What Is Fatty Liver Disease?
Fatty liver disease occurs when excess fat accumulates in the liver.
The newer medical terminology distinguishes metabolic dysfunction-associated steatotic liver disease (MASLD) from other causes of liver disease.
MASH is a more active form of MASLD. It involves:
- Fat accumulation in the liver
- Liver-cell injury
- Inflammation
- Possible progression to fibrosis
Fibrosis means scar tissue has developed in the liver. As fibrosis becomes more advanced, the risk of serious liver complications increases.
MASH is closely associated with metabolic conditions such as obesity, insulin resistance, and type 2 diabetes.
Why MASH Matters
Fatty liver can exist without obvious symptoms. A person may feel completely well while changes are occurring inside the liver.
For some patients, MASH can gradually progress to more significant fibrosis. Advanced fibrosis is associated with a higher risk of liver-related complications and mortality.
MASH is also closely connected with cardiovascular and metabolic health. Patients may have several conditions at the same time, including:
- Obesity
- Type 2 diabetes
- Insulin resistance
- High cholesterol
- High blood pressure
- Cardiovascular disease
This means liver health cannot always be considered separately from weight and metabolic health.
How Does Semaglutide Relate to Fatty Liver?
Semaglutide is a GLP-1 receptor agonist that affects pathways involved in appetite, blood sugar regulation, and energy balance.
It is already used for certain patients with type 2 diabetes and overweight or obesity. Previous research has shown that semaglutide can support weight loss and improve several metabolic measures.
The ESSENCE trial investigated whether these effects could also translate into improvements in the liver itself.
Importantly, the study assessed liver tissue using biopsies rather than relying only on weight or blood tests. This allowed researchers to evaluate whether the inflammation and fibrosis associated with MASH had changed.
What Was the ESSENCE Trial?
ESSENCE is an ongoing phase 3, multicentre, randomised, double-blind, placebo-controlled trial.
The study enrolled 1,197 patients with biopsy-confirmed MASH and fibrosis stage 2 or 3.
For the interim analysis, researchers reported results from the first 800 patients who had completed 72 weeks of treatment:
- 534 received semaglutide 2.4 mg
- 266 received placebo
The overall trial is designed to continue for 240 weeks, with later results intended to evaluate longer-term clinical outcomes, including cirrhosis-free survival.
What Did the Study Find About MASH?
One of the main outcomes was resolution of steatohepatitis without worsening of liver fibrosis.
After 72 weeks:
- 62.9% of patients receiving semaglutide achieved this outcome
- 34.3% of patients receiving placebo achieved it
The estimated difference between the groups was 28.7 percentage points.
This means that significantly more patients in the semaglutide group showed resolution of the inflammatory liver disease without their fibrosis becoming worse.
However, resolution of MASH is not the same as proving that long-term liver complications have been prevented. Those longer-term outcomes are still being studied.
Did Semaglutide Reduce Liver Fibrosis?
The study also looked at whether liver fibrosis itself decreased without worsening of steatohepatitis.
After 72 weeks:
- 36.8% of patients in the semaglutide group showed a reduction in fibrosis
- 22.4% in the placebo group showed a reduction
The estimated difference was 14.4 percentage points.
This is an important finding because fibrosis is a key factor in determining the long-term risk associated with metabolic liver disease.
The researchers also reported that 32.7% of patients receiving semaglutide achieved both MASH resolution and fibrosis reduction, compared with 16.1% receiving placebo.
What About Weight Loss?
Weight loss was another important finding.
At week 72:
- Average body-weight reduction with semaglutide was 10.5%
- Average reduction with placebo was 2.0%
The estimated difference between groups was 8.5 percentage points.
This is relevant because excess body weight and metabolic dysfunction are closely connected with fatty liver disease.
However, the liver findings cannot simply be reduced to weight loss alone. The researchers observed changes in liver-related measures alongside improvements in metabolic health, suggesting that multiple pathways may be involved.
What Happened to Liver Tests?
The trial also evaluated several non-invasive measures associated with liver health.
Researchers reported improvements with semaglutide in measures including:
- Enhanced Liver Fibrosis (ELF) score
- Liver stiffness
- FibroScan-AST (FAST) score
- PRO-C3
- Gamma-glutamyltransferase
- AST and ALT levels
Changes in aminotransferase levels were already apparent at 12 weeks.
At week 72, 55.8% of patients receiving semaglutide achieved a decrease in ELF score of at least 0.5, compared with 25.5% receiving placebo.
Similarly, 52.0% of semaglutide patients achieved a reduction in liver stiffness of at least 30%, compared with 30.3% of those receiving placebo.
These results are encouraging, but non-invasive markers should be interpreted alongside the patient’s overall clinical picture.
What Happened to Blood Sugar and Insulin Resistance?
MASH is closely connected with metabolic dysfunction.
In the ESSENCE trial, researchers observed improvements in:
- Glycaemic control
- Insulin resistance
- Blood pressure
- Triglycerides
- Cholesterol
- Inflammation markers
Among patients with type 2 diabetes, the improvement in insulin resistance appeared somewhat greater than among those without diabetes after excluding insulin use.
These findings reinforce the connection between liver health and metabolic health.
Treating one part of the problem may therefore need to be considered alongside management of weight, blood sugar, cholesterol, and other cardiovascular risk factors.
Who May Benefit From a Liver and Metabolic Health Assessment?
A liver health assessment may be useful for people who have risk factors for MASLD or MASH.
This may include people with:
- Overweight or obesity
- Type 2 diabetes
- Prediabetes
- Insulin resistance
- High triglycerides
- High cholesterol
- High blood pressure
- Abnormal liver enzymes
- A history of fatty liver
- Increasing waist circumference
Not everyone with fatty liver has MASH or significant fibrosis. Further assessment may be needed to understand the severity of liver disease.
When Should You Consider a Liver Health Check?
You may consider speaking with a doctor if you have previously been told that you have fatty liver or have abnormal liver blood tests.
A medical review may also be appropriate if you have metabolic risk factors or are concerned about unexplained changes in your liver health.
Testing may include liver enzymes such as ALT and AST, metabolic blood tests, imaging, or non-invasive fibrosis assessment depending on the individual situation.
Some patients may need referral for specialist liver assessment, particularly if advanced fibrosis is suspected.
What a Doctor May Assess
A doctor-led approach may include:
- Medical consultation
- Weight and BMI assessment
- Waist circumference
- Blood pressure
- Medical and family history
- Alcohol intake
- Liver function tests
- Blood glucose and HbA1c
- Cholesterol and triglycerides
- Fibrosis risk assessment
- Ultrasound or other imaging if appropriate
- Review of current medications
- Weight-management options
- Follow-up guidance
The purpose is to understand the overall metabolic and liver-health picture rather than relying on one test.
Benefits and Key Points to Understand
The ESSENCE trial provides important new evidence about semaglutide and MASH.
Key findings include:
- More patients achieved MASH resolution with semaglutide
- More patients experienced fibrosis reduction
- Weight loss was greater with semaglutide
- Several metabolic markers improved
- Liver-related non-invasive measures also improved
- Gastrointestinal side effects were common
- Long-term clinical outcomes are still being studied
The results suggest that weight and metabolic management may play an important role in caring for patients with MASH.
Safety, Side Effects, and Important Considerations
As with other GLP-1 receptor agonist treatments, gastrointestinal symptoms were among the most common side effects reported in the ESSENCE trial.
At week 72, reported adverse events included:
- Nausea
- Diarrhoea
- Constipation
- Vomiting
- Decreased appetite
Nausea occurred in 36.2% of patients receiving semaglutide compared with 13.2% receiving placebo.
Serious adverse events occurred in 13.4% of participants in both groups. Adverse events leading to treatment discontinuation occurred in 2.6% of the semaglutide group and 3.3% of the placebo group.
Patients with liver disease should not start or change medication without medical assessment.
Important Limitations of the Research
The ESSENCE findings are important, but they should be interpreted in context.
The current publication reports an interim analysis at 72 weeks, not the final results of the trial.
The trial is continuing for up to 240 weeks, and later results are intended to evaluate clinical outcomes such as cirrhosis-free survival.
The study also enrolled patients with biopsy-confirmed MASH and fibrosis stage 2 or 3. Therefore, the findings should not automatically be applied to everyone with mild fatty liver.
The study was funded by Novo Nordisk, and several authors were employees of the company or reported relationships with pharmaceutical companies.
Why Doctor-Led Care Matters
Fatty liver can range from relatively mild disease to significant inflammation and fibrosis.
A patient may have elevated liver enzymes without advanced fibrosis, while another person may have significant liver scarring despite relatively few symptoms.
This is why treatment should not be based on weight alone.
A doctor can help determine:
- Whether fatty liver is present
- Whether fibrosis risk needs assessment
- Which blood tests are appropriate
- Whether imaging is needed
- Whether weight management could help
- Whether medication is suitable
- Whether referral to a liver specialist is needed
Book a Liver and Weight Management Consultation in Bangkok
If you have been told that you have fatty liver, have abnormal liver tests, or are concerned about weight and metabolic health, a medical assessment can help clarify your situation.
MedConsult Clinic provides doctor-led consultations in Bangkok, with health assessments and blood testing where appropriate.
If weight management and liver health are connected to your concerns, a doctor can help review your medical history, metabolic markers, and available treatment options.
Frequently Asked Questions
Can weight loss help fatty liver?
Weight loss can improve several metabolic factors associated with fatty liver. The amount of improvement varies between patients and depends on the severity and type of liver disease.
Does semaglutide treat MASH?
The ESSENCE trial found that semaglutide improved liver histologic outcomes in patients with MASH and fibrosis stage 2 or 3. However, the trial is ongoing, and long-term clinical outcomes are still being studied.
Can fatty liver cause symptoms?
Many people with fatty liver have few or no obvious symptoms. Liver disease can therefore sometimes be discovered through blood tests or imaging performed for another reason.
Do I need a liver biopsy to check for fatty liver?
Not always. Doctors may use blood tests, imaging, and non-invasive fibrosis assessments. A biopsy was required in the ESSENCE trial to confirm eligibility and measure the primary liver outcomes.
Can I take weight-loss medication if I have fatty liver?
It may be appropriate for some patients, but suitability depends on liver health, weight, medical history, current medications, and other risk factors. A doctor should assess you before treatment.
References
Sanyal AJ, Newsome PN, Kliers I, et al.
Phase 3 Trial of Semaglutide in Metabolic Dysfunction–Associated Steatohepatitis. New England Journal of Medicine. 2025;392:2089–2099.
https://doi.org/10.1056/NEJMoa2413258
Rinella ME, Lazarus JV, Ratziu V, et al.
A multisociety Delphi consensus statement on new fatty liver disease nomenclature. Journal of Hepatology. 2023;79:1542–1556.
Powell EE, Wong VW, Rinella M.
Non-alcoholic fatty liver disease. The Lancet. 2021;397:2212–2224.
European Association for the Study of the Liver, European Association for the Study of Diabetes, European Association for the Study of Obesity.
Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease. Diabetologia. 2024;67:2375–2392.
Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al.
AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77:1797–1835.