The effectiveness of hypnosis as an intervention for obesity: A meta-analytic review.

Two meta-analyses were performed quantifying the effectiveness of hypnosis as an intervention for obesity and the impact of adding hypnosis to cognitive–behavioral therapy (CBT) in producing weight loss. The primary meta-analysis comparing hypnosis with a control condition produced large effect sizes of 1.58 (p ⩽ .001) for 14 trials at the end of active treatment and 0.88 (p ⩽ .001) for 6 trials at the longest follow-up. The average participant receiving some form of hypnosis lost more weight than about 94% of control participants at the end of treatment and about 81% of controls at follow-up. The secondary meta-analysis comparing CBT with the same intervention augmented by hypnosis generated a small effect size of 0.25 (p ⩽ .05) for 11 trials at the end of active treatment and a large effect size of 0.80 (p ⩽ .001) for 12 trials at the longest follow-up in favor of the blended intervention. The average participant receiving CBT plus hypnosis lost more weight than about 60% of participants receiving only CBT at the end of treatment and about 79% of participants receiving only CBT at follow-up. Our findings suggest hypnosis is very effective in producing weight loss over a relatively short span of time, but more research is needed on the long-term benefits in follow-up periods of 1 to 5 years. Clinicians should view hypnosis as a promising treatment option for obesity, especially when used in conjunction with CBT techniques for weight loss.