Discordance between percentage of excess weight loss and body composition outcomes after bariatric surgery: a retrospective observational study.

BACKGROUND

Percentage of excess weight loss (%EWL) is one of the most commonly used criteria for assessing outcomes after bariatric surgery (BS). However, this measure is based on weight and does not provide information on body composition.

OBJECTIVES

Our aim was to evaluate the achievement of different anthropometric objectives 12 mo after BS, to analyze the concordance between %EWL and fat mass percentage (FM%) and waist-to-height ratio (WHtR), and to explore the differences in body composition and biochemical variables between and within groups of %EWL.

METHODS

A total of 583 participants (160 males/423 females) who underwent BS (109 sleeve gastrectomy/474 Roux-en-Y gastric bypass) were included in a retrospective observational study. %EWL, FM% and other anthropometric and biochemical variables at 12 mo postsurgery were analyzed using chi-square test and 1- or 2-way analysis of variance.

RESULTS

A total of 95% of the cohort achieved a %EWL ≥50% whereas 63% achieved a %EWL ≥75%. However, one-third of patients with %EWL ≥75% had an FM% still corresponding to obesity, and 65% had a WHtR ≥0.50. Patients with "high %EWL and high FM%" had higher body mass index, FM%, WHtR, trunk fat percentage, visceral adiposity, and relative fat mass than those with "high %EWL and low FM%" group (P < 0.001). Patients with "high %EWL and low WHtR" had lower levels of uric acid, blood pressure, and triglyceride-glucose index, as well as higher levels of quantitative insulin sensitivity check index than patients with "high %EWL and high WHtR" (P < 0.05).

CONCLUSIONS

Body composition variability within groups remains high, with a significant number of patients who, despite reaching the %EWL threshold, still exhibit a high FM% and WHtR. Complementing the %EWL with body composition measures allows for better characterization of patients as well as identification of those with a more unfavorable metabolic state, not only at diagnosis but also at follow-up.