Being overweight or obese has long been linked to poor heart health, but could it also impair your thinking?
New research out of Canada suggests it very well might.
Working with thousands of young, middle-aged and older adults, the new study highlights what appears to be fat’s direct harm on one’s ability to think quickly, with rising body fat levels linked to diminishing mental health returns.
The study identified a fat-induced slow-down in “processing speed” — meaning the time it takes to absorb, understand and react to sights, sounds or movement.
Between 2010 and 2018, nearly 9,200 adults aged 30 to 75 years (average age: 58) were enrolled in the study. None had a prior history of heart disease.
All underwent brain scans (MRIs) to pinpoint potential blood vessel injuries. Almost all had total body fat measurements, while about three-quarters completed assessments of belly fat as well.
To gauge their thinking, the participants completed two tests that examined attention skills, concentration, short-term memory, eye-hand speed and coordination, and the ability to learn and/or calculate new information.
On the physical health front, there were few surprises.
Women carried more overall body fat than the men, though guys tended to pack on more excess weight around their stomachs. About two-thirds of the men had what the authors characterized as “central obesity,” compared with just over one-third of the women.
Still, carrying excess weight — regardless of where — was found to pose a threat to heart health, with higher overall body fat and abdominal fat driving up both high blood pressure and diabetes risk.
Excess body fat also appeared to boost the risk for brain injury, including lesions or the kind of markers that indicate a history of unrecognized (“silent”) strokes.
And Anand and her colleagues noted that poorer heart health has long been known to put a person’s ability to think clearly and quickly at risk.
But this study went one step further, identifying what appears to be excess fat’s direct damage to thinking, even after taking into account heart health, brain status and education.
In fact, the researchers identified a direct more-is-more dynamic: As body fat rose, people processed information more slowly, as if their brains had actually aged.
Specifically, the team noted that a participant’s ability to think “aged” up by about one year for every 9% increase in overall body fat.
Yet not every aspect of thinking skill appeared to be affected.
Processing speed and attention skills declined with rising fat levels. “The greater the percent of body fat, the greater the loss of processing speed,” the study noted.
However, verbal understanding and memory skills did not appear to be similarly affected.
Anand said it remains unclear whether a fat-induced loss of processing speed is permanent or if slimming down might reverse the situation. Either way, avoidance is key. Try to keep active and eat a healthy diet to prevent pounds from piling on to begin with.