Does obesity lead to lower IQ scores?
TUESDAY, MAY 19, 2015 10:19 AM

Researchers have been studying the negative effects of obesity for a long time. It's widely accepted that obesity leads to a higher risk for many health problems, including diabetes, heart disease and stroke. However, some studies have found that it may even correlate with psychological and neurological factors - including a person's IQ score. Read on for more about the relationship between body mass index and IQ:

The 'Homer Simpson' effect
One of the most commonly cited studies regarding IQ and its relationship to obesity was published in the journal Neurology in 2006. Researchers studied 2,223 men and women, and found that those with a higher BMI scored significantly lower on cognitive tests than those with a BMI in the healthy range. Not just that, though - after following up five years later, researchers found that higher BMIs were associated with declining cognition over time. The study's conclusion that being overweight may actually negatively affect intelligence has been referred to as the "Homer Simpson" effect, according to the Daily Mail. 

"The study's findings may be due to a host of factors including the thickening and hardening of cerebral vessels because of obesity or possibly the development of insulin resistance," Dr. Maxime Cournot, the study's lead author, told the Daily Mail.

The other scientific viewpoint
More recent studies may disagree with the first one's findings, though. In fact, myriad research has found that, while there isn't much evidence that having a higher BMI causes lower intelligence, the reverse is much more likely to be true. In other words, low IQ scores may lead to higher BMIs. A 2014 paper in the journal Endocrinolgy, Diabetes and Obesity analyzed several studies linking IQ and obesity, and discovered that people who scored lower on IQ tests were more likely to gain weight as adults, thus leading to obesity. Likewise, a 2013 study from the American Journal of Epidemiology found similar results in children. Researchers of the study found that lower IQ scores in children as young as 3 years old, were likely to result in obesity later in life.

Clearly, obesity and IQ are connected, and most researchers now agree weight gain may be the result of low intelligence and not the other way around. Health experts believe this is probably because people with lower intelligence are more likely to have poor nutritional and fitness habits than those with higher IQ scores.