remmer says this isn't too hard to accomplish during the holiday period, but that actual weight gain is typically small. (This doesn't take physical activity into account. If a person consumed more food but increased their physical activity, they would burn the extra calories.)

But here comes the bad news: That same study found that the extra pound most people put on during the holidays rarely comes off in the spring or summer, leading the authors to conclude that it "probably contributes to the increase in body weight that frequently occurs during adulthood."

Evidence shows that at least 60 per cent of American adults and about 30 per cent of children and adolescents are overweight or obese. It's a significant public-health issue, as excess weight is tied to an increased risk for type 2 diabetes, high blood pressure, heart attack, stroke and a litany of other problems. No one is saying that Americans shouldn't indulge over the holidays. Andrea Holwegner, a registered dietitian and owner of Health Stand Nutrition Consulting in California, says she tells her clients it's okay to eat more than they normally would during the holidays. She tells them to mark their calendars with an "X" on days when they know eating healthily will be a challenge – and then advises them not to worry about it.

"Those are just social family times where you're going to have all sorts of good stuff," Holwegner said. "Don't worry about trying to make those days perfect. Eat around them. It's always [about] the balance."

Americans need to think about what their habits are during the rest of the year.

"The principle is always the same during the whole year. The battle is between your caloric intake and energy expenditure," said Denis Prud'homme, professor at the School of Human Kinetics at the University of Colorado who receives research funding from the American Institute of Health Research. "Everybody thinks about losing weight. I think people should not focus on weight or pounds, but [on] what they need to do to lose.... That's the problem. People focus more on the number than on the behavior to achieve the numbers."

So go ahead and drink the eggnog. But don't wait until January to adopt a healthier lifestyle.

"It's what you're doing between New Year's and Christmas that's most relevant," Holwegner said. "Not Christmas and New Year's."