Hidden muscle fat may signal blood pressure and blood sugar issues

Fat stored deep within the muscles beside the spine may point to health concerns that standard body-weight checks can overlook. In an imaging study, higher levels of muscle fat were associated with undiagnosed high blood pressure, abnormal blood sugar, and unhealthy blood fat levels.

The results suggest that muscle quality, not just muscle size, may offer important clues about health. In the future, doctors could potentially extract more information from scans done for other medical reasons.

Researchers at the Technical University of Munich examined MRI scans from 11,348 adults enrolled in the German National Cohort. The study, published in Radiology, focused on people without known pre-existing conditions.

Muscle does more than support movement. It helps the body use glucose and manage energy, which makes changes in muscle tissue relevant to diabetes and cardiovascular health.

The researchers concentrated on the muscles running along the spine. These muscles help maintain posture and stabilise the body, but they can also hold fat between and within their tissue structures.

This intermuscular fat is different from the fat seen just under the skin. MRI can separate tissue types, allowing scientists to measure fat and active muscle more directly.

To efficiently process thousands of scans, the team used a deep-learning model. This type of artificial intelligence identifies patterns in images and can distinguish the muscle and fat regions needed for the analysis.

The participants had a median age of 43, and about 57% were men. Their scans came from five imaging centres, and the researchers compared the tissue measurements with blood pressure readings and laboratory results.

Previously unrecognised risk factors were common. More than 16% of participants had high blood pressure, about 8.5% had abnormal blood sugar, and nearly 46% had unhealthy lipid levels, meaning blood fats such as cholesterol and triglycerides.

Higher amounts of hidden muscle fat were linked to a worse overall health profile. The association remained even after the researchers accounted for factors such as age, sex, physical activity, and study location.

The findings also indicate that lean muscle and fat should be evaluated separately. A larger muscle does not necessarily mean its tissue composition is healthy, or that it carries the same implications in men and women.

Because this was an observational study, it cannot show whether muscle fat caused the problems or whether both were driven by the same underlying factors. It also does not prove that the scans can predict who will later develop a specific disease.

More research will be needed to define useful measurement thresholds and to test whether adding this information improves patient care. For now, the study suggests that medical images may reveal a deeper picture of health than a bathroom scale alone can provide.

Source: Technical University of Munich.