Excess body fat is widely recognised as a risk factor for poor health, yet growing evidence suggests that where fat is stored may be as important as how much is present. MRI allows detailed assessment of fat accumulation across organs and tissues, revealing patterns that are not captured by body mass index alone. Using large-scale population data, researchers applied MRI-based fat measurements to identify distinct body fat distribution patterns and examine how these patterns relate to brain structure, cognitive performance and neurologic disease. The analysis highlights meaningful differences between individuals with similar overall body size but contrasting internal fat profiles, with implications for how neurologic risk is assessed in clinical and population settings.
Distinct Fat Distribution Profiles Identified by MRI
Analysis of MRI scans from a large UK cohort identified six reproducible body fat distribution profiles in both men and women after accounting for overall adiposity. These profiles were defined by how fat was distributed across organs such as the pancreas, liver, abdominal compartments and muscles rather than by absolute body weight.
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Two profiles were characterised by organ-predominant fat accumulation. One showed relatively high pancreatic fat, while another was marked by higher liver fat. A third profile, often described as “skinny fat”, combined moderate body size with comparatively high fat levels across several internal depots, including visceral and intramuscular fat. The remaining profiles reflected more even fat distribution, ranging from balanced high adiposity to balanced low adiposity, alongside a lean reference profile with consistently low fat levels across all measured regions.
These patterns demonstrate that individuals with similar body mass index values can have markedly different internal fat distributions, underscoring the limitations of global anthropometric measures for capturing metabolic and neurologic risk.
Brain Structure and Microstructural Differences Across Profiles
Clear differences in brain structure were observed across the fat distribution profiles. Compared with the lean reference group, most non-lean profiles were associated with lower total brain volume and reduced grey matter volume. These differences were evident in both sexes and affected cortical as well as subcortical regions, with more extensive involvement in profiles characterised by pancreatic-predominant fat and the skinny-fat pattern.
White matter changes also varied by profile. Higher levels of white matter hyperintensities were consistently seen in profiles with greater internal fat burden, indicating a higher lesion load compared with the lean profile. Microstructural analysis of white matter showed sex-specific patterns. In men, several profiles displayed widespread alterations suggestive of reduced neurite density and increased free water content, whereas in women these differences were more limited in extent.
Measures of brain ageing further differentiated the profiles. Men in several higher-adiposity profiles showed an older-appearing brain relative to chronologic age, while no clear differences in this measure were detected across profiles in women. Together, these findings point to a robust association between fat distribution patterns and both macrostructural and microstructural brain characteristics.
Cognitive Performance and Neurologic Disease Associations
Differences in cognitive performance aligned with the observed brain changes. Slower psychomotor speed was evident in several non-lean profiles in both men and women, particularly those with pancreatic-predominant fat, skinny-fat features or more uniformly high adiposity. Other cognitive domains showed more selective associations. Prospective memory performance was lower in specific profiles compared with the lean group, and visual memory differences were observed in the highest-risk profiles, with some variation between sexes.
Beyond cognition, fat distribution patterns were linked to differing risks of neurologic disease. Compared with the lean profile, higher internal fat burden was consistently associated with increased risk of mood disorders, including anxiety and depressive disorders, in both men and women. Certain profiles also showed elevated risks for other neurologic conditions, with the pattern of associations differing by sex. Notably, pancreatic-predominant and skinny-fat profiles were repeatedly implicated as higher-risk groups across multiple outcomes.
MRI-based assessment of body fat distribution revealed six distinct adiposity patterns that differ meaningfully in their associations with brain structure, cognition and neurologic disease. Profiles characterised by pancreatic-predominant fat accumulation and by relatively high internal fat despite moderate body size emerged as particularly unfavourable, showing more pronounced brain changes and poorer neurologic outcomes than the lean reference group. These findings emphasise that fat distribution, rather than body mass alone, is closely linked to neurologic health. Incorporating information on internal fat patterns may offer a more nuanced approach to identifying individuals at increased neurologic risk and refining prevention strategies beyond traditional measures.
Source: Radiology
Image Credit: iStock
