A new study from researchers in Germany suggests that hidden fat inside muscles may reveal important clues about a person’s heart and metabolic health.
Using artificial intelligence and MRI scans, scientists discovered that people with more fat hidden between their muscles were more likely to have high blood pressure, unhealthy cholesterol levels, and abnormal blood sugar levels—even if they believed they were healthy.
The findings were published in the journal Radiology and may help doctors detect hidden health risks much earlier in the future.
The study focused on something called intermuscular fat. This is fat that builds up inside and around muscles, especially deep inside the body. Unlike fat stored under the skin, this hidden fat cannot easily be seen from the outside. Researchers now believe it may play an important role in overall health.
Scientists have known for many years that muscles do more than help people move. Skeletal muscles also help control blood sugar, support energy use, regulate inflammation, and influence heart health. Because of this, muscle quality may be just as important as muscle size.
The research team was led by Dr. Sebastian Ziegelmayer, an associate professor and radiologist at the Technical University of Munich.
The scientists wanted to better understand how muscle composition relates to cardiometabolic health. Cardiometabolic health refers to conditions linked to the heart, blood vessels, metabolism, blood sugar, and cholesterol.
To carry out the study, the researchers analyzed MRI scans from 11,348 adults who had no known major health conditions. The participants were examined at five imaging centers. About 57% of the participants were men, and the median age was 43 years old.
All participants underwent whole-body MRI scans. MRI, which stands for magnetic resonance imaging, is a medical imaging method that creates detailed pictures of structures inside the body without using radiation.
The researchers focused on muscles located along the spine between the neck and pelvis. These muscles are known as paraspinal muscles and play an important role in posture and movement.
Using a deep learning computer model and a segmentation algorithm, the scientists were able to automatically measure two important features inside the muscles. One was the amount of intermuscular fat, and the other was the amount of lean muscle tissue.
In the past, measuring these features required time-consuming manual work by trained specialists. However, the new artificial intelligence system allowed researchers to analyze large numbers of MRI scans much more quickly and efficiently.
The researchers then compared the muscle findings with participants’ health information, including blood pressure, blood sugar, cholesterol levels, and physical activity.
The results were surprising because many participants who believed they were healthy actually showed hidden cardiometabolic risk factors during testing.
About 16.2% of participants had previously undiagnosed high blood pressure. Around 8.5% had abnormal blood sugar levels, and nearly 46% had unhealthy lipid levels. Lipids are fatty substances in the blood, including cholesterol and triglycerides.
The study found a clear pattern. The higher the amount of hidden fat inside muscles, the greater the risk of cardiometabolic problems.
Participants with more intermuscular fat were more likely to have high blood pressure, unhealthy blood sugar, and abnormal cholesterol patterns. These findings remained significant even after researchers adjusted for age, sex, physical activity, and study location.
At the same time, people with more lean muscle tissue generally had better metabolic health. However, an interesting difference appeared between men and women.
The protective effect of lean muscle mass was mainly observed in men. In women, the relationship was less clear.
Dr. Ziegelmayer explained that women’s muscle mass tended to remain stable until around ages 40 to 50. After that, there was a noticeable decline, which may be related to menopause and falling estrogen levels.
The study also highlighted the importance of physical activity. People who were less physically active tended to have more hidden fat and lower lean muscle mass. This suggests that regular exercise may help maintain healthier muscle composition and reduce hidden cardiometabolic risks.
Researchers believe the findings may eventually lead to a new type of imaging biomarker. A biomarker is a measurable sign inside the body that can help predict disease risk.
Because MRI scans are already widely used for many medical purposes, doctors may one day be able to use existing scans to uncover hidden health risks without needing extra tests.
For example, someone receiving an MRI for back pain or another issue could also receive information about muscle composition and possible metabolic risk. This may help doctors identify people who appear healthy by standard medical tests but may actually face increased risks for heart disease or diabetes.
The researchers believe this approach could become a powerful tool for early prevention. Finding hidden risks earlier may allow patients to make lifestyle changes before serious disease develops.
The study also highlights the growing role of artificial intelligence in medicine. Deep learning systems can analyze enormous amounts of medical data much faster than humans alone. Researchers hope these technologies will continue improving disease detection and personalized care.
Still, the researchers caution that more studies are needed before MRI muscle analysis becomes part of routine medical screening. The current study was observational, meaning it found links between muscle composition and disease risk but could not prove direct cause and effect.
Even so, the large number of participants and the strong associations found in the study make the results very important.
Overall, the findings suggest that hidden fat inside muscles may reveal much more about a person’s health than previously understood. Muscle composition may not only reflect fitness and strength, but also hidden risks involving blood pressure, blood sugar, cholesterol, and long-term heart health.
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The research findings were published in the journal Radiology.
Source: Technical University of Munich.
