Energy balance

Bariatric surgery's glycemic benefits in patients with BMI <35 kg/m2 are primarily driven by caloric restriction and weight loss rather than unique metabolic or hormonal mechanisms.

For patients with BMI <35, surgery is not a 'metabolic cure' distinct from weight loss. The glycemic benefits are largely due to the caloric restriction and weight loss achieved. While surgery is more effective at producing and sustaining this weight loss than lifestyle changes alone, the underlying mechanism is energy balance, not a unique surgical hormone effect. Patients should understand that achieving similar weight loss through other means could yield similar metabolic improvements, though sustaining that loss is the primary challenge.