Study: Does Obesity Shrink Our Brains?

An increased percentage of fat in the body is associated with a smaller brain

How does it affect our brains when we are overweight or obese? Researchers have now found that people with a higher BMI and larger fat deposits around the central part of the body have smaller brains compared to people of normal weight. The decrease in brain size increases linearly the more fat there is around the middle of the body.

In their current study, scientists from Loughborough University in England found that an increased amount of fat around the middle part of the body is associated with a reduced brain volume. The doctors published the results of their study in the English-language journal "Neurology".

What is the gray matter in our brain?

If you are overweight or obese and have a lot of fat around the middle of your body, this could result in a reduction in the volume of gray matter in your brain. The so-called gray matter contains the majority of the 100 billion nerve cells in the brain, while the white matter is filled with nerve fibers that connect the brain regions. Previous studies have already found links between atrophy of the gray matter and the risk of dementia, explains study author Mark Hamer, professor at Loughborough University.

Every fifth participant in the study was obese

The study measured body mass index (BMI) and the ratio of waist to hip in 9,652 middle-aged subjects. A BMI between 18.5 and 24.9 is considered healthy, while a BMI over 30 is considered obese. The study also evaluated the waist to hip ratio, a high score of over 0.90 in men and over 0.85 in women means that a person has a high abdominal fat percentage or a larger belly than the hips. Based on these criteria, it was determined that almost one in five participants in the study was obese.

The brain volume of the test subjects was also examined with the help of magnetic resonance imaging (MRI). When evaluating the data, factors such as age, physical activity, smoking and high blood pressure were taken into account, which can lead to a reduction in brain volume. The results of the study showed that people with higher BMI and waist to hip ratios had the lowest volume of gray matter. The decrease in brain size increases linearly, the greater the fat content in the middle part of the body, says Professor Hamer.

What could the doctors find out?

1,291 subjects with a BMI of 30 or higher and a high waist to hip ratio had the lowest average volume of gray matter at 786 cubic centimeters. 514 people with a BMI of 30 or higher, but without central obesity, had an average volume of gray matter of 793 cubic centimeters. 3,025 participants with healthy values ​​had an average volume of gray matter of 798 cubic centimeters. There were no significant differences in white matter brain volume associated with obesity. However, excessive weight was associated with gray matter shrinkage in four regions of the brain. It is unclear whether abnormalities in the brain structure lead to obesity or whether obesity leads to these changes in the brain, explains Professor Hamer.

More research is needed

People with obesity and people with a larger waist-to-hip ratio (a marker for visceral fat around the abdomen) had a lower volume of gray matter. This relationship between reduced brain volume and abdominal fat could indicate that inflammation and vascular factors play a role. Future research should examine inflammation, nutrition, and vascular health to better understand possible connections between brain health and obesity. Obesity can adversely affect a variety of health parameters. People should therefore strive to maintain a normal body weight, summarizes Professor Hamer. (as)

Author and source information

Video: Obesity: Its More Complex than You Think. Fatima Cody Stanford. Radcliffe Institute (January 2022).