There is no solid evidence that cortisol blockers lead to weight loss.
Manufacturers of cortisol blockers claim that high stress levels increase your body's production of the hormone cortisol, which increases appetite and leads to weight gain.
However, the connection between stress hormones and weight gain is largely based on anecdotal evidence, with only a few studies supporting it. The role of hormones on weight gain remains unclear.
As for evidence that cortisol blockers cause weight loss, the Federal Trade Commission charged the marketers of some cortisol blockers with making false and unsubstantiated claims about their products' effectiveness. As a result, the companies had to pay millions of dollars in refunds and stop making unproven claims about their products.
Bottom line: Steer clear of weight-loss products that make unproven claims. Instead, focus on reducing your calorie intake and increasing your activity level. For lowering stress, explore stress management techniques.