Snacking Behaviors in Relation to Stress and Physical Activity Using Automated Dietary Assessment: Observational Study

Background Snacks contribute 19% to 34% of daily energy intake, yet studying snacking behaviors faces challenges due to self-report biases. The SnackBox, an automated dietary assessment tool, enables structured measurement of snacking in seminaturalistic settings. Objective This study explored the relationships between snacking and perceived stress (case study 1) and physical activity (case study 2) using the SnackBox technology. Methods Forty-seven office workers (n=29, 61.7% female; mean age 28.8, SD 4.1 years) used the SnackBox at work and home for 2 weeks. The device recorded snack consumption (grams and time). Participants reported perceived stress via ecological momentary assessments and wore a Chill+ band and a Garmin wearable to track physical activity. Results Across the study period, 1455 ecological momentary assessments, 2933 hours of wearable data, and 2199 snacking events were recorded. Participants consumed a daily average of 769 (SD 772) kcal from snacks. Stress did not significantly impact snacking likelihood (χ21=0.2; P=.69). Snacking was more likely before vigorous physical activity (odds ratio 2.00; SE 0.39; P<.001). Conclusions The SnackBox demonstrated utility as a technology probe for exploring relationships between snacking and physiological and contextual factors. This approach enhances our understanding of snacking and supports personalized interventions and predictive models. Trial Registration ISRCTN Registry ISRCTN45046481; https://www.isrctn.com/ISRCTN45046481