BackgroundThe longitudinal association between specific eating behaviors, such as skipping breakfast and night eating, and changes in weight and waist circumference (WC) has been understudied. ObjectivesThe objective of this study was to investigate whether skipping breakfast and night eating were individually or jointly associated with the annual changes in weight and WC. MethodsIn the current longitudinal study, included were 48,150 Chinese adults (mean age: 50.1 ± 13.9 y) who were free of diabetes, cardiovascular diseases, and cancer in 2014, when data on dietary intake and the presence of night-eating behavior and skipping breakfast were collected via questionnaires. Weight and WC were measured repeatedly in 2014, 2016, and 2018. The associations between night eating and/or skipping breakfast and annual changes in weight and WC were evaluated using the generalized estimating equation models, adjusting for age, sex, total energy, diet quality, and other potential confounders. ResultsDuring 4-y of follow-up, among people who had both 2 unhealthy eating behaviors, the mean difference in annual weight change was 0.53 kg (95% confidence interval: 0.43, 0.63 kg) and 0.41 cm (95% confidence interval: 0.27, 0.55 cm) in annual WC change, compared with participants without either behavior. The associations of eating behaviors and change in weight and WC were more pronounced in participants with higher baseline body mass index (in kg/m2) relative to their counterparts. Similarly, the associations between these eating behaviors and WC change were stronger in those with poorer diet quality relative to those with better diet quality. ConclusionsIndividuals with frequent skipping breakfast and/or night eating experienced faster gains in weight and WC, even after adjusting for diet quality and energy intake.