It is well established that excess visceral fat is harmful to health. The primary mechanism is likely that this tissue provokes chronic inflammation in a variety of ways, from increased cellular senescence to mimicking the signaling produced by infected cells. It is also well established that muscle tissue is protective in later life, however here the underlying mechanisms are less well understood. Muscle tissue is just as metabolically active as visceral fat, and generates a variety of signal molecules that alter the behavior of cells throughout the body, particularly following exercise. Cataloging these signals and their effects is an active area of ongoing research.
Researchers have found that a specific body profile - higher muscle mass combined with a lower visceral fat to muscle ratio - tracks with a younger brain age. Brain age is the computational estimation of chronological age from a structural MRI scan of the brain. Muscle mass, as tracked by body MRI, can be a surrogate marker for various interventions to reduce frailty and improve brain health, and brain age predicted by structural brain images can lend insight to Alzheimer's disease risk factors, such as muscle loss.
For the ongoing study, 1,164 healthy individuals (52% women) were examined with whole-body MRI. The mean chronological age of the participants was 55.17 years. The researchers combined MRI imaging with T1-weighted sequences, a technique that produces images where fat appears bright and fluid appears dark. This allows for optimal imaging of muscle, fat and brain tissue. A machine learning algorithm was used to quantify total normalized muscle volume, visceral fat (hidden belly fat), subcutaneous fat (fat under the skin) and brain age.
The researchers found that a higher visceral fat to muscle ratio was associated with higher brain age, while subcutaneous fat showed no significant association with brain age. Building muscle and reducing visceral fat are actionable goals. Whole-body MRI and brain-age estimates provide objective endpoints to design and monitor interventions, including programs or therapies under study that lower visceral fat while preserving muscle.
Link: https://www.rsna.org/media/press/2025/2614
View the full article at FightAging
