The Influence of Meal Timing on Body Mass Index (BMI), Eating Behaviour Traits, and Health Behaviours

Emerging evidence indicates late eating can be related to a higher BMI. However, findings are inconsistent and the psychological and behavioural characteristics of early versus late eaters are unclear. Thus, the current thesis aimed to i) explore the associations between meal timing, BMI, eating behaviour traits (uncontrolled eating, craving control, emotional eating, cognitive restraint and satiety responsiveness) and health behaviours such as physical activity and sleep, ii) compare the differences in eating behaviour traits and health behaviours between early versus late eaters, and explore the factors that may contribute to late eating and understand the enablers and barriers of changing late evening eating.

A narrative review (Chapter 2) was conducted to provide an overview of the current literature within meal timing, body weight, eating behaviour traits and health behaviours. Chapter 3 introduced the methods, procedures and measurements used in the studies. An online survey (Chapter 4) (n = 260) showed that later eating was not significantly associated with BMI, yet late eaters reported significantly lower craving control and longer daily consumption window than early eaters. Other eating behaviour traits and health behaviour were not significantly different between early versus late eaters. A 14-day pilot study (Chapter 5) using objective measures of height, weight, physical activity and sleep in adults living with obesity (n = 30), demonstrated that later eating was significantly associated with higher uncontrolled eating, but not with higher BMI. Compared with early eaters, late eaters consumed significantly less %protein and reported poorer dietary quality. Chapter 6, using qualitative methods, identified four main contributors to late evening eating: internal signals; external and situational factors; social factors, and behavioural and emotional factors. Time constraints and work schedules were identified as main barriers to changing late evening eating. Recommendations are provided on interventions that may be effective for individuals at risk of overweight and obesity.

Using quantitative and qualitative methods, this thesis identified the eating behaviour traits linked with overconsumption and health behaviours related to late eating. Practical strategies to address barriers to changing late evening eating are also provided.