Study Finds Dramatic Weight Loss Improves Memory, Concentration

The news story that is the basis of this blog entry reports that scientists “discovered” if they give people money making weight loss surgery their memory will improve. This story belongs in the Scientists R Stoopid section because the scientists have no idea why weight loss surgery improves memory.

The original news story is reprinted next.


Patients who lose a significant amount of weight get more than general health benefits, they get improved mental health as well – particularly when it comes to memory and concentration.

News about obesity problems, particularly among children, are frequent occurrences in today’s America. Generally speaking, however, the focus when it comes to weight loss is on general health – as well as long-term problems for which obesity is a significant risk factor (e.g. diabetes, heart disease, etc.). No one is suggesting that focus should change, but a new study out of Kent State University has shown there’s more weight loss than improving physical health – it improves patients’ mental health as well, particularly memory function and concentration.

Conducted by John Gunstad, an associate professor of psychology, and a team of researchers spanning several locations, the study group examined 150 people. Average group weight was 300 pounds, and all were considered clinically obese for their body size, as well as having other health problems such as hypertension, diabetes (type 2) and sleep apnea. Unlike other studies, where a control group is usually half of the participants, health concerns limited the control group to less than a third (41 patients). The remainder of the participants had surgery to assist their weight loss, typically gastric bypass (though some other methods were used). The participants who had surgery lost an average of 50 pounds over 12 weeks – quite significant weight loss – and rejoined the other still-obese participants at that time.

Before the surgery, all of the participants had undergone a battery of cognitive tests designed to test memory, concentration, and organizational skills. In repeating the same style of tests after 12 weeks, all of the surgery patients saw statistically significant improvement on the tests. Those who had not lost weight not only showed no improvement but – somewhat alarmingly – showed a mild decline in memory function.

Given the sample size, conclusions of the study have to be tempered, but the near-universal improvement – and sharp divide between the two groups – shows promise for the role of weight loss in improving mental health. According to Gunstad, “We’ve known for a while that diet and exercise may also improve cognition.” Moreover, weight loss has an impact independent of other factors such as high blood pressure, because few of those who lost weight were no longer considered to have hypertension. The health of the brain is tied to a more holistic picture of physical health, he suggested.

HULIQ sees at least two outstanding questions not resolved by the study. One, which was noted by the researchers on the project, is whether less dramatic weight loss can also have an impact on cognitive ability. Second, noting that many of the patients had sleep apnea, but were likely able to sleep more comfortably after weight loss, finding a way to control for sleep habits would be a necessary element of future studies. Getting a good night’s sleep has long been tied to proper memory and cognitive function. That said, since Gunstad stressed the holistic improvement bestowed by weight loss, and the role of a generally healthy lifestyle (rather than artificial, sudden weight loss) the comfort derived from weight loss does not necessarily blunt the study’s conclusions.

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