Several have pointed out that most studies (including this one) can usually only find correlation. It is extremely difficult and expensive to find the direction of causality in any correlation (not to mention teasing out intermediating effects and confounders)... But it seems very likely to me (sidestepping the otherwise worthwhile debate on BMI being a good measure of obesity) that rather than obesity causing low intelligence, the direction of causality might be the other way around: Low intelligence persons gradually getting fat.
My thinking on this stems from an anthropological concept known as the 'thrifty gene hypothesis'. Its an idea which essentially states that: in times of projected shortages in food, genes which store as much energy as possible might be advantageous as a survival mechanism and thus may be selected for. Thus if a person who is genetically stupid, and knows it (subconsciously or not), and projects that there is less hope of getting a good stable job as a means for sustenance and survival, he/she will be more likely to activate the thrifty gene to store up energy to compensate for a projected lack of occupational marketability.
Slashdot Mirror
Several have pointed out that most studies (including this one) can usually only find correlation. It is extremely difficult and expensive to find the direction of causality in any correlation (not to mention teasing out intermediating effects and confounders)... But it seems very likely to me (sidestepping the otherwise worthwhile debate on BMI being a good measure of obesity) that rather than obesity causing low intelligence, the direction of causality might be the other way around: Low intelligence persons gradually getting fat.
My thinking on this stems from an anthropological concept known as the 'thrifty gene hypothesis'. Its an idea which essentially states that: in times of projected shortages in food, genes which store as much energy as possible might be advantageous as a survival mechanism and thus may be selected for. Thus if a person who is genetically stupid, and knows it (subconsciously or not), and projects that there is less hope of getting a good stable job as a means for sustenance and survival, he/she will be more likely to activate the thrifty gene to store up energy to compensate for a projected lack of occupational marketability.