Loss of control eating exhibits an evening diurnal shift among females with bulimia nervosa and binge-eating disorder.

Loss of control (LOC) is a hallmark feature of binge eating that is associated with significant distress and impairment. Despite the central role diurnal rhythms may play in the development and maintenance of LOC eating, diurnal patterns of LOC remain understudied and poorly characterised. We assessed the diurnal timing of LOC in a sample of females with bulimia nervosa and binge-eating disorder who participated in a study assessing the impact of bright light exposure on binge eating, hypothesising that higher ratings of LOC would be more likely to occur later in the day. Participants (N = 34) completed a 22-day protocol during which they provided LOC ratings six times daily. Kernel density estimates describing LOC ratings across times of day were compared using permutation tests of equality. Results demonstrated an evening shift in LOC, wherein higher LOC was more likely to occur later in the day and lower LOC was more likely to occur earlier in the day. This study is the first to clearly depict the phenomenon that the likelihood of experiencing higher LOC increases throughout the day, pointing to the potential role diurnal rhythms, such as disrupted appetitive rhythms or mood variations, may play in maintaining binge eating.