The strategy of putting in a few more hours of exercise to offset some of those thanksgiving calories, may not keep off holiday pounds, according to a recent study.

Researchers followed 150 men and women between the ages of 18 and 65 for six weeks between the thanksgiving and New Year's celebrations. Based on the study, they found that exercise had no significant impact on weight gain.

Half of the participants in the study reported being serious, regular exercisers. On average, they said, they worked up a sweat almost five hours each week, nearly double the amount of moderate physical activity recommended by the American Heart Association. The other half copped to being couch potatoes.

Researchers weighed and measured each person to calculate their body mass index before and after the holidays. They also gauged their percentage of body fat and took their blood pressure.

They found that from mid-November to early January, people gain an average of one-and-half pounds. Men gained slightly more, around two pounds each, while women gained a little less, about a pound apiece.

People who were obese or overweight at the start of the study had the biggest increases in weight. They also had significant rise in their percentage of body fat.

Although, a pound or two may not sound so bad, but studies have found that on average, people gain about two pounds each year. It's called weight creep. And studies have found that once most people put it on, they never take it off.

When calculated, 10 years of small annual increases is an additional 20 pounds of fat. Researcher Jamie Cooper, an assistant professor of nutritional science at Texas Tech University in Lubbock, Texas, told HealthDay that this means holiday weight gain could be a more important factor in the obesity epidemic than many people realize.

Exercise had no significant impact on holiday weight gain. Researchers aren't entirely sure why exercise has no significant impact on holiday weight, but Cooper said she believes it could have something to do with people eating far more calories than they could burn off.

"If you think about going for a run, if you run for 30 minutes and you run three miles during that time, you burn about 300 calories. Well, one piece of pumpkin pie without anything on it is about 300 calories," Cooper told HealthDay. "So, it's really easy to eat all those calories that you burn during exercise and then some."

Exercise also boosts appetite, which can lead to even more overeating.

According to this study, there is no substitute for moderation during the holidays, a time when foods are much more likely to be loaded with fat and sugar and hidden calories.