Last updated Jan 24, 2019
Carrying extra body fat, especially around the middle, may be linked to brain shrinkage, according to a study published in the January 9, 2019, online issue of Neurology. For the study, researchers determined obesity by measuring body mass index (BMI) and waist-to-hip ratio in study participants and found those with higher ratios of both measures had the lowest brain volume.
BMI is a weight-to-height ratio. It is determined by dividing a person’s weight by the square of their height. People with a BMI above 30.0 are considered obese. Waist-to-hip ratio is determined by dividing waist circumference by hip circumference. People with bigger bellies compared to their hips have higher ratios. Men above 0.90 and women above 0.85 are considered to be centrally obese.
“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,” “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, PhD, of Loughborough University in Leicestershire, England
After adjusting for other factors that may affect brain volume, such as age, physical activity, smoking and high blood pressure, researchers found that while a high BMI alone was linked to slightly lower brain volumes, those with high BMI and waist-to-hip ratios had lower gray matter brain volumes than participants who did not have a high waist-to-hip ratio. They found no significant differences in white matter brain volume.
“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,” said Hamer. “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.”