As there are not yet any approved pharmacotherapies for NAFLD, although there are a lot of ongoing clinical trials in this area, exercise and diet are the key recommendations made for improving fatty liver disease.
But how much exercise do you have to do to make a difference?
This is research that came from the UK on the Biobank cohort which who wore an accelerometer for 7 days to estimate exactly how active they were. One of the key limitations in a lot of exercise studies to date is they have been small and/or relied on questionnaires to assess exercise.
This study was very large looking at the data for 96,688 participants
The effects of exercise are independent of fat loss.
Key Messages
How much does exercise help NAFLD?
An increase of 2,500 steps per day was associated with:
47% reduction in NAFLD development
89% reduction in liver-related death for people who were known to have liver disease
69% reduction in the progression to cirrhosis for people known to have liver disease
The effect of exercise in reducing liver disease development is very stiking for people with type 2 diabetes but not as linear. While there was a large reduction in the overall proportion of liver disease it was only in the most active group who saw this benefit.
To reduce their risk of developing liver disease a person with type 2 diabetes needs to do 12,000 steps per day (the equivalent to ~3 hours of walking).
Why does exercise make a difference to NAFLD?
The mechanisms that cause the progression of NAFLD are not yet understood but we know that after the accumulation of intrahepatic fat some people go on to develop the necroinflammation in this fat which is called nonalcoholic steatohepatitis (NASH), and these patients with the inflammatory form progress on to liver scarring.
There are likely a number of ways that exercise improves NAFLD. Beyond the obvious effects of losing weight exercise is able to directly reduce hepatic fat by increasing the clearance of low density lipoprotein (LDL) cholesterol from the liver.
Exercise improves peripheral insulin sensitivity, although it doesn’t improve hepatic insulin sensity.
Exercise has been shown to reduce chronic inflammation and improve immune function.
References
Schneider, C. V., Zandvakili, I., Thaiss, C. A. & Schneider, K. M.. Physical activity is associated with reduced risk of liver disease in the prospective UK Biobank cohort. JHEP Reports 3, 100263 (2021).
Romero-Gómez, M., Zelber-Sagi, S. & Trenell, M.. Treatment of NAFLD with diet, physical activity and exercise. Journal of Hepatology 67, 829–846 (2017).
1.Semmler, G., Datz, C., Reiberger, T. & Trauner, M.. Diet and exercise in NAFLD/NASH: Beyond the obvious. Liver International 41, 2249–2268 (2021).