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,