You've seen ads for weight-loss products that include some derivative of the word cortisol. While I do not endorse these products, the hormone cortisol plays a critical part in how the body deals with stress.
Cortisol itself, produced in the adrenal cortex, does not pose a threat to the body; its purpose is to help our bodies deal with stress and maintain a healthy immune system.
But prolonged stress can induce an overproduction of cortisol, leading to an increase in blood pressure, blood sugar levels and abdominal fat while suppressing the body's ability to fight cold and infection.