Mindfulness is a common practice already widely used, that has shown benefits in terms of psychological and physical health. It is about learning or learn again to be self present and aware to the environment, across breathing, sensations, emotions and thought centering exercises, in the present moment without any judgement.

The goal is to evaluate the efficacy of "mindfulness" versus an active control group in bariatric surgery.

Inclusion Criteria:

• Adult patients: over 18 years
• Patients suffering from morbid obesity (BMI ≥ 40 kg/m²), or severe obesity (BMI ≥ 35 kg/m²) associate with at least a comorbidity likely to be improved by surgery
• Patient revised in second-line after the failure of a well conducted medical treatment, nutritional, dietetic and psychotherapeutic during 6 to 12 months : absence of enough weight loss or absence of maintain of weight loss
• Absence of any psychiatric counter-argument

Exclusion Criteria:

• Subjects responding to inclusion criteria of the French National Authority for Health
• Subjects without agoraphobia, or obsessive-compulsive disorder, in post-traumatic stress disorder, alcohol or drugs dependant, without psychotic disorders, major depressive disorder, or suffering from anti-social personality disorder
• Patient registered for social security
• Free, signed and informed consent