Carrying extra body fat, especially around the stomach or tummy area could lead to shrunken brains.
A new study published in the Neurology Journal found that affected individuals had lower brain volumes especially in a part of the brain known as Grey matter
Most nerve cells in the brain are contained in the Grey matter. It is also the part of the brain that is associated with intelligence, self-control, muscle regulation and sensory perception.
High levels of brain shrinkage, especially when the reduction is happening at a fast rate, has been linked to reduced levels of intelligence, memory problems as well as mental health challenges like depression and dementia.
The adverse effects of reduced brain sizes are mostly prominent in older people, such as those in their late 60s or 70s since the shrinkage process is usually rapid among senior citizens.
However, health experts are concerned that lifestyle factors such as obesity and inactivity are predisposing young people to the problem.
"Existing research has linked brain shrinkage to memory decline and a higher risk of dementia, but research on whether extra body fat is protective or detrimental to brain size has been inconclusive," said Dr Mark Hamer, the lead author of the study from Loughborough University in Leicestershire, England.
The study looked at 9,652 people with an average age of 55. Of that group, 19 percent were found to be obese.
The researchers determined the obesity status of the study participants by measuring their body mass index (BMI) and waist-to-hip ratio.
Results showed that those with higher ratios of both measures had the lowest brain volume.
The BMI is a weight-to-height ratio test. People with bigger bellies compared to their hips are considered to have higher ratios. Men and women with a score of 0.90 and 0.85 respectively are deemed obese.
A 2016 study conducted by the Boston University School of Medicine and published in the Neurology Journal found that people who were in poor physical fitness during their 40s had significantly lower brain volumes by the time they reached age 60.