Abstract
BACKGROUND/OBJECTIVES: The winter holiday season in the United States, which spans mid-November to mid-January, contributes to over half of annual body weight gain. Although self-reported data have linked this weight change to both increased energy intake and reduced physical activity, objective techniques have never been used; and thus, the actual cause of holiday weight gain is controversial. Here, we aimed to determine changes in components of energy balance leading to the holiday weight gain. METHODS: Body weight change was compared between the pre-holiday (mid-September to mid-November) and the holiday period (mid-November to early January). Total energy expenditure (TEE) was measured using doubly labeled water during holiday time (early to mid-December). Subjective (ratings) and physiological (appetite-regulating hormones) measures of appetite, eating-away-from-home frequency, and incentive salience of food pictures were also evaluated. RESULTS: In 23 obese adults (87% female), body weight change during the holidays (0.41 ± 0.42 kg) was significantly higher (P = 0.02) than the body weight change during the pre-holiday period (-0.86 ± 0.42 kg). TEE was unchanged during the two periods, suggesting no role of energy expenditure on weight gain. However, participants reported lower satisfaction after a meal pre-load which was significantly correlated with increased body weight during the holiday period. An increase in number of episodes of eating at sit-down restaurants was also reported during that period. Overall, these changing behaviors were supported by a non-significant increase in energy intake (+80 kcal/day, P = 0.07) observed during the study holiday period. CONCLUSION: We conclude that a decrease in energy expenditure does not result in the weight increase, but that increase in food intake is the more likely cause. Our data imply that compromised internal satiety mechanisms in presence of external food cues and diet-related behavioral variables during the holidays may influence weight gain.