There is no definitive evidence showing that cortisol blockers are effective as weight-loss tools as of 2015, according to Mayo Clinic. However, manufacturers of cortisol blockers claim that they aid in weight loss by blocking the production of cortisol, a hormone in the body. These claims are not substantiated.
According to manufacturers of cortisol blockers, cortisol in the body causes an increase in appetite that leads to eating more and gaining weight. Blocking the production of cortisol purportedly causes reduced appetite. Still, the Federal Trade Commission has charged some marketers of cortisol blockers with making unsubstantiated or false claims, resulting in millions of dollars in refunds to customers, notes Mayo Clinic.