Research and Evidence

Researchers found Hypnosis and guided visualization were over 30 times as effective for weight loss than dieting alone. 

Researchers compared 18 weight loss studies comparing normal diet programs using relaxation training, self-monitoring, goal setting, and cognitive behavioral therapy to programs which included Hypnotherapy. Those who received hypnosis lost more weight than 90% of non-hypnosis participants. Additionally, the Hypnosis group maintained the weight loss two years after treatment ended.

Cochrane, Gordon; Friesen, J. (1986). Hypnotherapy in weight loss treatment. Journal of Consulting and Clinical Psychology, 54, 489-492

1. In a trial investigating the effects of hypnosis in weight loss for 60 females, at least 20% overweight. Treatment included group hypnosis with metaphors for ego-strengthening, decision making and motivation, ideomotor exploration in individual hypnosis, and group hypnosis with maintenance suggestions. Hypnosis was more effective than a control group: an average of 17 lbs lost by the hypnosis group vs. an average of 0.5 lbs lost by the control group, on follow-up.
Cochrane, Gordon; Friesen, J. (1986). Hypnotherapy in weight loss treatment. Journal of Consulting and Clinical Psychology, 54, 489-492. 

2. Study of the effect of adding hypnosis to cognitive-behavioral treatments for weight reduction, additional data were obtained from authors of two studies. Analyses indicated that the benefits of hypnosis increased substantially over time.
Kirsch, Irving (1996). Hypnotic enhancement of cognitive-behavioral weight loss treatments--Another meta-reanalysis. Journal of Consulting and Clinical Psychology, 64 (3), 517-519. 

3. An analysis of five weight loss studies reported in the Journal of Consulting and Clinical Psychology in 1996 showed that the "weight loss reported in the five studies indicates that hypnosis can more than double the effects" of traditional weight loss approaches.
University of Connecticut, Journal of Consulting and Clinical Psychology in 1996 (Vol. 64, No. 3, pgs 517-519).

Two Years Later: Hypnosis Subjects Continued To Lose Significant Weight

109 people completed a behavioural treatment for weight management, either with or without the addition of hypnosis. At the end of the 9-week program, both interventions resulted in significant weight reduction.

However, at the 8-month and 2-year follow-ups, the hypnosis subjects were found to have continued to lose significant weight, while those who didn't use hypnosis in addition to the behavioural-treatment-only showed little further change.

Journal of Consulting and Clinical Psychology (1985)