White BA, Horwath CC, Conner TS (2013) Br J Health Psychol. 2013 Jan 24. doi: 10.1111/bjhp.12021
Prior research has focused on the association between negative affect and eating behaviour, often utilizing laboratory or cross-sectional study designs. These studies have inherent limitations, and the association between positive affect and eating behaviour remains relatively unexplored. Therefore, the objective of this study was to investigate the bidirectional relationships between daily negative and positive affective experiences and food consumption in a naturalistic setting among healthy young adults.
Daily diary study across 21 days (microlongitudinal, correlational design).
A total of 281 young adults with a mean age of 19.9 (±1.2) years completed an Internet-based daily diary for 21 consecutive days. Each day they reported their negative and positive affect, and their consumption of five specific foods. Hierarchical linear modelling was used to test same-day associations between daily affect and food consumption, and next-day (lagged) associations to determine directionality. Moderating effects of BMI and gender were also examined in exploratory analyses.
Analyses of same-day within-person associations revealed that on days when young adults experienced greater positive affect, they reported eating more servings of fruit (p = .002) and vegetables (p < .001). Results of lagged analysis showed that fruits and vegetables predicted improvements in positive affect the next day, suggesting that healthy foods were driving affective experiences and not vice versa. Meaningful changes in positive affect were observed with the daily consumption of approximately 7-8 servings of fruit or vegetables.
Eating fruit and vegetables may promote emotional well-being among healthy young adults.
What is already known on this subject? Laboratory and cross-sectional studies have found a strong link between experiences of negative affect and food consumption. These studies generally show that people eat more food and less healthy food when experiencing negative affect; however, there is less evidence of this association in a natural setting. Moreover, the association between positive affect and eating remains relatively unexplored. Some studies have found stronger links between negative affect and unhealthy food consumption among women and individuals with higher BMI. Conversely, the foods people eat may influence their affective experiences. Cross-sectional research has shown that a diet high in fruits and vegetables is associated with a lower lifetime prevalence of depression and anxiety, but it is not known whether healthy food consumption may also influence affective experiences on a day-to-day basis. What does this study add? Using online daily diaries for three weeks, we found strong relationships between daily positive affect and fruit and vegetable consumption. Lagged analyses showed that fruit and vegetable consumption predicted improvements in positive affect the next day, and not vice versa. Gender and BMI were not major factors in these associations. Fruit and vegetable consumption may promote feelings of well-being among healthy young adults.