Retatrutide for Fatty Liver: What the Study Really Found (and What You Can Do Now)

By The RX Index Editorial Team · Last verified October 2026

Retatrutide isn't FDA-approved for fatty liver, or anything else yet. In a study of 98 adults with excess weight and no type 2 diabetes, the 12 mg research group averaged 86% less liver fat at 48 weeks. Only nine of its 18 people had a usable scan then. That doesn't prove less scarring.

What changes this for you: how much scarring your liver has, whether you have type 2 diabetes (people with it weren't in the study), and whether you need care now. Two medicines are already FDA-approved for a serious kind of fatty liver, and one of them is a GLP-1.

Below is the detail that puts the headline in context: how many people each number actually rests on. Then where you fit, and what to do this month.

RX Index Decision Verdict: Big liver-fat results, but not an approved fatty liver treatment. If your liver needs care now, don't wait for it.

• Best for: following the science, or adults with high-risk fatty liver who might fit Lilly's enrolling liver study.
• Not ideal for: anyone with diagnosed MASH (fatty liver with inflammation and liver-cell damage), scarring, or cirrhosis who needs treatment now, and anyone thinking about "research" retatrutide sold online.
• The factor that matters most: your liver stage (how much scarring you have), not the size of the headline number.

Retatrutide fatty liver results: what each headline number really means

The retatrutide liver results below come from a Phase 2 study of 98 adults with excess weight and at least 10% fat in the liver, published in Nature Medicine in June 2024. Its main measure was liver fat on an MRI scan, not liver damage confirmed by a biopsy (a small tissue sample). Week 24 was the main liver endpoint; week 48 was follow-up. By week 48, fewer than half of the people had a usable scan. (Sanyal et al., Nature Medicine)

Here's every number you've probably seen, next to what it actually measured.

Checked October 24, 2026. Overall, 77 of 98 people had a usable week-24 scan and 43 of 98 had a week-48 scan. Missing scans came from stopping treatment early or a scan done outside the visit window; it doesn't mean everyone else dropped out. The main trial enrolled 338 people; 336 had data in its liver-safety analysis. The benefit results excluded data collected after people permanently stopped the study drug. Average changes used a model of repeated measurements; missing scans were statistically estimated for the under-5% results. Sources: Sanyal et al., Lilly, ClinicalTrials.gov.

What "86% less liver fat" means in real numbers

It's a percent of the fat you started with, not a percent of your liver. Here's the math with a made-up example.

Say your scan showed a liver-fat level of 20%. An 80% drop would take you to 4%, because 20 × 0.20 = 4. That's a fall of 16 percentage points, and it puts you under the 5% line the study used for "normal liver fat." This explains the math. It doesn't predict anyone's result.

The study's people started at about 19% liver fat on average.

The full results, dose by dose

Every dose of retatrutide lowered liver fat more than placebo did. The two highest doses, 8 mg and 12 mg, cut it by about 81% to 86%. Most of that drop happened in the first 24 weeks. (Sanyal et al.)

At week 48, 89% of the 8 mg group and 93% of the 12 mg group were estimated to be under 5% liver fat. The paper's text doesn't give those week-48 under-5% rates for 1 mg and 4 mg, so we don't guess. These doses are research groups, not dosing instructions. Changes in liver fat and weight are estimated group averages; under-5% figures are estimated shares of people. Neither predicts one person's result.

Retatrutide isn't a routine prescription option today. If you're considering a GLP-1 for weight, the right treatment path isn't the same for everyone. It depends on your state, your insurance and its drug list, FDA-approved or compounded, a shot or a pill, and your budget. Compounded drugs are not FDA-approved, and the FDA does not review their safety, effectiveness, or quality before they reach patients. (FDA)

Use The RX Index's Find My GLP-1 Path tool to see which fits before you choose. It's free, takes about 2 minutes, and needs no signup. It won't check your liver stage, confirm your coverage, or get you retatrutide.

See which GLP-1 path fits you

Why most of the drop came early

By week 24, people on 12 mg had lost about 18% of their body weight, and most of their liver fat was already gone. The study found liver fat hit near its low point at about 20% weight loss. After that, there just wasn't much fat left in the liver to lose. Belly fat kept shrinking.

Think of it like draining a sink. Once it's nearly empty, more draining doesn't change much.

Belly fat went down too

The deep belly fat around your organs, called visceral fat, fell 16% to 48% by week 48, depending on dose. On placebo, it rose 2.5%. Liver fat and belly fat moved together closely. For more, see our guide to GLP-1s for belly fat.

Can you get retatrutide for fatty liver now?

Not by routine prescription. Retatrutide isn't FDA-approved for fatty liver or any other condition. Access is limited to clinical trials and a narrow expanded-access program. Lilly plans to apply for FDA approval in early 2027, and it says its data supports filings for obesity, knee arthritis pain, and sleep apnea. Fatty liver isn't on that list. (Lilly, FDA, Lilly Medical)

So even if retatrutide is approved for weight loss, that wouldn't also be FDA approval to treat MASH. A liver indication would need its own proof.

Compounding isn't a back door either. The FDA says: "Retatrutide and cagrilintide cannot be used in compounding under federal law." It has also warned companies selling retatrutide labeled "for research purposes." (FDA) More on that in our page on compounded retatrutide.

Data-collection dates aren't results dates, and filing isn't approval. Sources: Lilly study page, ClinicalTrials.gov NCT07165028.

Lilly's enrolling liver study: SYNERGY-Outcomes

Lilly lists SYNERGY-Outcomes as enrolling. It's a Phase 3 study of about 4,500 adults with high-risk fatty liver. It tests whether retatrutide or tirzepatide (the medicine in Zepbound) can prevent serious liver problems, like cirrhosis, compared with placebo. (Lilly study page)

What to know before you call:

• You might get placebo. Treatment is assigned at random.
• It's long. About four and a half years, with around 30 visits.
• Fatty liver alone isn't enough. You need liver fat on MRI plus signs of scarring on tests that don't need a biopsy. The registry lists liver fat of 8% or more, an ELF blood-test score for scarring risk of 9 to 10.8, and a liver stiffness reading of 10 to under 20 kPa (the unit used for liver stiffness).
• Some people can't join: anyone with other liver disease, a BMI (body mass index) under 25, an A1C over 10% (a blood-sugar measure), type 1 diabetes, or more than 11 pounds lost in the 3 months before screening.
• Past cirrhosis needs a direct check. Lilly's summary rules out prior cirrhosis; the registry lists prior decompensated liver disease, such as fluid buildup or liver-related confusion. Ask the study team to confirm the rule for you.

If you want to explore it, start with the sponsor's own page: Lilly's SYNERGY-Outcomes study details. The Lilly Trial Information Center is 1-877-285-4559. For every retatrutide study in one place, see our retatrutide clinical trials tracker.

Expanded access requires more than a fatty liver diagnosis

Lilly has a narrow program where a treating doctor can request retatrutide for one patient. To be considered, you must be 18 or older with a BMI of 35 or higher despite taking and tolerating the highest available dose of a chronic weight-management medicine. You must also have at least two serious or life-threatening obesity-related health problems already receiving standard care, be unable to join a retatrutide or similar drug trial, and have talked through every standard option, including surgery. A fatty liver diagnosis alone doesn't qualify, and meeting the rules doesn't guarantee access. Medical suitability, location, and supply also matter. (Lilly Medical, last reviewed Aug 26, 2026)

The request has to come from your doctor, not you. Our retatrutide early access guide walks through it.

Does less liver fat mean less liver scarring?

Not necessarily. Liver fat and liver scarring are different things. This study measured fat on MRI and some blood markers, but it didn't use biopsies, so it can't show that retatrutide reverses scarring or treats MASH. Its own authors call the results "hypothesis-generating," meaning a starting point for bigger studies. (Sanyal et al.)

Here's the difference in plain words:

• MASLD (metabolic dysfunction-associated steatotic liver disease) is fat in the liver tied to things like extra weight, insulin resistance, or high blood sugar. Older papers call it NAFLD.
• MASH (metabolic dysfunction-associated steatohepatitis) is MASLD plus inflammation and liver-cell damage. It used to be called NASH.
• Fibrosis is scarring, rated from F0 (none) to F4 (cirrhosis).

Think of liver fat as grease in an engine, and scarring as the damage the grease caused over years. This study measured the grease. It didn't open up the engine.

A few other signals are worth knowing:

• Liver enzymes didn't move much. ALT and AST are liver enzymes in your blood. Their averages didn't change consistently versus placebo, but they were mostly normal to start.
• Scarring scores didn't move much either. FIB-4 and ELF, two scarring risk scores, also didn't change consistently.
• Two damage markers did drop. K-18, a marker of dying liver cells, fell up to 49.6%. Pro-C3, a marker of active scarring, fell up to 26.4%. Those are early hints, not proof.

Who the results don't cover

The study can't speak for everyone with fatty liver. Here's who it left out or barely included:

• Type 2 diabetes: excluded.
• Moderate or advanced scarring: only 7 of 98 people had higher-risk scarring scores. The authors say most likely had simple fatty liver or mild disease; biopsies weren't done to confirm their stages.
• Cirrhosis: not studied, so safety there is unknown.
• Diversity: all U.S. sites, 98% white participants.
• Independence: Lilly funded and designed the study, and the lead author has consulted for Lilly.

None of this means retatrutide doesn't help scarring. It means this study didn't show it.

Where do you fit? What to do for your liver now

If you have fatty liver, the most useful thing you can do this month isn't waiting for retatrutide. It's finding out how much scarring you have, because that decides your options. A FIB-4 score uses your age, AST, ALT, and platelet count, so it can usually be figured from routine blood work. (AASLD)

Under guidance from the American Association for the Study of Liver Diseases, a FIB-4 under 1.3 usually means low risk of advanced scarring for adults aged 35 to 64. A score of 1.3 or higher calls for a second test, like a liver stiffness scan (FibroScan, also called VCTE) or an ELF blood test. At 65 or older, the cutoff is 2.0. FIB-4 is less reliable under 35, so your doctor may use another test. FIB-4 estimates risk; it doesn't tell you your exact scarring stage.

Three quick questions to ask yourself:

1. Has a doctor told you your fibrosis stage, or given you a FIB-4 or FibroScan result?
2. Is your BMI 30 or higher, or 27 or higher with a weight-related condition like high blood pressure?
3. Do you have type 2 diabetes?

Then find your row.

This table points you to the right conversation. It isn't a diagnosis. Sources: AASLD, NIDDK on weight loss and liver fat, Wegovy label, Zepbound label, and NHS warning-symptom guidance. Checked October 24, 2026.

Say you're 48, a routine ultrasound showed fatty liver, and your BMI is 33. Retatrutide isn't a routine prescription option for you yet. A FIB-4 from your last labs helps your doctor decide whether you need a FibroScan. If your scarring risk is low, you can still ask about an approved GLP-1 for weight. Losing weight can lower liver fat.

Under 18, pregnant or planning a pregnancy, living with type 1 diabetes, or with a history of an eating disorder? Start with your own clinician before any program.

If your fatty liver is mostly tied to your weight, an approved GLP-1 for weight is a real option to discuss now. The right one still depends on your insurance, budget, and whether you'd rather take a shot or a pill.

Compare approved GLP-1 paths for your situation

Two FDA-approved options for MASH with scarring

If you're an adult with MASH, moderate to advanced scarring (stages F2 to F3), and no cirrhosis, two medicines have FDA approval for it. Both got accelerated approval, which means the FDA approved them based on liver biopsy improvements, and the makers still have to confirm clinical benefit in further studies. (Wegovy label, Rezdiffra label)

In Wegovy's main liver trial, called ESSENCE, 62.9% of people on Wegovy had their MASH resolve without scarring getting worse at 72 weeks, versus 34.3% on placebo. Scarring improved by at least one stage without MASH getting worse in 36.8% versus 22.4%. (Sanyal et al., New England Journal of Medicine)

Fat in the liver alone doesn't qualify you for either label. Your doctor has to confirm MASH and your scarring stage.

How retatrutide's liver data compares

These medicines were tested with different yardsticks, so their numbers can't be lined up like a race. Retatrutide's study measured liver fat on MRI. The others were tested with liver biopsies in people with MASH and scarring.

Sources: retatrutide liver study, ESSENCE, MAESTRO-NASH, SYNERGY-NASH, and the current Mounjaro and Zepbound labels. Prescribing an approved drug for a use outside its label is called off-label use; a clinician decides whether that fits.

For the full treatment decision by liver stage, see our guide to the best GLP-1 for fatty liver. For tirzepatide's biopsy results, see the SYNERGY-NASH study.

Five questions to take to your appointment

You don't need to know your stage before asking for help. Copy these and bring any reports and a list of your current medicines:

1. What is my actual diagnosis: fatty liver, MASH, scarring, or cirrhosis?
2. What do my tests show about scarring, and what's still unknown?
3. Which approved treatments fit my diagnosis and my other health conditions?
4. How will we check whether my liver is getting better?
5. If a study makes sense for me, what about placebo, visits, costs, and what happens when it ends?

Don't put off the appointment to fill in every blank. Our guide to GLP-1 lab monitoring explains common liver tests.

Is retatrutide hard on the liver?

In the Phase 2 trial, there was no liver-injury signal through 48 weeks, in either the 98-person liver group or the 336 people with liver-safety data in the parent trial. Stomach side effects were the most common problems, mostly mild to moderate. People with advanced scarring or cirrhosis weren't studied, so their safety is unknown. (Sanyal et al.)

A few more details from the liver study:

• Serious events: two people on retatrutide (2.5%) had serious problems, including one with gallbladder inflammation that needed surgery. Fast weight loss can raise gallstone risk; see GLP-1 gallbladder risk.
• Ketones: a fat-burning marker called beta-hydroxybutyrate rose, but no one developed ketoacidosis.

For the full picture, see retatrutide side effects.

"Research" retatrutide isn't the study drug

Products sold online as retatrutide, "Reta," or "R-10" are not Lilly's study medicine, and nobody can promise what's in them. In June 2026, health officials in Victoria, Australia reported six cases of acute liver injury in people who used unapproved products labeled retatrutide. They said a contaminant may be involved. (Victoria Department of Health) That alert doesn't show that real retatrutide hurts the liver. It shows that the vial and the study aren't the same thing.

If you've used one of these products and have tiredness, yellow skin or eyes, belly pain, dark urine, or unusual bruising, get medical care promptly. For a possible poisoning in the U.S., call Poison Control at 1-800-222-1222; you don't need to wait for symptoms. Call 911 for trouble breathing, a seizure, collapse, or someone who won't wake up. Our guide on how to avoid fake GLP-1 medications shows the warning signs.

Why might retatrutide lower liver fat so much?

Retatrutide acts on three hormone receptors (a receptor is like a lock on a cell that a hormone key fits into): GLP-1, GIP, and glucagon. In the study, liver fat fell in step with weight loss. Researchers think the glucagon part may also help the liver burn its own fat, but the study couldn't separate those two effects. (Sanyal et al.)

One clue: beta-hydroxybutyrate, a marker made when the liver burns fat, rose two to three times at the 4 mg dose and above. That's a hint, not proof that retatrutide works better than other drugs at the same weight loss. Our retatrutide vs tirzepatide page explains how the drugs differ.

What we actually verified

The RX Index is the independent GLP-1 decision resource that scores telehealth providers and treatment paths on clinical legitimacy, care quality, transparency, access, and cost, so readers can choose the path that fits their situation.

For this page, we read the full liver study and checked the current FDA status, drug labels, and Lilly's study and access pages on October 24, 2026. We didn't test any product, screen anyone for a study, or check anyone's insurance. Here's how we evaluate evidence and treatment paths.

What we couldn't confirm: week-48 "normal liver fat" rates for the 1 mg and 4 mg groups, which aren't in the paper's text. We also found no published liver results from any Phase 3 retatrutide trial.

Frequently asked questions

Does retatrutide remove fatty liver?

In one small study, most people on the two highest doses were estimated to reach normal liver fat (under 5%) on MRI. That's a fat measurement, not proof the liver is healed. The study didn't prove that retatrutide treats MASH or scarring, and it isn't an approved fatty liver treatment.

Can retatrutide treat liver fibrosis?

It hasn't been shown in this human study. The researchers didn't biopsy livers, and few people had blood-test signs of advanced scarring. One scarring-activity marker (Pro-C3) dropped, but scarring scores like FIB-4 and ELF didn't change consistently. The big liver outcomes study has an estimated end date of August 2032.

Does retatrutide help with visceral fat?

In the same trial, deep belly fat fell 16% to 48% by week 48, depending on dose, while it rose 2.5% on placebo. Belly fat and liver fat dropped together. See our guide to GLP-1s for belly fat.

Which GLP-1 is best for fatty liver?

Among GLP-1s, only Wegovy injection has FDA approval for a liver condition: MASH with F2–F3 scarring and no cirrhosis. If your fatty liver is mostly about weight and you have little scarring, the choice depends more on your coverage and goals. Our best GLP-1 for fatty liver guide breaks it down by stage.

Is retatrutide hard on the liver?

In the Phase 2 trial, there was no liver-injury signal through 48 weeks. It wasn't studied in people with cirrhosis. Products sold online as retatrutide are a separate risk, and some have been linked to liver injury.

Are liver enzymes the same as liver fat?

No. ALT and AST are liver enzymes in a blood test. An MRI measures how much fat is in the liver. In this study, liver fat fell a lot, but average ALT and AST didn't change consistently versus placebo.

Is retatrutide better than tirzepatide for fatty liver?

This study can't answer that, because it compared retatrutide with placebo. SYNERGY-Outcomes is testing both drugs, but each against placebo. Numbers from separate studies can't crown a winner.

Will retatrutide be cheaper or covered by insurance?

There's no approved retatrutide to price or cover yet. Lilly provides the drug at no cost through expanded access, but that doesn't establish what you'd pay for visits or tests. If you join a study or get expanded access, ask the team exactly which costs you'd pay. Our retatrutide insurance guide covers those questions.

Could my liver improve even if my weight loss has stalled?

This study can't predict what's happening in your liver during a plateau. In the study, liver fat tracked closely with weight loss and hit near its low point at about 20% weight loss. Ask your doctor how they'll check your liver, and don't change or combine medicines on your own.

Is retatrutide approved for fatty liver?

No. It isn't approved for anything. Lilly plans to apply in early 2027, and the uses it has named are obesity, knee arthritis pain, and sleep apnea.

Is compounded retatrutide an option?

No. The FDA says retatrutide can't be used in compounding under federal law. A vial sold as "research" or "compounded" retatrutide isn't backed by these study results.

Does retatrutide work for fatty liver if I have type 2 diabetes?

We don't know. People with type 2 diabetes were left out of the liver study. Ask your doctor which approved medicines fit both conditions.

Should I wait for retatrutide before getting liver care?

No. The research is a reason to ask good questions, not to put off care. Getting your scarring checked and treating what you have now matters more than waiting for a drug with no liver approval date.

Still not sure which GLP-1 path fits you? Take The RX Index's free Find My GLP-1 Path quiz — about 2 minutes, no signup.

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Sources

All checked October 24, 2026.

1. Sanyal AJ, et al. Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nature Medicine 2024;30:2037–2048. Published June 10, 2024. Full text read.
2. U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Content current as of Oct 1, 2026.
3. Eli Lilly and Company. TRIUMPH-2 and TRIUMPH-3 results and planned FDA submission. July 23, 2026.
4. Eli Lilly and Company. SYNERGY-Outcomes study page. NCT07165028.
5. ClinicalTrials.gov. NCT07165028, SYNERGY-Outcomes. Record updated Oct 8, 2026.
6. Lilly Medical. Is there an expanded access program for retatrutide? Last reviewed Aug 26, 2026.
7. FDA. Wegovy prescribing information. Revised June 2026.
8. FDA. Rezdiffra prescribing information. Revised July 2026.
9. Sanyal AJ, et al. Phase 3 Trial of Semaglutide in Metabolic Dysfunction–Associated Steatohepatitis. New England Journal of Medicine 2025;392:2089–2099. Published April 30, 2025; updated May 19, 2025. Full paper.
10. American Association for the Study of Liver Diseases. Noninvasive assessment of patients with MASLD.
11. Victoria Department of Health. Toxicity linked to unapproved peptide retatrutide. Issued June 19, 2026.
12. The RX Index. How Find My GLP-1 Path works.
13. National Capital Poison Center. Get help for a poisoning.
14. NHS. Cirrhosis: symptoms and when to seek help. Reviewed February 10, 2025.
15. National Institute of Diabetes and Digestive and Kidney Diseases. Weight loss and fatty liver. Reviewed April 2021; used here for weight-loss evidence, not current drug approvals.
16. National Institute of Diabetes and Digestive and Kidney Diseases. Dieting and gallstones. Reviewed November 2017.
17. Harrison SA, et al. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis. New England Journal of Medicine 2024;390:497–509. Full paper.
18. Loomba R, et al. Tirzepatide for Metabolic Dysfunction-Associated Steatohepatitis with Liver Fibrosis. New England Journal of Medicine 2024;391:299–310. Published abstract.
19. Eli Lilly. Zepbound prescribing information and Mounjaro prescribing information. Both revised August 2026.
20. FDA. Understanding unapproved use of approved drugs: off-label use.