Where body fat is stored may be more important for brain health than overall body weight. A new study published in Nature Mental Health suggests that people with the same body mass index (BMI) can face very different risks of brain aging depending on where fat accumulates throughout the body.
Although obesity has long been linked to a higher risk of dementia, researchers are increasingly focusing on body fat distribution rather than weight alone. The new findings indicate that visceral fat—the fat surrounding internal organs—may be particularly harmful, potentially contributing to accelerated brain aging through metabolic and inflammatory processes.
Large-scale analysis of body fat and brain health
Researchers from The Hong Kong Polytechnic University analyzed data from more than 18,000 adults enrolled in the UK Biobank. The team combined detailed measurements of body fat with brain MRI scans and cognitive assessments to investigate how fat stored in different parts of the body relates to brain structure and function.
According to the researchers, this is the first large-scale multimodal study to systematically examine how regional fat deposits are associated with brain anatomy, neural connectivity, and cognitive performance. Rather than focusing solely on body weight or BMI, the researchers separately evaluated fat stored in the arms, legs, trunk, and around the abdominal organs.
Different fat deposits were linked to different brain changes
The analysis revealed that fat stored in different regions of the body was associated with distinct patterns of brain change. Arm fat, leg fat, trunk fat, and visceral fat each corresponded to alterations in different brain systems involved in movement, emotional regulation, memory, and brainstem function.
Lead author Anqi Qiu explained that fat stored in different parts of the body appears to follow unique pathways of brain aging that cannot be captured by BMI alone. As a result, two individuals with the same body weight may have substantially different levels of vulnerability to age-related brain changes depending on where their fat is concentrated.
Visceral fat showed the strongest association with white matter damage
Among all fat depots examined, visceral adipose tissue emerged as the strongest predictor of reduced brain integrity. It was the only type of fat directly associated with damage to white matter—the network of nerve fibers that connects different brain regions and allows information to travel efficiently throughout the brain.
Damage to white matter has been strongly linked to small vessel disease and vascular cognitive impairment, both of which increase the risk of dementia. The findings suggest that visceral fat may contribute to brain deterioration long before noticeable cognitive symptoms develop.
Inflammation may help explain the link
Although the study cannot establish exactly how visceral fat affects the brain, the researchers propose chronic low-grade inflammation as one possible mechanism. Compared with fat stored in other parts of the body, visceral fat is known to release higher levels of inflammatory molecules into the bloodstream.
This persistent systemic inflammation may eventually extend to the brain, promoting neuroinflammation and damaging white matter. The proposed explanation is consistent with previous research suggesting that disruptions in glucose metabolism and insulin regulation contribute to obesity-related brain aging.
What the findings could mean
Because body fat distribution is a modifiable risk factor, the findings may have important implications for preventing cognitive decline. The researchers suggest that lifestyle strategies aimed specifically at reducing visceral fat—including healthy eating, regular physical activity, and improving metabolic health—could potentially help preserve brain function over time.
The authors emphasize, however, that their study was observational and cannot demonstrate a direct cause-and-effect relationship. Nevertheless, they argue that the growing body of evidence supports visceral fat as a promising target for future strategies aimed at reducing the risk of neurodegenerative disease.
Further research will be needed to determine whether actively reducing visceral fat can slow or even reverse markers of brain aging. Long-term clinical trials tracking changes in brain imaging, cognitive performance, and inflammatory biomarkers will be essential for determining whether these associations translate into meaningful improvements in brain health.
Although additional research is required, the study adds to growing evidence that body composition may provide more meaningful information about dementia risk than body weight alone. Rather than focusing exclusively on the number shown on the scale, both clinicians and patients may ultimately benefit from paying closer attention to where body fat is stored and how it can be safely reduced.
