Background

The holiday season (November to January) alone, contributes to over half of the annual weight gain in adults. Self-reported data indicates the reason for weight gain to be either increased energy intake or decreased physical activity, though objective techniques have never been used to assess this. We aimed to establish relative contributions of energy expenditure and intake on weight gain during holidays.

Methods

Doubly labeled water for total energy expenditure measurement and total body water for body composition measurement were used during the pre-holiday (September to the mid-November) and holiday period (mid-November to early January). Subjective and objective (appetite-regulating hormones) measures of appetite, and behavioral measures of eating were also evaluated.

Results

In 23 overweight adults, body weight change during holidays (0.41 ± 0.42 kg) was significantly higher (p=0.02) than the body weight change during pre-holiday period (-0.86 kg ± 0.42 kg). The total energy expenditure (-3 ± 54 kcal/d) and total body fat (24 ± 33 %, p=0.95) did not differ during the pre-holiday and holiday period. Using the energy balance equation, we observed a trend for increase in calculated energy intake (+78 ± 1 kcal/day) in pre-holiday vs holiday period. During the holiday period, participants also reported higher hunger (3.93 ± 0.46 cm vs 4.9 ± 0.34 cm, p=0.04) and lower satisfaction level (4.52 ± 0.53 vs 3.5 ± 0.28, p=0.02), immediately after a meal preload. No differences in appetite hormone levels between the two periods were observed. We also found a significant increase in number of episodes of eating at sit-down restaurants which correlated with the increase in energy intake (r=0.475, p=0.03).

Conclusions

An increase in energy intake and subjective appetite levels contribute to weight gain during holidays. Change in eating behaviors may enhance the weight gain. These findings are critical in informingdevelopment of targeted interventions focused on excessive energy intake during holidays.