Contextual factors influence food intake at eating occasions in young adults: A mixed effect analysis

Understanding eating behaviours of young adults is crucial for developing strategies to improve their diet quality. Factors that influence eating behaviours are often multifaceted and highly contextual, with little research focused on young adults. This study examined contextual factors influencing food intake at eating occasions among young adults. Participants (n = 675, 18-30 years) recorded dietary intake and contextual characteristics at eating occasions (n = 27,513) using a smartphone food diary ("FoodNow") over three to four non-consecutive days. Food and beverage intakes were classified into six groups according to the Australian Dietary Guidelines. Eating occasion-level contextual factors, such as consumption location, purchase location, activity, and social context, were recorded via the app, while person-level contextual factors were collected through an online survey. Generalised mixed models with random intercepts were used to investigate effects of contextual factors on food group consumption at meals and snacks. Eating location was associated with vegetable and discretionary food intake; meals that were eaten while in transit were 0.59 serves lower in vegetables (95% CI: -0.93, -0.38; p < 0.001) and 0.31 serves higher in discretionary foods (95% CI: 0.03, 0.54; p = 0.014), compared meals eaten at home. Higher intakes of discretionary foods were observed when friends were present at meals and snacks (0.66 and 0.57 serves, 95% CI: 0.56, 0.88; 0.36, 0.77, p < 0.001). Meals purchased from convenience stores were higher in grain and discretionary foods than meals from other locations (p < 0.001). Majority of person-level factors showed minimal effects on food group consumption. Addressing factors such as purchase location and social contexts during meals and snacks may improve food choices, as small changes at eating occasions can significantly impact overall diet quality over time.