Are Fat People Stupid?

At work recently I was asked to describe the links between obesity and (impaired) cognitive function. Before researching it, I wasn’t aware that there were any links, but surprisingly there is a fairly large amount of research on overweight people and their IQ. What is not clear, however, is if people with ‘poorer integrative mental processes’ have this affliction because they are overweight, or they are overweight because of their impaired mental function.

There are a number of ways of looking at this, and every viewpoint seemingly provides us with a different answer. There is a wealth of information suggesting that people who get more sleep are more likely to be (what society considers) intelligent. Obesity can lead to a narrowing of the windpipe and resultant obstructive sleep apnea, which leads to poor quality sleep. That’s a link in itself, and suggests that obesity is the cause, rather than the effect. Diabetes is an oft-cited side-effect of obesity, and again there are somewhat tenuous associations made between diabetics and low-IQ. Glycemic control in diabetics seems to be the most important factor in determining cognitive function, but it’s highly dependent on the type and severity of the illness.

Other people suggest that it is good cognitive abilities that may protect from obesity. If the brain is working well, then it’s more likely to tell the body that it’s no longer hungry in good time. People with good cognitive abilities may also have worked their way into a competitive environment, in which there are additional pressures placed on our body image. Another link I found was that being breast-fed for a longer period of time makes you cleverer and less likely to get fat. If that didn’t confuse the matter enough, obese children are more likely to get bullied and miss school, either compounding or creating the problem.

Conversely, there’s (yet more) scientific evidence that a heavy intellectual workload can lead to over-eating and obesity. Children with high-functioning autism and above-average IQ are also more likely to be obese than their non-autistic counterparts.

The conclusion is, essentially, that no-one has a fucking clue.

Image via Wikipedia

A final note to make on the topic is that people from lower socio-economic backgrounds are more likely to be obese, and people from these backgrounds often fare worse in academic tests, and may not have access to the best education. After adjusting for the level of education the participants receive, the link between obesity and intelligence ain’t so strong. So maybe it’s our definition of intelligence that’s the problem.

Read the original article here. All other information can be found (and probably counteracted) with a quick search on Google Scholar.