Within-person associations of psychological factors with healthy or unhealthy diet in EMA studies in general adult populations: A systematic review and meta-analysis

Background . (Un)healthy eating behaviours may vary by moment and psychological context. Ecological momentary assessment (EMA) is well-suited to study within-person, momentary and context-dependent behaviours and correlates, as it uses repeated sampling of real-time experiences. Insights in such within-person relations could inform ecological momentary interventions. A systematic review and meta-analysis of these insights in a healthy population is, however, currently lacking. Objective. The aim of this systematic review and meta-analysis was to synthesise within-person associations between psychological factors and eating behaviour in healthy adults and summarise methodological aspects of these studies. Methods. Observational and experimental studies on psychological predictors of (un)healthy eating behaviours in adult healthy populations were included, based on a systematic search of Ovid MEDLINE, Embase, PsycINFO and Web of Science. Meta-analysis of ³5 studies per predictor/outcome was performed in metafor R-package. Results . Forty-nine (review) and fifteen studies (meta-analysis) were included. Most studies were observational and used fixed time-based sampling, and most assessed food eaten since the last prompt/timeframe. Various measures reported on study adherence (between 79-90%). Only around half reported on reliability and/or validity of the predictors or outcomes, most often referring to an adaptation of non-EMA scales, with little information of their exact adaptation. Due to high diversity in conceptualization and reporting of effect sizes, not all could be meta-analyzed. A first meta-analysis (β=-0.007, p=.006, k=8, n total=1,489) showed negative psychological triggers (NPT, e.g., negative affect, daily stress, and ruminations) predicted lower levels of healthy eating behaviour. A second showed NPT predicted higher levels of unhealthy eating behaviour (β=0.054, p=.022, k=6, n total=1,578), whereas the third did not show a significant association between NPT and unhealthy behaviour event occurrence when pooling the logOR (logOR=.469, p=.095, k=5, n total=944). Conclusions. Negative psychological triggers predict less healthy eating behaviours at a within-person level in a healthy adult population, but mixed evidence for unhealthy eating. This highlights their importance to be included in health promoting ecological momentary interventions. Methodological assessment of the studies shows a need for reliability and validity reporting guidelines for EMA measures.