Overweight people have smaller brains than the rest of us, scientists have found – and it could be a sign that excess weight causes brains to shrink.
Researchers from Loughborough University found that people with a high body mass index (BMI) and high waist-to-hip ratio had brains 12 cubic centimetres smaller.
The study looked at 9,652 people with an average age of 55, and used magnetic resonance imaging (MRI) to work out brain volumes.
Overweight people had lower levels of grey matter – which contains most of the brain’s nerve cells and includes brain regions involved in self-control, muscle control and sensory perception.
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Study author Dr Mark Hamer, PhD, of Loughborough University said, ‘Our research looked at a large group of people and found obesity, specifically around the middle, may be linked with brain shrinkage.
‘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.’
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.