The type of obesity most dangerous for the brain has been named

Not only the amount of fat in the body, but also where it accumulates affects brain health and cognitive abilities. This is the conclusion reached by scientists who analyzed data from more than 18,000 adult participants in the UK Biobank.

The study was published in the journal Nature Mental Health (NMH).

Body mass index (BMI) is typically used to assess obesity, but this measure does not reflect the distribution of adipose tissue. Meanwhile, fat in different parts of the body can affect health in different ways. A team of scientists led by Anqi Qiu from Hong Kong Polytechnic University set out to determine how fat deposits in various areas of the body are associated with brain structure and function.

The study included more than 18,000 individuals with an average age of approximately 62 years. Using dual-energy X-ray absorptiometry, the scientists measured the amount of fat in the arms, legs, trunk, and around the internal organs of the abdominal cavity — known as visceral fat. Participants then underwent several types of magnetic resonance imaging of the brain and a series of cognitive tests assessing memory, processing speed, reasoning ability, and executive functions.

The analysis showed that different types of fat deposits are associated with different brain changes. Visceral fat proved to be the most detrimental. It showed the strongest correlation with deterioration of the brain's white matter — the network of nerve fibers that transmit signals between different parts of the nervous system. In people with large amounts of visceral fat, the scientists found signs of decreased nerve fiber density, fluid accumulation in brain tissues, and disruption of their organization.

The researchers also calculated the so-called "brain age" — a measure reflecting the degree of neural network aging. It turned out that accelerated brain aging serves as the primary mechanism through which excess fat impairs cognitive abilities. Across all tests conducted, visceral fat once again demonstrated the most pronounced negative impact on thinking and memory.

The scientists believe that the findings demonstrate that assessing the risks of age-related cognitive decline requires considering not only a person's overall weight but also where exactly in the body adipose tissue accumulates.