It is well known that obesity can lead to complications such as type 2 diabetes mellitus and other diseases. Researchers have now discovered that an increased body fat percentage can also affect cognitive performance – and in a negative way.
Those who are overweight have a higher risk of metabolic diseases, arthrosis and diseases of the cardiovascular system and internal organs such as the kidneys, liver and gallbladder.1 But apparently being overweight can also have a negative effect on the ability to think. That’s according to a new study from Canada.
Connection between obesity and the ability to think
A team of researchers studied 9,189 adults between the ages of 30 and 75 (mean age 58). None of them had any previous cardiovascular disease. 9,166 of them underwent bioelectrical impedance analysis, a procedure that determines a person’s body fat percentage. The scientists also performed an MRI on 6773 to check for possible vascular brain injuries, i.e. damage to the blood vessels in the brain. They also used this method to measure the volume of visceral adipose tissue, i.e. abdominal fat.2
The participants then completed two tests. Factors such as attention span, concentration, short-term memory, eye-hand coordination and the ability to learn and use new information were tested.
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Increasing body fat percentage causes the brain to “age”
The result of the study: With increasing body fat percentage, the tested people processed information more slowly. Their brains appeared to have «aged» compared to the non-obese participants. Put in numbers, for every 9 percent increase in total body fat, the brain ages by about a year. Being overweight has a negative effect on the ability to think.
Processing speed and attention are particularly affected. These areas decreased with increasing fat content. On the other hand, memory and verbal comprehension were not affected.
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Increased risk of brain injury
But the research team not only recognized a connection between the amount and distribution of adipose tissue and cognitive abilities. As the study found, excess body fat also appears to increase the risk of brain injury. This became clear during the MRI scans, which also made it possible to visualize undetected strokes and lesions in the brain.
In addition, the authors of the study once again emphasized that being overweight – regardless of whether it is total body or abdominal fat – significantly increases the risk of cardiovascular disease. These include high blood pressure and the risk of developing diabetes.
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Conclusion
«Our results are intriguing because we show that increased fat levels not only increase typical cardiovascular risk factors, such as diabetes and hypertension, but also affect cognitive outcomes,» said lead author of the study, Dr. Sonja Anand, director of the Population Health Research Institute at McMaster University in Hamilton, Ontario (Canada).3
But the study also has limitations. It remains unclear whether a loss in processing speed caused by adipose tissue is permanent or whether weight loss could reverse the condition.