Weight-loss surgery, known as bariatric surgery (from the Greek terms "baros" meaning "weight") represents a treatment strategies for dealing with obesity. The guidelines provide by the Consensus Conference of the National Institute of Health have established the following criteria of eligibility for surgical treatment:

INDICATIONS
- age between 18 - 60 (this limit is not absolute)
- BMI > 40 - BMI between 35 - 40 but accompanied by:

• pathologies associated with high-risk of death:
• hypertensio 
- diabetes - heart failure - osteoarthritis
• dyslipidaemia
• sleep apnoea syndrome
• need for weight loss in order to undergo orthopaedic surgery
• severe psychological discomfort caused by obesity limiting social life and social skills.

CONTRAINDICATIONS
ABSOLUTE:

• Obesity associated with endocrine diseases
• Major psychiatric disorders:
• Borderline personality disorder (BPD)
• Schizophrenia
• Severe active depression
• Uncontrolled eating disorders (binge eating)
• Drug and alcohol abuse
• Poor compliance of the patient to a long follow-up
• High-risk surgical patients
• Pregnancy

RELATIVE:

• cirrhosis of the liver
• organ transplant patients
• cancer patients
• CRI patients in dialysis