Fatty Liver Disease: Prevention, Diagnosis and When to See a Doctor
Fatty liver disease is one of the most common liver conditions in the UK, and most people who have it do not know. Our editorial team explains how it develops, how it is diagnosed, what genuinely prevents it and which symptoms need a doctor.
What fatty liver disease is
Fatty liver disease means that fat makes up an abnormally large share of liver cells. The most common form is now called metabolic dysfunction-associated steatotic liver disease (MASLD), a term adopted in 2023 to replace the older "non-alcoholic fatty liver disease" (NAFLD).
The new name reflects the main drivers: excess body fat, especially around the abdomen, insulin resistance, type 2 diabetes, high blood pressure and abnormal blood lipids. Alcohol-related liver disease is a separate condition, although the two can coexist.
Estimates suggest that around a quarter of adults worldwide have some degree of fatty liver, and UK figures are broadly similar. Most people have no symptoms, which is why the condition is usually discovered by chance on a blood test or scan.
Athletes are not automatically protected. Lean people can develop MASLD, and some practices common in strength sport, such as extreme bulking diets, heavy alcohol intake or the use of certain anabolic agents, can add stress to the liver.
How the disease progresses
In many people fatty liver remains a stable, relatively benign state. In a proportion, fat accumulation triggers inflammation and cell injury, known as steatohepatitis (MASH). Over years this may lead to scarring (fibrosis), and in some cases to cirrhosis and liver cancer.
The degree of fibrosis is the most important predictor of long-term outcome. This is why doctors focus less on how much fat is present and more on whether scarring has developed.
Fatty liver is also closely linked with cardiovascular disease, which remains the leading cause of death in people with MASLD. Treating the liver therefore goes hand in hand with protecting the heart.
The encouraging message is that early stages respond well to lifestyle change, and even fibrosis can partially regress with sustained weight loss.
Prevention: what genuinely helps
Prevention relies on the same habits that protect metabolic health in general. The evidence is strongest for weight management and regular physical activity.
- Gradual weight loss: in a well-known Cuban cohort, losing 7–10% of body weight was associated with marked improvement in liver histology.
- Exercise: both aerobic and resistance training reduce liver fat, even with little change on the scales.
- Diet quality: a Mediterranean-style pattern, fewer sugar-sweetened drinks and less ultra-processed food.
- Alcohol: keeping within the UK Chief Medical Officers' low-risk guideline of 14 units a week, or less.
- Medicines and supplements: avoiding unnecessary hepatotoxic substances, including oral anabolic steroids and unregulated "liver detox" products.
For athletes, very rapid weight cuts and crash diets are not a solution: abrupt weight loss can temporarily worsen liver inflammation and raise the risk of gallstones.
No supplement has been proven to prevent or cure fatty liver. Products marketed for "liver support" should not distract from the measures listed above.
How it is diagnosed in the UK
Diagnosis usually starts in primary care. A GP may notice abnormal liver enzymes on routine blood tests, or fatty liver may be reported on an ultrasound done for another reason.
| Test | What it shows | Comment |
|---|---|---|
| Liver blood tests (ALT, AST, GGT) | Possible liver cell injury | Can be normal even when fatty liver is present |
| Ultrasound | Fat in the liver | Does not reliably assess scarring |
| FIB-4 score | Estimated risk of advanced fibrosis | Calculated from age, AST, ALT and platelets |
| ELF blood test | Markers of fibrosis | Recommended by NICE for people with NAFLD |
| Transient elastography (FibroScan) | Liver stiffness | Usually in specialist or community hepatology services |
| Liver biopsy | Definitive assessment | Reserved for uncertain or complex cases |
Strength athletes should mention heavy training and any supplement or drug use to their doctor, because intense exercise can raise AST and ALT temporarily and muscle mass affects some results.
Honesty about substance use matters: anabolic steroids and some other agents affect liver tests, and the doctor needs the full picture to interpret them.
When to see a doctor
Fatty liver usually causes no symptoms, so a check-up is worth considering if you have risk factors: a large waist, type 2 diabetes or prediabetes, high blood pressure, raised cholesterol or triglycerides, or a family history of liver disease.
Seek prompt medical attention if you notice yellowing of the skin or eyes, dark urine, pale stools, persistent itching, swelling of the abdomen or legs, easy bruising or confusion. These can indicate more advanced liver disease.
Anyone who has used oral anabolic steroids or high doses of unregulated supplements and has abdominal pain, jaundice or unusual tiredness should stop the substance and see a doctor urgently.
Follow-up intervals depend on the fibrosis risk. People with low risk may be reassessed every few years, while those with significant fibrosis need specialist care.
Editorial conclusions
Fatty liver disease is common, often silent and closely linked to metabolic health. The most important practical step is to know your risk factors and, if needed, ask your GP about fibrosis assessment rather than relying on liver enzymes alone.
Sustained weight loss, regular exercise and moderate alcohol intake remain the foundations of prevention and treatment. Supplements cannot replace them.
Athletes should avoid hepatotoxic substances and be open with doctors about what they take.
Related topics on our site: liver blood tests explained, the history of essential phospholipids, and how alcohol affects recovery.
References
- Rinella ME, Lazarus JV, Ratziu V, et al. A multisociety Delphi consensus statement on new fatty liver disease nomenclature. Hepatology. 2023;78(6):1966–1986.
- European Association for the Study of the Liver (EASL), European Association for the Study of Diabetes (EASD), European Association for the Study of Obesity (EASO). EASL-EASD-EASO Clinical Practice Guidelines for the management of non-alcoholic fatty liver disease. J Hepatol. 2016;64(6):1388–1402.
- National Institute for Health and Care Excellence. Non-alcoholic fatty liver disease (NAFLD): assessment and management. NICE guideline NG49. London: NICE; 2016.
- Younossi ZM, Koenig AB, Abdelatif D, et al. Global epidemiology of nonalcoholic fatty liver disease: meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology. 2016;64(1):73–84.
- Vilar-Gomez E, Martinez-Perez Y, Calzadilla-Bertot L, et al. Weight loss through lifestyle modification significantly reduces features of nonalcoholic steatohepatitis. Gastroenterology. 2015;149(2):367–378.
- Angulo P, Kleiner DE, Dam-Larsen S, et al. Liver fibrosis, but no other histologic features, is associated with long-term outcomes of patients with nonalcoholic fatty liver disease. Gastroenterology. 2015;149(2):389–397.
