Indications for Bariatric Surgery
Bariatric surgery is indicated for patients with BMI ≥40 kg/m² regardless of comorbidities, BMI ≥35 kg/m² with at least one obesity-related comorbidity, or BMI ≥30 kg/m² specifically for type 2 diabetes that could potentially achieve remission. 1, 2
Primary BMI-Based Eligibility Criteria
The threshold for bariatric surgery follows a tiered approach based on BMI and comorbidity burden:
BMI ≥40 kg/m²: Surgery is indicated regardless of the presence of comorbidities 1, 2
BMI ≥35 kg/m²: Surgery is indicated when accompanied by at least one obesity-related comorbidity including type 2 diabetes, hypertension, hyperlipidemia, obstructive sleep apnea, or non-alcoholic fatty liver disease 1, 2, 3
BMI ≥30 kg/m²: Surgery is specifically indicated for patients with type 2 diabetes when hyperglycemia remains inadequately controlled despite optimal medical treatment and the diabetes could potentially go into remission 1, 2, 3
Lower BMI thresholds for Asian populations: Adjusted criteria should be applied due to different body composition and metabolic risk profiles in this population 1, 2
Prerequisite Requirements Before Surgery
Patients must demonstrate failure of conventional weight loss approaches before surgical consideration:
Failed non-surgical interventions: Documented unsuccessful attempts at structured dietary interventions, physical activity programs, behavioral therapy, and pharmacotherapy 1, 2
Patient capability: Demonstrated motivation and ability to comply with long-term treatment protocols and lifelong follow-up requirements 1, 2
Acceptable operative risk: Medical evaluation confirming the patient can safely undergo surgery 2
Psychological stability: Understanding of required lifestyle changes and mental readiness for the procedure 2
Mandatory Pre-Surgical Evaluations
A comprehensive assessment battery is required before proceeding:
Medical evaluation: Complete assessment of all obesity-related comorbidities and overall health status 1, 2
Nutritional evaluation: Baseline nutritional status and identification of any deficiencies 1, 2
Mental health evaluation: Psychological assessment to ensure readiness and identify potential barriers to success 1, 2
For diabetic patients: Assessment of pancreatic insulin secretory reserve, tests to distinguish type 1 from type 2 diabetes, and evaluation using prediction scales for surgical outcomes 2
Expected Clinical Benefits
The evidence supports substantial improvements across multiple domains:
Weight loss: Significant and sustained BMI reduction, with meta-analyses showing reductions of 13.3-16.4 kg/m² depending on follow-up duration 4, 5
Metabolic improvements: Resolution or improvement of type 2 diabetes, hypertension, hyperlipidemia, and obstructive sleep apnea 1, 2, 3
Mortality benefit: Decreased overall mortality compared to non-surgical management 3, 6
Cancer risk reduction: Reduced risk of certain malignancies associated with obesity 1, 6
Post-Surgical Requirements
Long-term commitment is non-negotiable for success:
Multidisciplinary follow-up: Minimum 2 years of structured follow-up, often lifelong, with physicians experienced in obesity treatment and bariatric surgery 1, 2
Nutritional monitoring: Regular assessment and supplementation to prevent deficiencies 2
Psychological support: Ongoing mental health care to address behavioral and emotional challenges 2
Critical Caveats and Pitfalls
Not a standalone solution: Surgery requires comprehensive lifestyle changes; 20-30% of patients experience suboptimal response or weight regain despite surgery 2
Surgical complications: Perioperative mortality ranges from 0.03% to 0.2%, with risks of surgical complications and nutritional deficiencies 1, 3
Specialized centers required: Surgery must be performed by specialized surgeons in hospitals with dedicated multidisciplinary bariatric teams 1, 2
Special populations: For patients with decompensated cirrhosis, bariatric surgery should only be considered at the time of liver transplantation or thereafter; sleeve gastrectomy is preferred for well-compensated cirrhosis 1