Researchers used AI to analyze whole-body MRI scans from over 66,000 participants to create a reference map of fat and muscle distribution in the human body, accounting for age, sex, and height.
"BMI does not reliably reflect a person's actual body composition." — Jakob Weiss, M.D., Ph.D., senior author
The study, published in Radiology, found that the quality and amount of skeletal muscle, along with visceral fat, are strong predictors of diabetes, major cardiovascular events, and mortality.
Key Details
- Participants: 66,608 individuals (mean age 57.7, 34,443 males, mean BMI 26.2) who underwent whole-body MRI as part of the UK Biobank and German National Cohort between April 2014 and May 2022.
- Metrics Measured: Subcutaneous adipose tissue, visceral adipose tissue, skeletal muscle, skeletal muscle fat fraction, and intramuscular adipose tissue. These were expressed as z-scores relative to age-, sex-, and height-adjusted norms.
- Analysis: Statistical analyses assessed the prognostic value of z-score categories (low, middle, high) for predicting diabetes, major adverse cardiovascular events, and all-cause mortality.
Results
- High visceral fat was associated with a 2.26-fold increased risk of diabetes.
- High intramuscular fat was associated with a 1.54-fold increased risk of major cardiovascular events.
- Low skeletal muscle was associated with a 1.44-fold higher all-cause mortality.
Key Takeaway
"It's not only how much muscle you have, but also the quality of that muscle." — Matthias Jung, M.D., first author
Tools Released
To support future research and clinical translation, the researchers released an open-source, web-based age-, sex-, and height-adjusted body composition z-score calculator.