Cortisol is a hormone that is produced in reaction to stress. It is also produced more when people are depressed and plays a role in regulating people's metabolisms. There is thought to be a link between depression, cortisol and obesity but no-one is quite sure how this works. A team of researchers from Penn State University in the U.S. looked into this issue in a sample of 111 boys and girls between 8 and 13. The children were assessed for their levels of depression, weighed and measured and had their cortisol levels taken before and after an assessed maths test designed to raise their stress levels. The children who were more depressed showed a higher increase in their levels of cortisol after being stressed but this was only associated with obesity in the case of the girls.
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