The main objective of this study is to compare the efficacy of two weight losing strategies (obesity surgery with gastric banding, and standard of care) on physical performance in elderly obese persons submitted to a physical training. Our hypothesis is that a surgery-induced weight loss in the context of a physical training (which is recommended in people 60-75 yrs losing weight) improves physical performance as compared to standard of care (3-5% weight loss).

Randomized clinical trial; Single Blind A physical training is recommended in people above 60 yrs. engaged in a weight-losing program, in order to prevent the impairment of physical performance. Therefore a physical training program (endurance and strength training) will be implemented for all subjects participating in the study, starting 1 month before randomization. It will last for 13 months. Patients will be randomized either in the surgical group (gastric banding under general anesthesia) or in the reference group (mild calorie restriction and coaching). Physical performance of patients is evaluated at screening, inclusion, at randomization, 6 and 12 months after randomization.

Inclusion Criteria:

Criteria specific to the study Subjects aged 60 or over and younger than 75 yrs., seeking obesity treatments, seeking obesity surgery, with a BMI of 30 kg/m² or more, with comorbidities (see below), and a mildly decreased physical performance (SPPB between 5 and 8) are considered to participate in the study Criteria specific to obesity surgery This projects extends the classical recommendation for obesity surgery to people with a BMI of 30 and over with either the comorbidities list below, or a SPPB between 5 and 8. This level of physical impairment can be considered as a comorbidity in the elderly.

The French Ministry of health (HAS) recommends that obesity surgery be considered (here with a gastric banding) in patients fulfilling the following criteria:

• Subjects with a BMI of 40kg/m² or more, or 35kg/m² or more if at least one comorbidity that can be improved by weight loss is present among hypertension, obstructive sleep apnea, severe metabolic disorder (such as type 2 diabetes, NASH), or rheumatologic conditions associated with disability.
• After the failure of well designed medical, dietetic, psychological intervention followed up for 6-12 months, with no sufficient weight loss or in case of the failure of maintaining weight loss
• In subjects well informed of the consequences of surgery, and after a multi-disciplinary evaluation
• Subjects have understood and accepted the need for a long term medical and surgical follow up
• The risk of surgery is acceptable
• patient who signed the informed consent
• patient affiliated to a social security cover or equivalent

Exclusion Criteria:

Criteria specific to the study

• These are the impossibility to follow a physical training (unstable coronary heart disease, severe lung function impairment, rheumatologic conditions preventing training, a SPPB score below 5, cancer treatment within the 3 last months, Parkinson's disease, other severe illness that may interfere with physical activity) Criteria specific to gastric banding
• Cognitive impairment (MMSE ≤ 25)
• Severe eating disorder
• Impossible long-term follow-up
• Alcohol or drug dependence
• Lack of previous well designed obesity care
• Vital prognosis engaged in the short term
• Contra-indications to anaesthesia Classical criteria for the non inclusion in a trial
• The subject is in jail, or has freedom restriction
• Guardianship curators or judicial protection
• Patients participating in another intervention study.