Condition5 min read
Metabolic dysfunction-associated steatotic liver disease
MASLD
Fat builds up in the liver without alcohol being the cause. It usually has no symptoms, is linked to obesity, diabetes and high blood fats, and weight loss and a healthy lifestyle are the main treatment.
The NIDDK uses both the old and the new terms: NAFLD and NASH are the same as MASLD and MASH. In simple fatty liver (NAFL/MASLD) only fat accumulates, whereas in NASH/MASH there is inflammation and liver damage. The NHS states that most people with the condition stay at the first stage (fat without damage).
The NIDDK states that risk factors include obesity, metabolic syndrome and type 2 diabetes. The NHS adds polycystic ovary syndrome, high blood pressure and cholesterol, and age over 50. It is usually found by chance during other tests; blood tests and imaging (ultrasound) are done, and a biopsy may be needed to tell NAFL from NASH.
In one minute12
- What is it?
- Fat build-up in the liver not related to alcohol.
- Who is usually affected?
- People with obesity, type 2 diabetes, metabolic syndrome, or high blood fats and blood pressure.
- Acute or chronic?
- Many people stay at a stage without damage; some progress to inflammation and scarring.
- Main symptoms
- Often no symptoms; severe tiredness and discomfort in the upper right of the abdomen may appear.
- Red flags?
- No emergency warning sign is listed; see a doctor if in doubt or if you have risk factors.
- Preventable?
- Healthy weight, balanced diet and physical activity.
What is it?
Non-alcoholic fatty liver disease (NAFLD) is a condition in which fat builds up in the liver, and it has two types: NAFL (fatty liver) and NASH (non-alcoholic steatohepatitis), where there is fat with inflammation and liver damage. The NIDDK lists the new terms MASLD and MASH as alternative names for the same two conditions.
The NHS describes the condition as common and often linked to being overweight, usually treatable by lifestyle changes, and also calls it MASLD.
Causes
The sources do not identify a single cause; rather, factors that increase the likelihood, including obesity, metabolic syndrome and type 2 diabetes (NIDDK).
Risk factors
According to the NHS: being overweight, especially around the waist, a poor diet and lack of exercise, type 2 diabetes, polycystic ovary syndrome, high blood pressure and cholesterol, and age 50 or over.
Symptoms
Often no symptoms or few symptoms (NIDDK). If they appear: severe tiredness, a general feeling of being unwell, and discomfort under the ribs on the right side (NHS).
How is it diagnosed?
It is often found by chance during tests for another reason. The doctor reviews symptoms, measurements and alcohol intake, and may request blood tests and an ultrasound to rule out other liver diseases (NHS). The NIDDK mentions medical history, examination, tests, imaging and possibly a biopsy to tell NAFL from NASH.
Treatment
The treatment categories usually used are listed here; this is not a prescription. The doctor chooses the plan according to each person's condition; do not change any medicine or dose without a specialist.
The main recommendation is weight loss; it reduces fat, swelling and scarring in the liver (NIDDK). The NHS mentions a balanced diet, more than 150 minutes of activity a week, and weight reduction.
The NIDDK page states that no medicines have been approved to treat NAFLD/NASH, whereas the NHS says people with liver damage may need specialist care that includes medicines such as pioglitazone or vitamin E. Drug options may change, so consult the specialist doctor and do not start these substances without their supervision.
Follow-up
The NHS mentions annual tests and follow-up every two to three years to monitor progression.
Prevention
Eating a healthy diet and maintaining a suitable weight may help prevent it (NIDDK). According to the NHS, lifestyle changes prevent progression to more serious stages in most people with the condition.
When do you need urgent help?
See your doctor within days
- Risk factors (obesity, diabetes, high blood fats and blood pressure), or severe tiredness and upper right abdominal pain: see a doctor to assess the liver.2
Educational content only — no diagnosis, and no substitute for a clinician.
Common questions
Questions for your doctor
- Do I have fat only, or liver inflammation?
- How much weight do I need to lose?
- Do I need regular tests or a fibrosis scan?
- Do I have diabetes or blood fats that need treatment?
References
- 1NIDDK / NIH. Metabolic dysfunction-associated steatotic liver disease (MASLD) / NAFLD. www.niddk.nih.gov/health-information/liver-disease/nafld-nashHealth agencies & guidelines · Accessed 2026-10-04
- 2NHS. Non-alcoholic fatty liver disease (NAFLD). www.nhs.uk/conditions/non-alcoholic-fatty-liver-disease/Health agencies & guidelines · Accessed 2026-10-06
Review status: Edited content · Last updated:
Change log
- — Page created.
Educational content only — no diagnosis, and no substitute for a clinician.