Lifestyle determinants of the drive to eat: a meta-analysis

Abstract

Background: Obesity is emerging as the most significant health concern of the 21st century. Although this is attributable in part to changes in our environment-including the increased prevalence of energy-dense food-it also appears that several lifestyle factors may increase our vulnerability to this calorie-rich landscape. Epidemiologic studies have begun to show links between adiposity and behaviors such as television watching, alcohol intake, and sleep deprivation. However, these studies leave unclear the direction of this association. In addition, studies that investigated the acute impact of these factors on food intake have reported a wide variety of effect sizes, from highly positive to slightly negative.

Objective: The purpose of this article was to provide a meta-analysis of the relation between lifestyle choices and increases in acute food intake.

Design: An initial search was performed on PubMed to collect articles relating television watching, sleep deprivation, and alcohol consumption to food intake. Only articles published before February 2012 were considered. Studies that took place in a controlled, laboratory setting with healthy individuals were included. Studies were analyzed by using 3 meta-analyses with random-effects models. In addition, a 1-factor ANOVA was run to discover any main effect of lifestyle.

Results: The 3 most prominent lifestyle factors-television watching, alcohol intake, and sleep deprivation-had significant short-term effects on food intake, with alcohol being more significant (Cohen's d = 1.03) than sleep deprivation (Cohen's d = 0.49) and television watching (Cohen's d = 0.2).

Conclusions: Our results suggest that television watching, alcohol intake, and sleep deprivation are not merely correlated with obesity but likely contribute to it by encouraging excessive eating. Because these behaviors are all known to affect cognitive functions involved in reward saliency and inhibitory control, it may be that they represent common mechanisms through which this eating is facilitated.

FIGURE 1.

Flow chart of the literature search and study selection process.

FIGURE 2.

Forest plots (meta-analyses, random-effects models) indicating the cumulative effect sizes (Cohen's d) for the impact of alcohol intake, sleep deprivation, and television watching on acute food intake. Sleep-deprivation studies observed intake over the entire day, whereas alcohol and television studies observed single meals. TV, television.

FIGURE 3.

Graph indicating the relative cumulative mean (±SEM) effect size on food intake for alcohol consumption, sleep deprivation, and television watching. A 1-factor ANOVA showed a significant main effect, such that alcohol's effect size was greater than television's effect size (P < 0.001) and trended toward being larger than that of sleep deprivation (P < 0.10). There was no difference between television watching and sleep deprivation. The effect size was greatest for alcohol (Cohen's d = 1.03, n = 278, P < 0.001), followed by sleep deprivation (Cohen's d = 0.49, n = 78, P < 0.05) and television watching (Cohen's d = 0.2, n = 363, P < 0.05). **P < 0.001, ^#P < 0.10. ns, nonsignificant; TV, television.

FIGURE 4.

Diagram representing mechanisms that might explain the connection between the lifestyle factors of alcohol consumption, sleep deprivation, and television watching and food intake. By increasing the saliency of food reward and decreasing inhibitory control, these lifestyle factors encourage the acute drive to food consumption, particularly for rewarding food. Chronic exposure to these lifestyle factors also leads to conditioned memories, which in turn enhance reward response to food and the subsequent drive to eat. Thus, these lifestyle factors, experienced chronically, could lead to susceptibility to food addiction and obesity. TV, television.