What, when and why we eat: Associations with obesity in adults

Background Understanding obesity development and formulating strategies for weight management relies on knowledge of behaviours and traits that influence dietary intake. Aims 1) To examine the association between individual-level behaviours and traits with dietary intake, with a focus on discretionary energy intake 2) to determine if these behaviours and traits were associated with obesity. Methods A systematic review and meta-analysis were conducted to determine the association of the proportion of energy consumed at night and BMI and weight loss. A cohort study was conducted to examine the association of bedtime and several psychological factors with dietary intake and obesity. The relationship between discretionary intake, core intake and obesity were modelled. The frequency and experience of food craving in people who had and had not received bariatric surgery were investigated. Results and discussion The proportion of energy eaten at night was weakly and positively associated with BMI but not weight loss. Bedtime was not associated with total energy intake or obesity but was associated with eating more discretionary energy at night. Discretionary and total energy intake were consistently and positively associated with daily rated negative affect and appetite, respectively. Interactions with obesity status were non-significant. Core and discretionary energy intake correlated negatively, potentially connoting dietary compensation. This correlation was weaker in participants with obesity. Participants with obesity reported more frequent and stronger food cravings than those of healthy weight and post-bariatric surgery. Conclusions Negative mood, food craving and night time eating behaviour can influence dietary intake. These factors are not associated independently with obesity but may contribute to weight gain. As they operate differently on discretionary and core intake, dietary quality and compensation should be emphasised in lifestyle weight management interventions