GLP-1s and Fatty Liver Disease (MASH): The Evidence

Metabolic dysfunction-associated steatohepatitis — MASH, formerly called NASH — is the inflammatory, scarring end of fatty liver disease. It tracks closely with obesity and type 2 diabetes, which is exactly why GLP-1 receptor agonists became an obvious thing to test: a drug class that drives weight loss and improves glucose handling sits squarely in the disease’s underlying biology. For years the trial picture was promising but unsettled. A large phase 3 trial has now changed that.

What the ESSENCE trial showed

ESSENCE is a phase 3, randomized, double-blind, placebo-controlled trial of once-weekly subcutaneous semaglutide 2.4 mg in adults with biopsy-confirmed MASH and moderate-to-advanced fibrosis (stage F2 or F3). Its 72-week histology results were published in The New England Journal of Medicine in April 2025, drawn from roughly 800 randomized participants. Medical, appointment, doctor — illustrating GLP-1s and Fatty Liver Disease (MASH): The Evidence

The trial met both of its primary endpoints:

Endpoint at week 72	Semaglutide 2.4 mg	Placebo
Resolution of steatohepatitis, no worsening of fibrosis	62.9%	34.3%
Improvement in fibrosis, no worsening of steatohepatitis	36.8%	22.4%

Both differences were statistically significant (P<0.001 for each). For years, the weak spot in earlier GLP-1 trials had been fibrosis — the scar tissue that actually predicts cirrhosis and liver failure, and which had been more stubborn than inflammation. ESSENCE is the first phase 3 GLP-1 trial to show a statistically significant fibrosis benefit on top of the more expected reduction in steatohepatitis.

ESSENCE showed semaglutide both resolved steatohepatitis (62.9% vs 34.3%) and improved fibrosis (36.8% vs 22.4%) versus placebo at 72 weeks — the inflammation and, importantly, the scarring both moved.

What this does and doesn’t settle

Visual, visual test, vision — illustrating GLP-1s and Fatty Liver Disease (MASH): The Evidence

Histology improved on the two endpoints that matter most for MASH staging.
Mechanism is likely indirect — much of the benefit plausibly flows through weight loss and improved insulin sensitivity rather than a direct hepatic action.
Hard outcomes are still pending. ESSENCE was designed to continue treatment for up to 240 weeks; the 72-week readout is histology, not yet long-term events like cirrhosis, liver failure, or death.
Fibrosis still resolved in only a minority — 36.8% is a real, significant improvement, but most treated patients did not achieve fibrosis improvement.

The takeaway

The honest framing for MASH has shifted. GLP-1 therapy is no longer just a credible frontier riding on metabolic plausibility — semaglutide now has positive phase 3 histology data on both steatohepatitis resolution and fibrosis improvement. What remains unproven is whether those histologic gains translate into fewer hard outcomes over the long run, which the ongoing ESSENCE outcomes phase is designed to test. For people with MASH and coexisting obesity or diabetes, the metabolic case was always strong; the liver-specific case is now considerably stronger, with the long-term outcome question still open.