Bodybuilders often prioritise muscle development and performance, yet liver health remains a critical—and sometimes overlooked—aspect of long-term wellbeing. Do bodybuilders have fatty liver disease more often than the general population? The answer depends largely on training practices, dietary habits, and particularly the use of performance-enhancing substances. Whilst natural bodybuilding with sound nutrition typically supports metabolic health, certain practices—including anabolic steroid use, extreme caloric restriction, and contaminated supplements—can significantly increase hepatic stress. Understanding these risks enables bodybuilders to protect liver function whilst pursuing their physique goals, as fatty liver disease often develops silently before symptoms emerge.

Understanding Fatty Liver Disease in Athletes

Fatty liver disease, medically termed hepatic steatosis, occurs when excess fat accumulates in liver cells. It is defined as steatosis affecting more than 5% of hepatocytes on histology, or more than 5% liver fat content on imaging such as MRI. This condition exists in two primary forms: non-alcoholic fatty liver disease (NAFLD) and alcohol-related fatty liver disease. NAFLD has become increasingly prevalent in the UK; according to NHS data, up to one in three adults may have early-stage NAFLD.

The liver performs over 500 vital functions, including metabolising nutrients, filtering toxins, and producing proteins essential for blood clotting. When fat accumulates excessively, simple steatosis may progress to non-alcoholic steatohepatitis (NASH), characterised by inflammation and liver cell damage. Left unmanaged, this can advance to fibrosis, cirrhosis, or hepatocellular carcinoma. (Note: some professional bodies now use the terms MASLD—metabolic dysfunction-associated steatotic liver disease—and MASH, though NHS and NICE resources commonly continue to use NAFLD and NASH.)

Traditionally, fatty liver disease has been associated with obesity, type 2 diabetes, and metabolic syndrome. However, certain athletic populations, including bodybuilders, may face specific risk factors. These can include extreme dietary practices, supplement use, and—most significantly—performance-enhancing substances that impact hepatic metabolism.

Athletes often assume their fitness protects them from metabolic diseases, yet liver health depends on multiple factors beyond cardiovascular fitness. Insulin resistance, rapid weight fluctuations, very low body fat percentages, and certain training or dietary practices may all influence hepatic fat accumulation. Understanding these mechanisms is essential for bodybuilders seeking to optimise both performance and long-term health, as fatty liver disease often develops silently without obvious symptoms until significant damage has occurred.

Do Bodybuilders Have Higher Risk of Fatty Liver?

The relationship between bodybuilding and fatty liver disease is complex. Natural bodybuilders who maintain healthy training and nutrition practices do not necessarily face elevated risk compared to the general population. In fact, regular resistance training and maintaining lean muscle mass typically improve insulin sensitivity and metabolic health, which are protective factors against NAFLD. Evidence suggests that resistance exercise can improve markers of liver health in individuals with or at risk of NAFLD.

However, certain bodybuilding practices may increase hepatic stress. Extreme caloric restriction during cutting phases can trigger rapid mobilisation of fat stores, potentially overwhelming the liver's capacity to process fatty acids. Severe energy restriction may lead to starvation-associated hepatic steatosis, and rapid refeeding can transiently increase liver fat content—distinct from the life-threatening electrolyte disturbances of true refeeding syndrome, which occurs in severely malnourished individuals. Similarly, very high protein intakes—often exceeding 2.2 grams per kilogram of body weight—require substantial hepatic processing, though current evidence does not establish that dietary protein alone causes fatty liver in healthy individuals.

Rapid weight cycling between bulking and cutting phases may also pose risks. Some research suggests that repeated cycles of weight gain and loss can promote insulin resistance and metabolic dysfunction, both risk factors for NAFLD, though more evidence is needed. Bodybuilders who maintain extremely low body fat percentages year-round (below 6–8% for men) may experience hormonal disruptions that could affect lipid metabolism.

The most significant risk factor, however, relates to performance-enhancing drug use. Bodybuilders using anabolic-androgenic steroids, growth hormone, or insulin face substantially elevated risks of hepatotoxicity and fatty liver development. Studies have documented liver abnormalities in a significant proportion of steroid-using athletes, though the severity varies considerably based on the compounds used, dosages, and duration of use. Overall risk in bodybuilders therefore depends heavily on whether anabolic agents are used, alongside individual metabolic factors such as alcohol intake, pre-existing insulin resistance, and type 2 diabetes.

Anabolic Steroids and Liver Health in Bodybuilding

Anabolic-androgenic steroids (AAS) represent the most significant hepatotoxic risk in bodybuilding populations. These synthetic derivatives of testosterone exert profound effects on liver function through multiple mechanisms. Oral anabolic steroids, particularly 17-alpha-alkylated compounds such as methandrostenolone, stanozolol, and oxymetholone, are especially hepatotoxic due to their chemical modification, which allows survival through first-pass hepatic metabolism.

These substances can cause several forms of liver injury. Cholestatic hepatitis, characterised by impaired bile flow, commonly occurs with oral steroid use, manifesting as jaundice, itching, and elevated liver enzymes. Hepatocellular injury, where liver cells sustain direct damage, may also develop. More concerning are reports of peliosis hepatis—blood-filled cysts within the liver—and hepatic adenomas, benign tumours that carry risks of rupture and haemorrhage. Rare cases of hepatocellular carcinoma have been documented in long-term steroid users.

Injectable steroids generally pose lower hepatotoxic risk than oral formulations, though they are not without concern. High doses or prolonged use can still elevate liver enzymes and contribute to metabolic dysfunction. The practice of 'stacking' multiple compounds simultaneously, common in bodybuilding circles, exponentially increases hepatic stress.

Insulin resistance induced by AAS use represents another pathway to fatty liver development. Steroids can impair glucose metabolism and promote visceral fat accumulation despite low subcutaneous body fat. In the UK, anabolic steroids are Class C controlled drugs under the Misuse of Drugs Act 1971 and Misuse of Drugs Regulations 2001; supply without prescription is illegal. Additionally, selective androgen receptor modulators (SARMs) and 'prohormones' sold online are unlicensed medicines and have been associated with liver injury; these should be avoided.

Healthcare professionals should maintain non-judgemental communication with patients using these substances to facilitate harm reduction and appropriate monitoring of liver function. Confidential support is available through your GP, local drug and alcohol services, the NHS anabolic steroid misuse page, and FRANK.

Protein Supplements and Fatty Liver: What the Evidence Shows

Protein supplements—including whey, casein, and plant-based powders—are ubiquitous in bodybuilding nutrition. Concerns occasionally arise regarding their impact on liver health, particularly given the high protein intakes common in this population. Current evidence suggests that protein supplements themselves do not directly cause fatty liver disease in healthy individuals with normal liver function.

The liver plays a central role in amino acid metabolism, deamination, and urea synthesis. Whilst high protein intake increases hepatic workload, healthy livers possess substantial functional reserve to manage this demand. Studies examining protein intakes up to 2.2 grams per kilogram of body weight—well above general population recommendations—have not demonstrated hepatotoxicity in individuals without pre-existing liver disease.

However, several important caveats exist. Contaminated or adulterated supplements pose genuine risks. Testing by regulatory bodies has occasionally identified undeclared anabolic steroids, stimulants, or heavy metals in sports supplements, particularly those purchased from unregulated online sources. These contaminants, rather than protein itself, may cause liver injury. In the UK, food supplements are overseen by the Food Standards Agency (FSA); the FSA advises purchasing supplements only from reputable sources and checking online guidance on safe purchasing. UK Anti-Doping (UKAD) provides advice for athletes on contamination risks and recommends choosing products that have been batch-tested by reputable programmes such as Informed-Sport.

Individuals with existing liver disease, including cirrhosis, should seek specialist advice. Current UK guidance does not recommend routinely restricting protein in cirrhosis; in fact, adequate protein intake (often 1.2–1.5 g/kg/day) is usually advised, with support from a dietitian, unless clinically contraindicated. Additionally, some protein supplements contain added ingredients—such as high-dose vitamins, herbal extracts, or proprietary blends—that may carry hepatotoxic potential. Green tea extract, for instance, has been associated with rare cases of acute liver injury when consumed in concentrated supplement form, as noted by the European Food Safety Authority (EFSA). Bodybuilders should prioritise whole food protein sources where possible, exercise caution with high-dose extracts and multi-ingredient proprietary blends, and consult healthcare professionals before using multiple supplements concurrently.

Recognising Symptoms and Getting Tested

Fatty liver disease typically develops silently, with most individuals experiencing no symptoms during early stages. This asymptomatic nature makes the condition particularly insidious, as significant hepatic fat accumulation and even early fibrosis can occur before any clinical manifestations appear. Bodybuilders may be especially prone to dismissing subtle symptoms, attributing them to training intensity or dietary changes.

When symptoms do emerge, they are often non-specific. These may include persistent fatigue disproportionate to training load, vague right upper quadrant discomfort or fullness, and unexplained weight changes. As the condition progresses to NASH or fibrosis, additional features may develop: jaundice (yellowing of skin and eyes), dark urine, pale stools, easy bruising, and peripheral oedema (swelling). Seek urgent medical assessment if you develop new jaundice, confusion or drowsiness, vomiting blood or black stools, rapidly increasing abdominal swelling, or severe right upper quadrant pain with fever.

Liver function tests (LFTs) represent the first-line investigation for suspected hepatic disease. These blood tests measure enzymes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (GGT), alongside bilirubin and albumin levels. Elevated transaminases (ALT and AST) suggest hepatocellular injury, though normal LFTs do not exclude fatty liver disease.

According to NICE guidance (NG49), individuals with persistent LFT abnormalities or risk factors for NAFLD should undergo further assessment. NICE does not recommend screening the general population for NAFLD. If NAFLD is suspected or confirmed, the FIB-4 score (calculated from age, ALT, AST, and platelet count) should be used first-line to assess the likelihood of advanced fibrosis. If FIB-4 suggests possible advanced fibrosis, the Enhanced Liver Fibrosis (ELF) test or transient elastography may be used for further risk stratification. Transient elastography (e.g., FibroScan) measures liver stiffness as a marker of fibrosis; when available, the controlled attenuation parameter (CAP) can estimate the degree of hepatic steatosis. Ultrasound scanning can detect moderate to severe hepatic steatosis, though it may miss mild cases.

Bodybuilders should not routinely request baseline or periodic LFTs without clinical indication. If you have symptoms, risk factors (such as type 2 diabetes, obesity, or use of performance-enhancing substances), or abnormal liver tests, consult your GP for appropriate assessment. Adults aged 40–74 in England may be eligible for an NHS Health Check, which includes cardiovascular and metabolic risk assessment. Those using performance-enhancing substances should engage openly with their GP or local drug and alcohol services to enable appropriate monitoring and harm reduction, though specific monitoring intervals should be individualised based on clinical need.

Protecting Your Liver While Bodybuilding

Liver health optimisation should be integral to any bodybuilding programme, balancing performance goals with long-term wellbeing. Several evidence-based strategies can minimise hepatic stress whilst supporting training objectives.

Avoid anabolic steroids and performance-enhancing drugs. This represents the single most important protective measure. For those currently using or considering these substances, honest discussion with a healthcare professional enables harm reduction through appropriate monitoring and support for cessation. Confidential support is available through your GP, local drug and alcohol services, the NHS anabolic steroid misuse page, and FRANK. If injecting, access to needle and syringe programmes can reduce additional harms.

Moderate protein intake appropriately. Whilst higher protein supports muscle synthesis, intakes exceeding 2.2 grams per kilogram of body weight offer minimal additional benefit for most bodybuilders. Prioritise whole food sources—lean meats, fish, eggs, legumes, and dairy—over excessive supplement reliance. Distribute protein across multiple meals to optimise utilisation and reduce acute hepatic load.

Avoid extreme dietary practices. Gradual caloric deficits during cutting phases (300–500 kcal below maintenance) protect metabolic health better than aggressive restriction. Maintain adequate carbohydrate intake to support hepatic glycogen stores and prevent excessive fat mobilisation. Include healthy fats from sources such as oily fish, nuts, and olive oil, which support overall metabolic function.

Limit alcohol consumption according to UK Chief Medical Officers' low risk drinking guidelines: no more than 14 units weekly, spread across several days with regular alcohol-free periods. Combining bodybuilding supplements with alcohol compounds hepatic stress.

Exercise caution with supplements. Purchase only from reputable manufacturers. Check the Food Standards Agency guidance on buying food supplements online. UK Anti-Doping (UKAD) advises athletes to choose products that have been batch-tested by reputable programmes such as Informed-Sport to reduce contamination risk. Avoid products with proprietary blends, excessive stimulants, or unverified ingredients. Be particularly wary of supplements claiming dramatic results, as these may contain undeclared substances.

Engage with your GP based on individual risk. Do not request routine blood tests without clinical indication. If you have risk factors for liver disease (such as type 2 diabetes, obesity, metabolic syndrome, or use of hepatotoxic substances), discuss appropriate assessment with your GP. Adults aged 40–74 in England are eligible for an NHS Health Check, which includes cardiovascular and metabolic screening. If experiencing persistent fatigue, abdominal discomfort, or other concerning symptoms, seek prompt medical evaluation rather than attributing everything to training stress. Early intervention can prevent progression from simple steatosis to more serious liver disease.

Report suspected side effects. If you experience suspected adverse effects from any medicine (including anabolic agents) or herbal product, report them via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk or search for 'Yellow Card' in the Google Play or Apple App Store.

Frequently Asked Questions