Predictors of weight loss and reversal of comorbidities in malabsorptive bariatric surgery

Background: Cardiovascular and metabolic comorbidities are dramatically increased in severe obesity, a condition highly resistant to nonsurgical therapy. Objective: The objective was to identify predictors of weight loss and reversal of comorbidity in obese patients undergoing malabsorptive bariatric surgery. Design: Morbidly obese men and women (n = 107) were studied before and 2 y after biliopancreatic diversion (BPD). Body composition, serum lipid profile, oral glucose tolerance, and blood pressure were measured. Insulin sensitivity was determined by use of a euglycemic clamp. The length of the small intestine was measured during surgery. Results: Intestinal length was 671 ± 99 cm, and the residual absorbing intestine after BPD ranged from 54% to 24% of initial length. Patients lost an average of 36% of their initial weight, with ≈50% of them reaching a body mass index (in kg/m²) <30. Serum cholesterol decreased (from 4.58 ± 1.11 to 3.34 ± 0.73 mmol/L; P <0.0001), as did serum triacylglycerols (from 1.52 ± 0.59 to 0.88 ± 0.35 mmol/L; P <0.0001), whereas insulin sensitivity rose 150% (from 26 ± 4 to 64 ± 11 μmol · min ^-1 · kg fat-free mass^-1; P <0.0001). Diabetes (in 23% of patients before surgery) and hypertension (in 83%) were reduced (by 88% and 96%, respectively) after surgery. In a multivariate model (including sex, age, intestinal length, presence of diabetes, insulin sensitivity, and initial fat mass), age and diabetes were independent, negative predictors of weight loss, whereas initial fat mass was a strong positive predictor (r ² = 0.51). Conclusions: Two years after BPD in morbidly obese patients, comorbidities are largely corrected and insulin resistance is fully reversed despite persistent obesity. Initial fat mass, but not residual intestinal length, is the strongest predictor of weight loss after BPD.