Stress can make you fat. Why? It’s biological. When your life is filled with stress and anxiety, your body produces high levels of the stress hormone cortisol, and British researchers have discovered there is a link between cortisol and excess weight. Cortisol is triggered when you experience the “flight-or-fight” response to danger. And while it’s helpful in short doses when real and sudden danger occurs, it is harmful when it is present in the body for long periods of time. The study found that those with higher cortisol levels tended to have larger waist circumferences, which was defined as more than 40 inches for men and more than 35 inches for women, as well as higher BMIs and body fat. In addition, higher levels of cortisol were linked to a higher risk of being obese for both men and women. Important caveat: Although the study found an association between cortisol and obesity, it did not prove a cause-and-effect link. But it is likely that a high level of stress leads some people to overeat as a way to compensate and that causes the excess weight gain.