Spring is here at last, but are you holding on to the past — the weight you gained over this past winter, that is?

A new study suggests Americans probably gain about a pound during the winter holiday season, but this extra weight accumulates through the years and may be a major contributor to obesity later in life, according to researchers at the National Institute of Child Health and Human Development (NICHD) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

"These findings suggest developing ways to avoid holiday weight gain may be extremely important for preventing obesity and the diseases associated with it," said Dr. Duane Alexander, NICHD director.

Previous studies suggested Americans gain an average of 0.4 to 1.8 pounds each year during their adult lives, said Dr. Jack A. Yanovski, the study's principal investigator and head of NICHD's Unit on Growth and Obesity. It was unknown, however, if people gained weight at a steady rate throughout the year, or just at certain times, such as during the winter holiday season.

The researchers asked the volunteers about several factors that might influence weight change, such as stress, hunger, activity level, changes in smoking habits, or number of holiday parties they attended. The researchers found that only two factors influence weight gain: level of hunger and level of activity.

"Although an average holiday weight gain of less than a pound may seem unimportant, that weight was not lost over the remainder of the year," Yanovski said.

When 165 of the 195 study volunteers were weighed a year after the study began, they had not lost the extra weight gained during the holidays, and ended they year a pound-and-a-half heavier than they were the year before.

The knowledge that people actually accumulate a large proportion of their yearly weight gain over the winter holiday season may prove useful in treating overweight and obesity, the researchers added.

For additional information visit the National Institute of Diabetes and Digestive and Kidney Diseases' Web site, at: http://www.niddk.nih.gov, and be on the lookout for Wellness Junction articles highlighting ways to keep off the weight during holiday seasons.