Bariatric surgery
Bariatric surgery is the most effective durable treatment for severe obesity, offered to patients with BMI 40 or greater, or BMI 35 or greater with an obesity-related comorbidity, after medically supervised weight-loss attempts have failed. Sleeve gastrectomy and Roux-en-Y gastric bypass are the dominant procedures, and outcomes hinge on catching early anastomotic or staple-line leak (tachycardia is the key sign) and on lifelong nutritional surveillance for iron, B12, folate, calcium, vitamin D, and thiamine deficiency.
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What this article covers
- Overview
Definition: bariatric surgery treats severe obesity by restricting caloric intake, inducing malabsorption, or both, producing durable weight loss and comorbidity remission that lifestyle and pharmacotherapy rarely achieve alone.
- Epidemiology
Rising demand: sleeve gastrectomy is now the most frequently performed bariatric procedure in the United States.
- Risk factors
Male sex, age over 60, and BMI greater than 60: the strongest predictors of perioperative morbidity and mortality.
- Pathophysiology
Sleeve gastrectomy is restrictive: the greater curvature is excised, an approximately 85% reduction in gastric volume that limits intake; the smaller surface also lowers ghrelin and augments GLP-1 satiety signaling.
- Clinical features
BMI 40 kg/m² or greater without a required comorbidity: meets criteria for surgery on obesity alone (class III obesity).
- Differential diagnosis
Secondary endocrine obesity (Cushing syndrome, hypothyroidism, polycystic ovary syndrome): an identifiable driver should be treated before surgery.
- Diagnosis
Establish eligibility by the BMI-and-comorbidity criteria: BMI 40 kg/m² or greater alone, or BMI 35 to 39.9 kg/m² plus a qualifying comorbidity, plus documented failed medically supervised…
- Management
Optimize comorbidities and counsel before surgery: treat sleep apnea, hypertension, and hyperglycemia, stop smoking, and confirm the patient accepts lifelong dietary change and follow-up.
- Complications
Pulmonary embolism: the leading cause of perioperative death across all bariatric procedures.
- Prognosis
Weight loss is durable: up to 70% of excess weight is lost with RYGB and 60% with sleeve gastrectomy at 2 years, sustained at 5 years, with BPD-DS producing the greatest loss.
- Prevention
Screen every candidate before surgery: confirm BMI against the 40, or 35-with-comorbidity, threshold and complete nutritionist and health-psychology evaluation.
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