FALL 2000

Holiday Weight Gain May Contribute to Overweight and Obesity

While Americans gain much less weight over the winter holidays than is commonly believed, the weight they do gain may be a major contributor to the increase in body weight that often occurs during adulthood, according to a study from the National Institutes of Health (NIH). Cumulative holiday weight gain may be particularly problematic for those who are already overweight or obese.

Studies relying on self-reports show that most people believe they gain 5 pounds or more during the winter holiday period from Thanksgiving to New Year's Day. Researchers from the National Institute of Child Health and Human Development (NICHD) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducted a literature review and found no clinical evidence to support this conclusion. To determine actual seasonal weight changes, the researchers measured weight in a convenience sample of 195 adults from September through March, with follow-up measurements of 165 subjects in June and September/October. Their results appear in the March 23, 2000, issue of the New England Journal of Medicine.

Mean (+SE) Weight Change in 195 Subjects

The research team, headed by Jack A. Yanovski, M.D., Ph.D., head of NICHD's Unit on Growth and Obesity, recruited study subjects from the NIH campus and surrounding area in Bethesda, Maryland. The group was racially and socioeconomically diverse, and ranged in age from 19 to 82. Fifty-one percent were women. The prevalence of overweight and obesity in study participants was similar to prevalence rates in the U.S. adult population, with 27 percent of participants having a body mass index (BMI) between 25 and 29.9, and 21 percent with a BMI of 30 or above.

Participants' average net weight gain between September and March was 1.06 pounds, with 75 percent of that gain (0.8 pound) occurring during the holiday period from mid-November to mid-January. For the 165 participants who returned in June and September or October, the average weight gain for the full year was 1.36 pounds, leading researchers to conclude that weight gained during the winter holidays is not lost during the spring and summer months.

"Because losing weight is so difficult, it is important to learn when and why people gain weight so that effective strategies to prevent obesity can be developed," explained study co-author Susan Z. Yanovski, M.D., Executive Director of NIDDK's National Task Force on Prevention and Treatment of Obesity. The researchers explored possible reasons for holiday weight gain, including changes in perceived levels of stress, hunger, or activity; changes in smoking habits; the presence of seasonal affective disorder (SAD); and the number of parties attended. Only changes in activity and in hunger were related to changes in weight. Those who reported being much less hungry or much more active during the holiday period had the least weight gain, and some even lost weight. Conversely, those who reported increased hunger or decreased activity gained the most weight.

Participants who had a major holiday weight gain, defined as 5 pounds or more, were more likely to be overweight or obese than those who gained less. "Such weight gain may be clinically important, particularly for those already at risk for obesity related conditions," the researchers wrote. Weight gain during adulthood is a risk factor for type 2 diabetes, cardiovascular disease, and other conditions.

The researchers concluded that promotion of weight stability during the fall and winter months may prove to be a useful strategy for preventing the often substantial and potentially dangerous weight gain that occurs during adulthood. The finding that participants who reported more physical activity had less weight gain points to the need for further research into increased physical activity as a method for preventing holiday weight gain among persons at risk.

Reprints of the article are available through
Dr. Jack A. Yanovski at the
National Institutes of Health
Building 10, Room 10N262
10 Center Drive, MSC 1862
Bethesda, MD 20892-1862
and at www.nejm.org.