High levels of fat often accumulate deep within muscles and pose a danger to our health and well-being. Studies show that ‘myosteatosis’, the accumulation of fat in skeletal muscles, can raise the risk of death among otherwise healthy adults as much as type 2 diabetes and smoking.
A growing body of research identifies serious health dangers associated with myosteatosis, but unfortunately it often goes overlooked by physicians, who estimate body fat by relying only on body mass index (BMI). This evaluation fails to provide an accurate representation of body composition, and people with similar BMIs can have widely varying levels of health risks.
A new study by researchers at Louisiana State University in the United States tracked adverse health events such as heart attacks, strokes, and aneurysms during a follow-up period of about nine years. Ofthe nearly 9,000 healthy adults in the study, 507 died during the follow-up period. Myosteatosis, which was found to increase the risk of major adverse events, appeared in 55 percent of those who died during the follow-up period..
The researchers reported that excess muscle fat increased the absolute mortality rate at 10 years by 15 percent, more than for known risk factors for early death such as obesity (7%), fatty liver disease (8%) and muscle wasting (9%). Experts say that accumulation of fat in muscles increases with age and as muscles atrophy. While genetics may partly explain this fat accumulation, the specific cause of this is not precisely clear.
Previous research has linked muscle fat to several health risks. One study showed that high levels of intramuscular fat infiltration increased the risk of heart failure. Another study revealed that the amount of lean muscle a healthy person has in middle age is linked to their future risk of heart disease. Other studies have drawn a link between fatty muscles and poor outcome, including one which found that cancer patients diagnosed with myosteatosis had a 75 percent greater mortality risk than those without fatty muscles.
Other studies have assessed the effects of exercise alone on mitigating the severity of myosteatosis, and some studies have reported promising results. Overall, the findings indicate that exercise can significantly improve muscle quality in populations at risk of developing obesity, as well as in patients facing disabilities due to age-related gradual loss of muscle mass, strength and function.
Analysts evaluating the new study said that such a high death rate because of the elevated fat levels in muscles is really important and needs to get serious attention from the broader medical community, especially considering that the link between myosteatosis and higher risk of death was unrelated to age or obesity markers revealed by BMI. The new findings indicate that we need to rethink standards on assessing the health risks of muscle fat.
They note that abdominal CT or MRI scans provide a more accurate and thorough assessment of muscle fat than a mere BMI test. Currently available artificial intelligence (AI) programs can also enable medical professionals to extract more specific body-composition metrics from abdominal CT scans. A better understanding of the factors that regulate myosteatosis may lead to the development of novel therapies that influence healthy outcomes.
Researchers behind the study say that further studies will be needed to identify the specific physiological mechanisms that influence myosteatosis, and the processes that link this fat depot with insulin resistance. Studies will also need to help determine whether myosteatosis is solely a biomarker of poorer health status or whether it is causally associated with an increased risk of death.