Waste-to-hip ratio affects the brain too

A new study by Loughborough University has found that people with waists larger than their hips have lower brain volume.

The Body Mass Index (BMI), waste-to-hip ratio and body fat of 9,652 people (average age of 55 years) was measured for the study. Among them, 19 per cent were found to be obese. BMI is the weight-to-height ratio—people with a BMI above 30.0 are considered obese. Waist-to-hip ratio is determined by dividing waist circumference by hip circumference.

Using a technique called magnetic resonance imaging, researchers studied the volumes of white and grey brain matter and volumes in various regions of the brain. Their findings revealed that those with higher ratios of obesity and waist-to-hip ratio had the lowest brain volume.

The study shows that “1,291 people who had a high BMI and a high waist-to-hip ratio had the lowest average grey matter brain volume of 786 cubic centimetres, compared to 3,025 people of healthy weight who had an average grey matter brain volume of 798 cubic centimetres and 514 people with a high BMI but without high waist-to-hip ratio who had an average grey matter brain volume of 793 cubic centimeters”.

They found no significant differences in brain volumes of white matter. “While our study found obesity, especially around the middle, was associated with lower grey matter brain volumes, it’s unclear if abnormalities in brain structure lead to obesity or if obesity leads to these changes in the brain,” says study author Professor Mark Hamer from the University’s School of Sport, Exercise and Health Sciences (SSEHS).

“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,” he adds.

Grey matter contains most of the nerve cells, and includes regions of the brain involved in muscle control, and sensory perception such as seeing, hearing, memory, speech, decision making, self-control etc.

“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,” says Prof Hamer.

The study was published in the journal Neurology.