LOSING weight comes with a host of health benefits - including making your brain sharper. Yes, it turns out that in addition to being bad for your heart, carrying excess weight may impair cognitive functions such as memory and attention. Losing weight, therefore, may help improve these mental functions, according to new research led by John Gunstad, assistant professor of psychology at Kent State University, and reported in the journal Surgery for Obesity and Related Diseases. A growing body of evidence suggests that obesity is linked to cognitive deficits, and it is a known risk factor for Alzheimers disease, dementia and stroke. So Gunstad and his team speculated that losing weight might improve mental function. For their study, they measured memory and attention in a group of 150 overweight participants, some of whom underwent gastric bypass surgery for weight loss and some who did not. All of the volunteers completed mental-skills tests to assess their baseline abilities of recall and attention at the beginning of the study, and again 12 weeks later, after some of them had the operation and lost weight. To begin with, about 24% of the patients showed impaired learning and 23% showed signs of poor memory recall when tested. By the end of the study, those who had lost weight (on average they shed about 17% of their initial body weight) had boosted their scores into the average or above average range for cognitive functions. Scores for the volunteers who didnt undergo weight-loss surgery dropped even further. We were cautiously optimistic going in that we would see a positive effect from the weight loss, but it was still great to see it, says Gunstad. Why would body weight have anything to do with brain function? It turns out that obesity works on a number of different metabolic pathways that can affect the way we process information. Obesity affects a number of physiological mechanisms that can have an adverse effect on the brain, says Gunstad. Hypertension, Type 2 diabetes, sleep apnea, all of which are consequences of being overweight, are all bad for the brain. Focusing on patients having weight-reduction surgery helped Gunstad to establish relatively quickly whether losing weight had any effect on mental function. TIME