Men with a little extra body fat around the middle may also have slightly smaller brains, according to (a frankly hurtful) new study from the American Academy of Neurology. The findings, which take all the fun out of dad bod, suggest that men with more belly or visceral fat tend to also have less grey matter—which contains most of the brain’s nerve cells, as well as areas responsible for muscle control, hearing, memory, emotions, speech, decision making, and self-control.
“Our research looked at a large group of people and found obesity, specifically around the middle, may be linked with brain shrinkage,” study author Mark Hamer of Loughborough University in Leicestershire, England, said in a statement.
A large body of research (pun intended) indicates that belly fat is bad for your heart and can even increase your risk of cancer. One prior study of 733 people demonstrated that increased body fat was correlated with decreased brain size, but the results were somewhat inconclusive. Going into the study, Hamer and colleagues remained unsure how body fat might impact brain structure and function. “Existing research has linked brain shrinkage to memory decline and a higher risk of dementia,” Hamer said. “But research on whether extra body fat is protective or detrimental to brain size has been inconclusive.”
To learn more about the relationship between beer bellies and bird brains, Hamer and colleagues compared the Body Mass Index (BMI) and waist-to-hip ratio measurements of 9,652 men and women to how much white and grey brain matter they appeared to have in MRI brain scans. They found that the 1,291 people with the highest BMIs and waist-to-hip ratios also happened to have the lowest volume of grey matter (about three cubic centimeters less than those at healthy weight). Interestingly, fat did not seem to make a difference when it came to white matter, which helps facilitate communication between brain regions.
It’s important to note that researchers can’t say whether excess fat depletes grey brain matter directly, or whether people with less grey matter are more likely to overeat, or whether there’s a third, outside factor, that has not yet been considered. But even these preliminary findings could be a good motivator for men who recognize the need to deflate that spare tire.
“While our study found obesity, especially around the middle, was associated with lower gray matter brain volumes, it’s unclear if abnormalities in brain structure lead to obesity or if obesity leads to these changes in the brain,” Hamer said. “This will need further research but it may be possible that someday regularly measuring BMI and waist-to-hip ratio may help determine brain health.”