Replication and extension of dietary adherence as a predictor of suboptimal weight-loss outcomes in postbariatric patients

Abstract Background Sarwer and colleagues ( 1 ) found poor dietary adherence at 6-months postoperative predicted lower weight loss. Objectives To replicate and extend these findings. Setting University bariatric clinic Methods Fifty-four adults [72% female, 51.1±11.3 years, mean body mass index (BMI)=43.8±7.4 kg/m 2 , 53.7% = Roux-en-Y gastric bypass, 42.6%=laparoscopic sleeve gastrectomy, and 3.7%=gastric banding] were identified as low or high dietary adherers following Sarwer and colleagues’ methods. Patients self-reported dietary adherence with a 9-point Likert scale. Splitting at the median, low adherers scored d effect sizes were used to compare between-group outcomes. Results BMI did not differ between low (n=24) and high (n=30) dietary adherers at 6-months after surgery. At 12-months, the BMIs of low (n=17) versus high (n=25) adherers were significantly higher (34.1±4.61 vs. 30.3±3.90 kg/m2, p =.006, d =0.90), with significantly less %EWL (49.0%±24 vs. 70.7%±21.5; p =.004; d =0.95) and %TWL (20.7%± 11.5 vs. 28.9±10.5, p=.02, d= 0.74 ) . At 24-months, BMIs remained significantly higher for low (n=12) versus high (n=10) adherers (33.7±4.77 vs. 29.7±3.82 kg/m 2 , p =.045, d =0.92), but %EWL and %TWL were not significant, despite large effect sizes. At 36-months, moderate effects supported continued higher BMIs and lower %EWL and %TWL for low (n=5) versus high (n=8) adherers. Attrition from follow-up: 22.2% (12-months), 59.3% (24-months), 75.9% (36-months). Post-hoc analyses revealed no impact of baseline characteristics on low follow-up rates except younger age (at 1 year). Conclusions Findings that 6-month post-operative dietary adherence predicts 12-month BMI, %EWL, and %TWL were replicated. Medium to large effects suggest findings extend to 24 and 36-months, with low follow-up rates likely impacting statistical significance.