A total weight loss of 25% shows better predictivity in evaluating the efficiency of bariatric surgery.

Objectives: The need for a unified definition of weight loss (WL) after bariatric surgery has recently been highlighted. We aimed to evaluate the reliability of two clinically common WL indications including percentage of total WL (%TWL) and percentage of excess WL (%EWL) through comparing their performances in predicting metabolic syndrome (MetS) remission 1 year after bariatric surgery.

Methods: A total of 430 individuals with obesity who underwent bariatric surgery were enrolled. Participants were evaluated for changes in anthropometric parameters, metabolic indexes, MetS components and medications before and 1 year after surgery. MetS was defined using the criteria of the National Cholesterol Education Program Adult Treatment Panel III criteria for Asian-Americans.

Results: The prevalence of MetS is 92.3% (397) at baseline. One year after bariatric surgery, 337 individuals (84.9%) were in MetS remission. The multivariate adjusted ORs were 1.16 (95% confidence interval [CI] 1.10-1.22) for each 1% increase in %TWL for MetS remission and 1.18 (95% CI 1.11-1.25) for each 5% increase in %EWL. This association with MetS remission remained statistically significant for %TWL after additional adjustment for %EWL (P for trend 0.029), and disappeared for %EWL. Receiver operating curve (ROC) analyses showed that the %TWL was more predictive than the %EWL (AUC vs. AUC, 0.749 vs. 0.700, p = 0.023). The Youden index indicated that the optimal %TWL cutoff point to identify MetS remission was 25%.

Conclusions: We recommend that good responders to bariatric surgery should be defined as those exhibiting %TWL ≥ 25%.