Background

While loss of control (LOC) eating is estimated to occur in up to 50% of patients following metabolic and bariatric surgery (MBS), mechanisms driving this concerning behavior are not fully understood. Some literature suggests that high levels of momentary negative affect (NA) prompt LOC eating post-MBS; however, it is unclear whether the strength of the relationship persists or changes with time elapsed since surgery. The current study utilized ecological momentary assessment (EMA) data to examine the prospective relationship between NA and LOC eating during the first three years post-MBS. Participants (N=150, 84.7% female, 77% White) responded to mood and LOC eating questions on their smartphone six times per day for seven days at 1-, 2-, and 3-years post-MBS. NA and LOC eating were rated on a 1-5 Likert scale, with higher scores indicating more severe symptoms. NA was used as a prospective predictor of LOC eating, and the analysis evaluated if number of years post-MBS strengthened or weakened (i.e. moderated) this relationship. A generalized linear mixed model demonstrated that NA predicted LOC eating for both within- and between-subjects (p's < .015). Years post-MBS moderated the prospective within-NA to LOC eating effectthe relationship remained unchanged from Year 1 to Year 2 (ꞵ=0.046, p=.689) but strengthened between Year 2 to Year 3 (ꞵ=0.297, p=.024). This suggests that NA becomes a more potent predictor of LOC eating as time passes post-MBS, which has important implications for interventions aimed at reducing LOC eating and promoting optimal weight outcomes in the post-surgical period.