A key factor impeding the ability of people with non-alcoholic fatty liver disease (NAFLD) to exercise may be that the disease causes an iron deficiency. Because iron is vital to the body’s energy-production capacity, people with a deficiency in the mineral may feel too tired to become active as a means of losing weight and mitigating the disease.

John Olynyk, MD, of the department of gastroenterology at the Fiona Stanley Fremantle Hospital Group in Perth, Australia, and colleagues conducted an analysis of participants of the Raine Study, a longitudinal investigation of disease development in 2,868 children in Western Australia, 14% of whom had NAFLD.

Published in Clinical Gastroenterology and Hepatology, Olyynk’s study focused on 390 girls and 458 boys at the time they were 17 years old. These participants were screened for what is known as their submaximal physical work capacity as well as their fatty liver status, iron levels and other measures of their blood and metabolism.

The young people with fatty liver disease had a lower physical work capacity than those without the disease, independent of their body mass index. This lower capacity was strongly associated with parameters suggesting that the body was not making enough iron for normal metabolism.

Additionally, the study found that people with NAFLD had lower cardiovascular fitness than those without the disease—a difference that was also likely driven by an iron deficiency.

"What is likely happening is that non-alcoholic fatty liver disease is impeding the body’s ability to provide adequate iron into the blood to fuel processes such as energy and blood cell production,” Olynyk said in a press release.

“To use an analogy, if you imagine the body as a car and iron as its fuel, what is likely happening is that there is plenty of iron, or fuel in the tank, but the non-alcoholic fatty liver disease has caused the fuel line to shrink, so not enough fuel can get to the engine.”

Olynyk concluded: “This research shows that it may be more effective to first focus on new ways to improve the availability of iron to the body, enabling diet and physical activity to have better and more sustained effects on weight and the severity of their non-alcoholic fatty liver disease.”

To read the study abstract, click here.

To learn more about fatty liver disease, click here.