Background: Despite their good intentions, people often do not eat healthily. This is known as the intention-behavior gap. Although the intention-behavior relationship is theorized as a within-person process, most evidence is based on between-person differences.
Purpose: The purpose of the present study is to investigate the within-person intention-behavior association for unhealthy snack consumption.
Methods: Young adults (N = 45) participated in an intensive longitudinal study. They reported intentions and snack consumption five times daily for 7 days (n = 1068 observations analyzed).
Results: A within-person unit difference in intentions was associated with a halving of the number of unhealthy snacks consumed in the following 3 h (CI95 27-70 %). Between-person differences in average intentions did not predict unhealthy snack consumption.
Conclusions: Consistent with theory, the intention-behavior relation for healthy eating is best understood as a within-person process. Interventions to reduce unhealthy snacking should target times of day when intentions are weakest.
Keywords: Ecological momentary assessment; Health behavior; Intention-behavior gap; Intraindividual and interindividual associations; Snack consumption.