From the Guidelines
Obesity is a significant cause of borderline elevated ALT levels, primarily due to non-alcoholic fatty liver disease (NAFLD), as supported by the most recent evidence from 2023 1. The relationship between obesity and elevated liver enzymes is well-established, with a dose-response pattern observed, meaning the more severe the obesity, the higher the likelihood of ALT elevation. According to the American College of Radiology, hepatocellular injury causes the release of ALT and AST in serum, and an increase in ALT is directly linked to hepatocyte injury, which can be caused by fatty liver disease, among other conditions 1. Key points to consider include:
- NAFLD is the most common liver disease in first-world countries, with a prevalence of 20% to 30% in the general population, increasing to 70% with obesity and 90% with diabetes mellitus 1.
- The AST:ALT ratio is generally <1 in metabolic disease-related fatty liver, which is often associated with obesity 1.
- Weight loss through dietary changes and increased physical activity is the most effective treatment for obesity-related ALT elevation, with even modest weight reduction of 5-10% significantly improving liver enzyme levels and reducing liver fat content.
- Regular monitoring of liver enzymes is crucial during weight loss efforts to track improvement, and additional testing such as ultrasound or other imaging may be recommended to assess the degree of fatty liver.
From the Research
Borderline Elevated ALT Due to Obesity
- The relationship between obesity and elevated alanine aminotransferase (ALT) levels has been studied in various research papers 2, 3, 4.
- A study published in the Journal of Pediatric Gastroenterology and Nutrition found that the prevalence of elevated ALT in adolescents was 16.5% overall and 39.5% among those with obesity 2.
- The study also found that Hispanic ethnicity, age, male sex, and higher body mass index (BMI) were independent predictors of elevated ALT 2.
- Another study published in Hepatology Communications defined the upper reference limits (URLs) of ALT levels and found that male sex, BMI, glucose, lipids, ferritin, hypertension, and younger age were independent ALT predictors 4.
- The study also found that updated URLs were able to better predict liver disease, including steatosis and significant fibrosis, in individuals with dysmetabolism 4.
- While there is no direct evidence that borderline elevated ALT is solely due to obesity, the studies suggest that obesity is a significant risk factor for elevated ALT levels 2, 4.
- Other factors, such as insulin resistance, dyslipidemia, and metabolic syndrome, may also contribute to elevated ALT levels in individuals with obesity 3, 5, 6.