A prospective study of holiday weight gain

Background: It is commonly asserted that the average American gains 5 lb (2 .3 kg) or more over the holiday period between Thanksgiving and New Year's Day, yet few data support this statement. Methods: To estimate actual holiday-related weight variation, we measured b ody weight in a convenience sample of 195 adults. The subjects were weighed four times at intervals of six to eight weeks, so that weight change was d etermined for three periods: preholiday (from late September or early Octob er to mid-November), holiday (from mid-November to early or mid-January), a nd postholiday (from early or mid-January to late February or early March). A final measurement of body weight was obtained in 165 subjects the follow ing September or October. Data on other vital signs and self-reported healt h measures were obtained from the patients in order to mask the main outcom e of interest. Results: The mean (+/-SD) weight increased significantly during the holiday period (gain, 0.37+/-1.52 kg; P<0.001), but not during the preholiday peri od (gain, 0.18+/-1.49 kg; P=0.09) or the postholiday period (loss, 0.07+/-1 .14 kg; P=0.36). As compared with their weight in late September or early O ctober, the study subjects had an average net weight gain of 0.48+/-2.22 kg in late February or March (P=0.003). Between February or March and the nex t September or early October, there was no significant additional change in weight (gain, 0.21 kg+/-2.3 kg; P=0.13) for the 165 participants who retur ned for follow-up. Conclusions: The average holiday weight gain is less than commonly asserted . Since this gain is not reversed during the spring or summer months, the n et 0.48-kg weight gain in the fall and winter probably contributes to the i ncrease in body weight that frequently occurs during adulthood. (N Engl J M ed 2000;342:861-7.) (C)2000, Massachusetts Medical Society.