How obesity affects the brain may depend not only on total body weight. New research published on January 27 Radiologyflagship journal of the Radiological Society of North America (RSNA), suggests that body fat location plays a major role in brain health and cognitive outcomes.
The study was led by researchers from 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 characterized by unusually high levels of fat in the pancreas compared to other parts of the body. The second, known as “skinny fat,” involves a high total fat burden in people who do not appear severely obese by traditional standards.
Moving beyond weight and BMI
Previous studies have already shown that obesity, especially excess visceral fat, is associated with poorer brain and cognitive health. But this research takes a more detailed approach by examining how specific patterns of fat deposition relate to neurological risk, said study co-author Kai Liu, MD, Ph.D., associate professor in the Department of Radiology at The Affiliated Hospital.
“Our work used MRI’s ability to quantify fat in different body compartments, particularly internal organs, to create a classification system that is data-driven instead of subjective,” said Dr. Liu. “The data-driven classification unexpectedly discovered two previously undefined types of fat distribution that deserve more attention.”
Large-scale data reveals new patterns
To carry out the analysis, the researchers used imaging and health data from 25,997 participants in the UK Biobank. This large database combines anonymized MRI images with information on physical measurements, demographics, disease markers, medical history, and lifestyle factors. By linking this data, the team was able to compare brain health outcomes across different fat distribution profiles.
Among all the patterns identified, the “predominant pancreas” and “lean fat” profiles stood out. Both were strongly associated with loss of brain gray matter, faster brain aging, cognitive decline, and a higher risk of neurological disease. These associations were seen in both men and women, although some gender differences were noted.
High pancreatic fat is emerging as a key risk factor
People with the “predominant pancreas” pattern showed a proton density fat fraction — an MRI marker that provides an accurate estimate of tissue fat concentration — of about 30 percent in the pancreas.
“This level is about two to three times higher than other categories of fat distribution and can be up to six times higher than lean individuals with overall low body fat,” said Dr. Liu. “In addition, this group tends to have a higher BMI and total body fat burden.”
Despite these increased levels of pancreatic fat, liver fat was not significantly higher in this group compared to other profiles. According to Dr. Liu, the combination of high pancreatic fat and relatively low liver fat presents a distinct pattern that is often missed in the clinical setting.
“In our daily radiology practice, we often diagnose ‘fatty liver,'” said Dr. Liu. “But in terms of brain structure, cognitive impairment, and risk of neurological disease, increased pancreatic fat should be recognized as a potentially high-risk imaging phenotype rather than fatty liver.”
The Hidden Risks of “Skinny Fat”
The “lean fat” profile showed a different pattern. Individuals in this group carried high levels of fat in most areas of the body, with the exception of the liver and pancreas. Unlike people with more evenly distributed obesity, this fat tended to accumulate in the abdominal area.
“First of all, this type does not correspond to the traditional image of a very obese person, because his actual average BMI is only in fourth place among all categories,” explained Dr. Liu. “Perhaps the increase is more in fat ratio. So if one trait best sums up this profile, I think it would be an increased weight-to-muscle ratio, especially in men.”
Implications for brain health and future research
Specifically, the study looked at how fat distribution relates to neurological and cognitive risks. Dr. Liu stressed that more research is needed to understand how these patterns may affect other health outcomes, including cardiovascular and metabolic diseases.
Recognizing different types of fat distribution could help healthcare providers offer more personalized advice and earlier interventions aimed at protecting brain health. As explained by Dr. Liu: “Brain health isn’t just about how much fat you have, it’s also about where it goes.”
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