Less is more: A smartphone EMA study manipulating frequency of assessment of unhealthy snacking

Background: Self-monitoring is an effective strategy for reducing unhealthy snacking, and smartphone Ecological Momentary Assessment (EMA) may promote behavioral change through measurement reactivity. However, it remains unclear whether higher monitoring frequency enhances these effects or, instead, increases burden. Method: Throughout a 3-week EMA protocol, 136 healthy-BMI female participants - mostly University students - were randomly assigned to either a low (3/day), medium (6/day), or high (9/day) monitoring condition. Every day, multiple times per day, participants reported cravings (degree and amount), intake, self-control, and stress. Generalized linear mixed-effects models tested changes over time and differences between conditions. It was hypothesized that higher monitoring frequency would produce stronger reductions in craving and snacking (H1), with effects moderated by self-control (trait), dietary restraint, and hedonic hunger (H2). Results: Across conditions, craving (degree and amount) and snacking decreased significantly over time, supporting a general measurement reactivity effect. Against H1, the high monitoring condition did not produce steeper reductions in craving or snacking compared to lower monitoring conditions. This effect was further supported by Bayesian analysis results. Finally, against H2, self-control (trait), dietary restraint, and hedonic hunger did not moderate the effect of monitoring frequency on craving and/or snacking. Conclusions: Smartphone EMA may be effectively used to reduce cravings and snacking through measurement reactivity. Importantly, the low monitoring conditions (3 beeps/day) emerged as the least burdensome, yet effective, approach to reduce craving and snacking over time in a non-clinical sample. Future research should test whether this EMA-induced measurement reactivity effect generalizes to clinical populations.