Researchers from Washington University in St. Louis have discovered that overweight children are less intelligent than their slimmer peers. In addition, the former have an increased risk of developing depression. The results of the study are published in the journal JAMA Pediatrics. Scientists analyzed the mental abilities of more than 2,500 girls and 2,700 boys aged nine to 11 years with the help of special intellectual tests. The study assessed the subjects' vocabulary and the logic of their thinking. Two years after the study began, the scientists found that the children who performed worse on the tasks had a higher body mass index by an average of 0.012 (1.6%). It also became clear that overweight children were more likely to show symptoms of depression. The researchers explained that an unhealthy diet, combined with a sedentary lifestyle, causes developmental problems in children, including undesirable changes in prefrontal cortex functioning and working memory deficits.