“If you take care of your liver, then your liver will take care of your muscles.” I doubt that’s something your mother ever told you. But it’s true! And so is the reverse – paying attention to the health and strength of your muscles will likewise make your liver healthier.
This is because both the liver and the skeletal muscles (the muscles attached to your bones that participate in voluntary movements) play a role in your overall metabolism. Skeletal muscle does this by taking up, storing, and releasing glucose as necessary.
Skeletal muscle also stores amino acids that can be distributed to the liver or elsewhere in the body when there is an increased demand for protein synthesis or energy. The liver also stores glucose as glycogen and can transform nutrients like sugar into fat, it can direct peripheral tissues to burn or store fat, and it can take up and distribute amino acids on demand. These coordinated metabolic activities create a sort of chemical communication between the liver and muscles, with each knowing the other’s activity and needs.
Enter the average American adult – sedentary, eats too much fatty food, is overweight, and drinks alcohol – and you encourage the situation known as fatty liver – which is exactly what it sounds like – a deposition of fat in the liver.
As many as 30 percent of U.S. adults might have this condition – non-alcoholic fatty liver disease, or NAFLD. That’s more than 100 million people! NAFLD is dangerous because it can lead to fibrosis, cirrhosis, and even liver cancer. NAFLD is the number one liver disease in the United States, and it is estimated that NAFLD will soon be the number one reason for needing a liver transplant.
So how can our muscles help prevent NAFLD? Regular exercise has been shown in numerous studies to improve the sensitivity of our cells to insulin, which makes our tissues more metabolically efficient, reduces the amount of free glucose in the bloodstream, and reduces the amount of free fatty acids in the blood.
Each of these consequences of regular exercise – and it doesn’t seem to matter whether it’s aerobic exercise or strength training (weightlifting, etc.) – improves liver function and reduces the amount of fat being deposited in the liver. Diet modification further increases this response.
When NAFLD causes the liver to work inefficiently, our skeletal muscles suffer, because they try to make up for the liver’s inability to do its normal job. The muscles release amino acids and glucose into the bloodstream, which causes muscle to waste. Muscle loss is a common feature of NAFLD (again, that’s as many as 30 percent of us).
The good news here is that the current NAFLD situation in the United States is mostly reversible. Adopting a healthy diet (particularly the Mediterranean diet), regularly exercising (4-5 times a week), and losing weight can reverse fatty liver. The liver is a superb organ that can regenerate and heal, but you have to give it a chance. Be good to your liver and your liver will be good to your muscles, and you.
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- Smart N, King N, McFarlane J, et al. Effect of exercise training on liver function in adults who are overweight or exhibit fatty liver disease: a systematic review and meta-analysis. Br J Sports Med 2018;52:831-843.
- Bandt J, Jegatheesan P, Tennoune-El-Hafaia N. Muscle loss in chronic liver diseases: the example of nonalcoholic liver disease. Nutrients 2018;10:1-11.
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- van der Windt D, Sud V, Zhang H, et al. The effects of physical exercise on fatty liver disease. Gene Expr 2018;18:89-101.