Research shows how gender and age influence the fat content in muscles and bones

Researchers at UT Southwestern Medical Center have discovered sex-specific differences in the way fat accumulates in muscle and bone, revealing patterns that could inform new approaches to treating age-related diseases.

Their findings, published in Diagnosticsdescribe how fat infiltrates skeletal muscle and accumulates in subcutaneous tissue and bone marrow, revealing important differences between men and women shaped by age and body mass index (BMI).

“Musculoskeletal disorders are the leading cause of disability in the US, with dramatic consequences for quality of life and longevity,” said senior author Jimin Ren, Ph.D., associate professor at the Advanced Imaging Research Center (AIRC) and in Radiology at UT Zuidwestelijk. “This study identifies key contributors to muscle fat infiltration (MFI), a harmful accumulation of fat in skeletal muscle that can lead to muscle atrophy and dystrophy.”

The study analyzed magnetic resonance imaging (MRI) scans from 107 UTSW patients, 64 men and 43 women, aged 11 to 79 years, representing different ethnicities and a range of BMI. Focusing on the lower extremities, the team found that MFI increased significantly with age in women, but was more strongly correlated with body weight in men. In addition, the average thickness of subcutaneous fat in women was approximately twice as high (8.9 millimeters versus 4.3 mm). This fat increased with age in women but decreased in men, especially in non-obese individuals.

The researchers also observed a relationship between MFI and bone marrow cross-sectional area (BMA), highlighting the interdependence of musculoskeletal health. A weakened bone structure can facilitate the infiltration of fat into surrounding muscles, creating physical challenges that increase the risk of falls, fractures and metabolic disorders. These results suggest that maintaining overall musculoskeletal strength is essential for managing age-related conditions, especially in older adults.

“Skeletal muscle is the largest organ in the body by mass and plays a critical role in regulating glucose metabolism,” said Dr. Run. “When fat accumulates too much in the muscles, it can impair the muscles’ ability to process glucose, increasing the risk of insulin resistance and associated health problems such as obesity, heart failure, stroke, sarcopenia, osteoporosis, chronic kidney disease and type 2 diabetes. increases. “

The study sheds additional light on gender-specific health problems as people age. For example, in women, hormonal changes after menopause likely increase the risks of conditions such as sarcopenia (age-related loss of muscle mass and strength) and osteoporosis (which weakens bones). In men, the stronger correlation between body weight and fat infiltration highlights the importance of controlling obesity to protect muscle function.

The findings describe how gender, age and BMI influence fat distribution and provide insights for developing personalized strategies – including exercise regimens, nutritional advice and therapies – to promote musculoskeletal health and prevent age-related decline. Furthermore, said Dr. Ren, the study holds promise for clinical care by highlighting markers such as subcutaneous fat thickness, intramuscular fat and BMA, which can be used to screen and monitor muscle metabolic health and reduce the risk of sarcopenia and osteoporosis can be assessed non-invasively. .

“By linking fat infiltration in muscle to fat in bone marrow, the study highlights a potential avenue for dual-targeted therapies that support both muscle and bone,” said lead author Talon Johnson, Ph.D., a postdoctoral researcher in the AIRC. “Such an integrated perspective on bone and muscle health could contribute to the development of early interventions for metabolic and musculoskeletal disorders that become more common with aging.”