A prospective study of holiday weight gain

Abstract

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 body 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 determined for three periods: preholiday (from late September or early October to mid-November), holiday (from mid-November to early or mid-January), and postholiday (from early or mid-January to late February or early March). A final measurement of body weight was obtained in 165 subjects the following September or October. Data on other vital signs and self-reported health measures were obtained from the patients in order to mask the main outcome 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 period (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 October, 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 next 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 returned 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 net 0.48-kg weight gain in the fall and winter probably contributes to the increase in body weight that frequently occurs during adulthood.

Figure 1

Weight change in 195 subjects. Pre-holiday: interval from late September or early October, through mid-November (before Thanksgiving); Holiday: winter holiday interval from mid-November through early January (after New Year's Day); Post-holiday: interval from early January through late February or early March; Total: interval from first measurement in late September or early October through last measurement in late February or early March. *P<0.001, weight increase during the Holiday interval and P<0.002, Holiday vs. Post-Holiday interval. ^§P<0.003 weight increase over total measurement period from September through March.

Figure 2

Distribution of weight change. Over 50 percent of subjects had body weights that differed by no more than 1 kg at each of the 3 measurements.

Figure 3

Percent of subjects with major holiday weight gain, defined as ≥ 2.27 kg in 101 non-overweight (body mass index < 25 kg/m²), 54 overweight (body mass index ≥ 25 but < 30 kg/m²), and 40 obese (body mass index ≥ 30 kg/m²) subjects. 95 percent upper confidence interval is shown. There was a trend for a greater percentage of subjects to have a major holiday weight gain with increasing degree of overweight (P=0.06).

Figure 4

Self-reported changes in activity (A, P < 0.01) and in hunger (B, P < 0.001) were significantly related to weight change during the Holiday interval. Group sizes are given in parentheses for each category heading.