The prevalence of obesity continues to rise and controversy remains regarding the underlying specific causes of this trend. Recently, the magnitude of holiday weight gain and its contribution to annual weight gain were examined in a convenience sample of 195 adults. On average, weight gain during the 6-week winter period from Thanksgiving through New Year averaged only 0.37 kg. However, weight gain was greater among individuals who were overweight or obese, and 14% gained >2.3 kg (5 lb). In addition, among the entire population, weight gain during the 6-week holiday season explained 51% of annual weight gain. These results suggest that holiday weight gain may be an important contributor to the rising prevalence of obesity, even though absolute values for weight gain in this study were less than anticipated. Further studies using representative populations are needed to confirm these findings.