# Effectiveness of bariatric surgery on body mass, biochemical parameters, and steatosis in metabolically healthy vs. unhealthy obesity

## TL;DR

Bariatric surgery helps both metabolically healthy and unhealthy obese people lose weight and improve some health markers, but metabolically unhealthy individuals still show more liver issues and inflammation after surgery.

## Contribution

This study compares the effects of bariatric surgery on metabolically healthy versus unhealthy obese individuals, revealing differential outcomes in hepatic steatosis and inflammation.

## Key findings

- Bariatric surgery led to similar weight loss and improvement in metabolic parameters in both MHO and MUO individuals.
- MUO individuals showed higher residual hepatic steatosis and elevated markers of liver injury and inflammation after surgery.
- Hepatic steatosis was reduced in both groups, but more so in MHO individuals.

## Abstract

The effects of bariatric surgery in metabolically healthy obese (MHO) versus metabolically unhealthy obese (MUO) patients are underexplored in the literature.

The aim of the study was to compare the impact of bariatric surgery on weight loss, body composition, plasma biochemical parameters, and hepatic steatosis in MHO and MUO individuals.

Preoperative and 1-year postoperative medical records of 82 men and women aged 18–65 years, with body mass index >30 kg/m2, who underwent bariatric surgery from September 2021 to March 2023 were analyzed. MUO individuals were defined as those, metabolically unhealthy obese, with two metabolic syndrome risk factors, in preoperative data.

The prevalence of MHO and MUO individuals was 22 and 78%, respectively. Preoperative neck circumference and visceral adiposity index were higher in MUO individuals. Hepatic steatosis was the most common comorbidity in both groups. After 1 year, both groups demonstrated similar benefits from bariatric surgery in reducing body weight, adiposity, and anthropometric indices. Bariatric surgery also improved blood glucose, insulin sensitivity, and dyslipidemia in MUO individuals. However, 30% of MUO individuals presented with steatosis, compared to only 5.6% of MHO individuals. This outcome was accompanied by higher plasma levels of ferritin, alanine aminotransferase, and aspartate aminotransferase in MUO individuals.

Bariatric surgery provided similar benefits in body mass for MHO and MUO individuals. However, after 1 year, MUO individuals still exhibited elevated markers of inflammation, liver injury, and steatosis, suggesting greater residual metabolic vulnerability.

Bariatric surgery improved biometric parameters similarly in both MUO and MHO individuals.

Hepatic steatosis was reduced in both MUO and MHO groups following bariatric surgery.

Approximately 30% of MUO subjects continued to exhibit steatosis and elevated markers of hepatic inflammation and injury after surgery.

Obesity is a multifaceted and pervasive public health challenge related to comorbidities such as type 2 diabetes mellitus, cardiovascular disease, sleep apnea, kidney disease, some types of cancer, and non-alcoholic fatty liver disease. It is reported that around 15%–36% of people with obesity display preserved metabolic health and do not exhibit such obesity comorbidities. These subjects are called metabolically healthy obese, in which the body fat excess is not accompanied by insulin resistance, dyslipidemia, or hypertension. On the other hand, most obese individuals present impairments in metabolic health and the comorbidities of obesity; thus, these are referred to as metabolically unhealthy obese.

Bariatric surgery led to a similar effectiveness in weight loss, reductions in adiposity and anthropometric indices, and improvement in plasma glucose, lipids, insulin sensitivity, and renal parameters among metabolically unhealthy obese (MUO) and metabolically healthy obese (MHO) individuals. However, the effects of bariatric surgery between the MUO and MHO phenotypes differed significantly on hepatic steatosis and biochemical parameters of inflammation and liver damage, indicating that 1 year of the surgical intervention has better outcomes on hepatic steatosis in MHO individuals.