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.