Differential effects of eating and drinking on wellbeing-An ecological ambulatory assessment study.

INTRODUCTION: Various behaviors, such as physical activity and sleep, have been shown to have stress-reducing and beneficial effects on wellbeing. In contrast, the rewarding effects of eating and drinking have rarely been investigated, particularly using ecologically valid approaches, and little is known about mediating mechanisms on the biological level.
METHODS: Seventy-seven healthy young adults completed items on eating and drinking as well as momentary wellbeing (measured by mood, energy, tension, stress and fatigue levels) on an iPod touch 5×/day for 4 consecutive days. With each entry, a saliva sample was collected for the later assessment of cortisol, alpha-amylase and salivary flow rate as markers of neuroendocrine and autonomic activity, respectively.
RESULTS: Hierarchical linear models showed better momentary wellbeing on various scales after the consumption of juice, coffee and alcohol. Having a snack predicted lower fatigue levels. In contrast, consuming high-fat food resulted in impaired wellbeing. With regard to affect-induced eating as well as biomarkers, only a few associations emerged as significant. However, autonomic activity partially mediated the alcohol-stress association.
CONCLUSION: These findings corroborate previous reports that dietary behaviors could have rewarding effects, but also challenge the assumption of a general mood-enhancing and stress-relieving effect of certain foods. Findings on biomarkers provide first insights into underlying biological mechanisms. Research on further assumed mechanisms (reward-associated brain networks) and moderators (hedonic overeating) is highly warranted. Moreover, implications for addiction research are discussed.