Metabolic and Bariatric Surgery as a Therapeutic Option for MASLD: Outcome, Mechanism, and Long-Term Implications

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease and a major hepatic manifestation of metabolic syndrome. It is closely linked to obesity and type 2 diabetes mellitus. While many patients display a steatotic liver, some progress to steatohepatitis, fibrosis, and cirrhosis, increasing the risk of hepatocellular carcinoma (HCC). Current management targets metabolic risk factors. Metabolic and bariatric surgery (MBS) has therefore emerged as both an obesity treatment and a therapeutic option for MASLD. This narrative review summarizes evidence on clinical outcomes, efficacy, and mechanisms. Histology-based studies show MASLD resolution and relevant fibrosis regression after MBS, with durable benefits. Comparative studies indicate superiority over lifestyle intervention and conservative treatment, while direct comparisons with modern drugs (e.g. GLP-1 agonists) remain limited. Mechanistic studies suggest that MASLD remission by MBS is driven through a combination of sustained weight loss and surgery-specific effects on hepatic lipid metabolism, mitochondrial function, glucose metabolism, incretin and bile acid signalling, adipose tissue biology, and the gut-liver axis. Emerging evidence suggests fewer liver-related events and lower HCC incidence, with potential benefits in selected high-risk patients. In conclusion, MBS is not merely a weight loss intervention, but a disease-modifying, multi-system metabolic therapy with direct hepatic effects.