The effect of the holiday season on body weight and composition in college students

Background: With the rapid increase in obesity rates, determining critical periods for weight gain and the effects of changes in fat mass is imperative. The purpose of this study was to examine changes in body weight and composition over the holiday season ( Thanksgiving through New Year's) in male and female college students. Methods: Subjects completed three visits: the first occurred within 2 weeks prior to Thanksgiving, the second occurred within 5 to 7 days following Thanksgiving, and the third occurred within 10 days following New Year's Day. A total of 82 healthy male and female college age subjects participated. Body composition by dual energy x-ray absorptiometry (DXA) was assessed at visits 1 and 3 while body weight was assessed at all three visits. Results: Average body weight remained relatively unchanged from pre-Thanksgiving to post-New Year's (71.3 +/- 14 kg vs. 71.2 +/- 15 kg; P = 0.71) and, in fact, a subset of normal weight subjects lost a significant amount of body weight. However, percent body fat (25.9 +/- 9 % fat vs. 27.0 +/- 9 % fat; P < 0.01) and fat mass ( 18.3 +/- 8 kg and 19.1 +/- 8 kg; P < 0.01) significantly increased from pre-Thanksgiving to post-New Year's while fat-free mass ( 48.7 +/- 12 kg and 48.3 +/- 11 kg; P = 0.08) was not significantly different than the post-New Year's. A significant positive relationship ( P < 0.001) between the change in BMI and percent fat, total fat mass, total fat free mass, and trunk fat mass for the pre-Thanksgiving and post-New Year's visits were found. The same significant positive relationships ( P < 0.001) were also observed between the change in body weight and percent fat, total fat mass, total fat free mass, and trunk fat mass. Conclusion: Despite the fact that body weight remained unchanged over the course of the holiday season, a significant increase in % body fat and fat mass was observed. With recent evidence showing marked morbidity and mortality to be associated with increased body fat ( particularly abdominal adiposity), results from this study suggest body weight alone may underestimate the potentially deleterious effects of the holiday season.