Researchers at Loughborough University in England have revealed that carrying excess weight around your midsection may affect your brain health, even leading to a concerning decline in brain volume. Brain shrinkage, in turn, increases your risk of memory loss and other cognitive problems.
The study involved more than 9,600 participants with an average age of 55, who received scores for both body mass index (BMI), a flawed formula that divides your weight by the square of your height, and waist-to-hip ratio (WHR). Your waist-to-hip ratio is a more reliable indicator of your future disease risk than BMI because a higher ratio suggests you have more visceral fat — a measure BMI tells you nothing about.
The participants also received structural MRI, which provided brain images, allowing researchers to measure the volume of gray and white matter in the brain. After accounting for other risk factors, such as smoking and exercise levels, the researchers found a slight link between BMI and lower gray matter volume.
However, a much more significant connection was found for people with both high BMI and WHR. “The combination of overall obesity and central obesity was associated with the lowest gray matter compared with that in lean adults,” the researchers noted.
Specifically, participants with a BMI and WHR in a healthy range had an average gray matter brain volume of 798 cubic centimeters. This dropped to 786 cubic centimeters among those with a high BMI and high WHR.
For the study, people with a BMI above 30 were considered obese while central obesity was determined by a waist-to-hip ratio above .90 for men and .85 for women. Study author Mark Hamer, Ph.D., said in a press release:5
“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.
We also found links between obesity and shrinkage in specific regions of the brain. 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.”