In the film "Animal House" Dean Wormer told Kent "Flounder" Dorfman, "fat, drunk and stupid is no way to go through life, son-" When shown photos of lean and obese people, people consistently rated overweight individuals as dull-witted and less intelligent. It turns out there may
be some truth to these prejudices. French researchers found that overweight, middle-aged adults tested poorly on memory, attention and learning abilities compared to lean people.
Obesity is a sign of poor metabolic health and is a significant risk factor for some diseases (e.g., Alzheimer's disease). They studied 10, memory attention and speed of learning of nearly 2,500 middle-aged men and women in 1996 and 2001. Overweight people scored lower on the tests in 1996 and test scores declined even more in 2001.
The researchers speculated that poor metabolic health (insulin resistance and diabetes) contributed to deterioration of the nervous system in overweight adults.