Feb. 3, 2006 - The stress hormone cortisol isn't the bad boy behind obesity, a new study suggests.
Several popular supplements claim to aid weight loss by helping you fight cortisol. But even if they did reduce cortisol levels, which is far from proven, they won't help you lose much weight, says Malcolm Low, MD, PhD.
Low is senior scientist and associate director of the Center for the Study of Weight Regulation and Associated Disorders at Oregon Health & Science University in Portland. His research delves into the complex web of hormones and other chemical signals that affect weight loss and weight gain.
Cortisol is the most abundant of the steroid hormones called glucocorticoids. But even if one takes all of these hormones together, they still don't add up to a single answer to the complex problem of obesity.
"There are multiple controls in our body that regulate body weight and appetite," Low tells WebMD. "Glucocorticoids are clearly involved in control of body weight. But it is not the only hormone involved. There are multiple systems involved in the brain and outside the brain that regulate how much fat we are going to have and how much appetite. There is no simple answer to treating obesity."
People looking for simple answers to their weight problems are going to be disappointed, says Marci Gluck, PhD, of the New York Obesity Research Center at St. Luke's-Roosevelt Hospital and Columbia University.
"Consumers see these cortisol-reduction medications advertised for weight loss, but they probably are not going to be effective," Gluck tells WebMD.
Stress = Weight Gain? Not So Simple
The body makes cortisol to help us handle stress. When stress goes up, cortisol levels go up. And it's often repeated that obese people have higher cortisol levels than lean people. But that is a myth, says cortisol expert Barnett Zumoff, MD, professor of medicine at Albert Einstein College of Medicine in New York.
"Cortisol production is not increased in obesity. And cortisol blood levels are not increased in obesity," Zumoff tells WebMD. "Obesity has nothing to do with cortisol."
Zumoff says that while he has written about this for 20 years, there's still a common misperception that cortisol underlies weight gain. Low agrees.
"The message has gotten across that glucocorticoids are involved in all obesity. And there is a lot of common talk about the role of stress in increasing glucocorticoids," Low says. "It seems to make sense: There is a lot of stress today, and obesity is up. But when you look at the facts, it is not as clear."
Gluck studies the relationship between cortisol, stress, and weight gain. It's a very complicated story.
"Most scientists agree that it is not a simple one-to-one relationship between cortisol and weight gain," she says. "There are so many different peptides and hormones involved. Cortisol might not be the primary one."
Low's work makes it clear that there are several systems that regulate how much energy we take in, how much energy we burn, and how much energy we store as fat. Each of these systems interacts. And each system backs the others up, so that when one falters, another revs up.
"For the average person who has gained a bit too much weight, the problem isn't that he or she makes too much cortisol," Low says. "It is probably that this person eats too much fast food and doesn't exercise. Even if such people have elevated cortisol, it is because they have excess fat, not because there was too much cortisol to begin with. The medical condition of excess cortisol is unusual."