The Effect of Bariatric Surgery on Serum Lipid Profile Levels in Patients With Morbid Obesity: A Systematic Review



Nazar E ; Farmani E ; Baloochi K ; Nozheh A
Source: Tehran University Medical Journal Published:2026

Abstract

Background: Morbid obesity is a chronic, multifactorial disease associated with a range of metabolic disturbances, most notably dyslipidemia, which significantly elevates the risk of cardiovascular morbidity and mortality. Bariatric surgery has emerged as the most effective long-term treatment for severe obesity, yielding substantial and sustained reductions in both subcutaneous and visceral adipose tissue. Despite this well-documented effect on fat mass, a lack of consensus persists regarding the magnitude and durability of the associated changes in serum lipid profiles. While numerous individual studies have reported beneficial effects, the overall evidence has not been systematically quantified to provide a clear, overarching conclusion. This study was therefore designed to conduct a comprehensive systematic review and meta-analysis, synthesizing data from the existing literature to precisely evaluate the impact of various bariatric surgical procedures on key lipid parameters in patients with morbid obesity. Methods: A systematic literature search was meticulously performed using predetermined keywords across major electronic databases, including PubMed/MEDLINE, Web of Science, EMBASE, Scopus, ProQuest, CENTRAL, and PEDro, to identify all relevant studies published up to the search date. Two independent reviewers conducted the study selection, data extraction, and quality assessment, resolving any discrepancies through consensus or consultation with a third reviewer. The primary outcomes were mean changes from baseline in serum total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride levels. A random-effects model was applied for the meta-analysis to account for heterogeneity between studies, and all statistical analyses were performed using Comprehensive Meta-Analysis (CMA) software. Results: The final analysis included 27 eligible studies that met the predefined inclusion criteria. The pooled results demonstrated that bariatric surgery, irrespective of the specific technique (including gastric bypass, sleeve gastrectomy, and gastric banding), was associated with statistically significant and clinically meaningful improvements in all lipid profile parameters. At 12 to 24 months post-surgery, significant reductions were observed in serum total cholesterol, LDL cholesterol, and triglyceride levels, alongside a significant increase in serum HDL cholesterol. Critically, this favorable effect on the lipid profile was not transient; the improvements were sustained over the long term, with evidence demonstrating persistent and significant beneficial changes in all measured lipid parameters even beyond the five-year postoperative mark. Conclusion: This meta-analysis provides robust evidence that bariatric surgery induces profound and durable improvements in the serum lipid profile of patients with morbid obesity. The effectiveness of these interventions in reducing atherogenic lipids (total cholesterol, LDL, and triglycerides) while increasing protective HDL cholesterol is maintained for at least five years after the procedure, underscoring the sustained metabolic benefit and supporting bariatric surgery as a pivotal strategy for long-term cardiovascular risk reduction in this patient population. Copyright © 2026 Nazar et al. Published by Tehran University of Medical Sciences. This work is licensed under a Creative Commons Attribution-Non-Commercial 4.0 International license (https://creativecommons.org/licenses/by-nc/4.0/). Non-commercial uses of the work are permitted, provided the original work is properly cited.