The fat you can’t see could be shrinking your brain
How obesity affects the brain may depend on more than overall body weight. New research published on January 27
How obesity affects the brain may depend on more than overall body weight. New research published on January 27 in Radiology, the flagship journal of the Radiological Society of North America (RSNA), suggests that the location of fat in the body plays a major role in brain health and cognitive outcomes.
The study was led by researchers at The Affiliated Hospital of Xuzhou Medical University in Xuzhou, China. Using MRI scans, the team identified two previously unrecognized patterns of fat distribution that showed the strongest links to negative brain and cognitive changes. One pattern, called “pancreatic predominant,” is marked by unusually high fat levels in the pancreas compared with other parts of the body. The second, known as “skinny fat,” involves a high overall fat burden in people who do not appear severely obese by traditional standards.
Moving Beyond Weight and BMI
Earlier studies have already shown that obesity, especially excess visceral fat, is associated with poorer brain and cognitive health. However, this research takes a more detailed approach by examining how specific fat storage patterns relate to neurological risk, said study coauthor Kai Liu, M.D., Ph.D., an associate professor in The Affiliated Hospital’s Department of Radiology.
“Our work leveraged MRI’s ability to quantify fat in various body compartments, especially internal organs, to create a classification system that’s data-driven instead of subjective,” Dr. Liu said. “The data-driven classification unexpectedly discovered two previously undefined fat distribution types that deserve greater attention.”
Large-Scale Imaging Data Reveals New Patterns
To conduct the analysis, the researchers used imaging and health data from 25,997 participants in the UK Biobank. This large database combines anonymized MRI scans with information on physical measurements, demographics, disease markers, medical history, and lifestyle factors. By linking these data, the team was able to compare brain health outcomes across different fat distribution profiles.
Among all the patterns identified, the “pancreatic-predominant” and “skinny fat” profiles stood out. Both were strongly associated with gray matter loss, faster brain aging, cognitive decline, and a higher risk of neurological disease. These associations were observed in both men and women, although some differences between the sexes were noted.
High Pancreatic Fat Emerges as a Key Risk Factor
People with the “pancreatic-predominant” pattern showed a proton density fat fraction — an MRI marker that provides a precise estimation of fat concentration in tissue — of about 30 percent in the pancreas.
“This level is about two to three times higher than that of other fat distribution categories, and it can be up to six times higher than that of lean individuals with low overall fat,” Dr. Liu said. “Additionally, this group tends to have a higher BMI and overall body fat load.”
Despite these elevated pancreatic fat levels, liver fat was not significantly higher in this group compared with other profiles. According to Dr. Liu, the combination of high pancreatic fat and relatively low liver fat represents a distinct pattern that is often missed in clinical settings.
“In our daily radiology practice, we often diagnose ‘fatty liver,'” Dr. Liu said. “But from the perspectives of brain structure, cognitive impairment and neurological disease risk, increased pancreatic fat should be recognized as a potentially higher-risk imaging phenotype than fatty liver.”
The Hidden Risks of “Skinny Fat”
The “skinny fat” profile showed a different pattern. Individuals in this group carried high levels of fat across most areas of the body, except for the liver and pancreas. Unlike people with more evenly distributed obesity, this fat tended to accumulate in the abdominal region.
“Most notably, this type does not fit the traditional image of a very obese person, as its actual average BMI ranks only fourth among all categories,” explained Dr. Liu. “The increase is perhaps more in fat proportion. Therefore, if one feature best summarizes this profile, I think, it would be an elevated weight-to-muscle ratio, especially in male individuals.”
Implications for Brain Health and Future Research
The study focused specifically on how fat distribution relates to neurological and cognitive risks. Dr. Liu emphasized that further research is needed to understand how these patterns may influence other health outcomes, including cardiovascular and metabolic disease.
Recognizing different fat distribution types could help health care providers offer more personalized guidance and earlier interventions aimed at protecting brain health. As Dr. Liu explained, “Brain health is not just a matter of how much fat you have, but also where it goes.”
