Caloric Intake Capacity as Measured by a Standard Nutrient Drink Test Helps to Predict Weight Loss after Bariatric Surgery

Background Instruments that enable to select individuals that will benefit most from bariatric surgery (BS) are necessary to increase its cost-efficiency. Our goal was to assess if intake capacity, measured with a standardized test, predicts response to BS. Methods Patients with criteria for BS were randomly allocated to laparoscopic gastric bypass (LRYGB) or sleeve gastrectomy (LSG). We measured caloric intake capacity before and 1 year after surgery using a standardized nutrient drink test. We evaluated if pre-surgery satiation could predict satiation and weight loss (%) 1 year after surgery using multiple regression modeling. Descriptive statistics are given as mean +/- SD. Results Fourteen women (48 +/- 9 years old, BMI 41 +/- 3 kg/m(2)) were evaluated before and 11 +/- 2.6 months after surgery (seven LRYGB, seven LSG). Caloric intake capacity diminished after surgery (-950 +/- 85 kcal on average [70 +/- 8 % decrease over basal intake capacity]; p=0.002) and similarly in both LRYGB (72 +/- 7 % decrease) and LSG groups (68 +/- 8 % decrease); p=0.5. There was a significant weight reduction after surgery (-32 +/- 10 kg [30 +/- 8 % of total basal weight]) with a mean post-surgery BMI of 29 +/- 2 kg/m(2). The best predictive model of weight loss (%) after surgery (R-2=89%, p=0.0009) included: BMI (p=0.0004), surgery type (p=0.01) and pre-surgery intake capacity (p=0.006). Weight loss was higher in heavier patients and those undergoing LRYGB. Patients with higher intake capacity had a poorer outcome independently of basal BMI and surgery type. Conclusions Caloric intake capacity, as measured by a standard nutrient drink test, helps to predict weight loss after bariatric surgery. This test might be useful in algorithms of obesity treatment decision.