Diet-induced Thermogenesis in Patients With Postoperative Roux-in-Y Gastric Bypass (RYGBP) Weight Regain
Condition: Obesity; Bariatric Surgery Candidate; Protein-energy; Imbalance
Study type: Interventional

Summary: 
      Introduction: According to the National Health and Nutrition Examination Survey 2009-2010, 78
      million American adults are obese. Bariatric surgery can provide for a sustained long-term
      weight loss and the metabolic change caused by the surgery seems to be the main cause of this
      loss. Cross-sectional, prospective and experimental studies, carried out during the
      post-operative period of Roux-en-Y Gastric Bypass surgery (RYGBP) have shown an increase of
      over 200% in energy expenditure after meals Diet-induced Thermogenesis (DIT), a specific
      component of energy expenditure) when compared with obese patients. However, despite this
      metabolic improvement, 20-50% of the patients can suffer weight regain about 2 years after
      surgery. So one question whether such metabolic benefits remain active following
      post-operative weight regain, or if the disappearance or decrease of these metabolic benefits
      may be seen as causes of this weight regain.

      Objective:To evaluate whether there are DIT differences between patients who maintained
      weight loss and those who regained weight in the late postoperative (postop) period of RYGBP
      and those who continue with preoperative (preop) obesity.
    

Detailed description: 
      Methods: This cross-sectional study evaluated three female groups: 1) Postop RYGBP patients
      operated at least 2 years previously, with healthy weight (at least 50% loss of excess
      weight) - HW group ; 2) Clinically severe obese patients (BMI > 40 kg/m2, without
      co-morbidities or > 35 kg/m2 with co-morbidities) - OB group; 3) Post-op RYGBP WR patients
      (at least 10% above post-op minimum weight and less than 50% loss of preop excess weight) -
      WR group. All patients, from a private practice in Brasilia, were given indirect calorimetry
      examinations (GERATHERM RESPIRATORY®) measuring resting metabolic rate (RMR), respiratory
      exchange rate (RER) and DIT and collected urine during 24 hours for analysis. Immediately
      after RMR measurement, a solid mixed meal was served (270 kcal: 62% carbohydrate, 12% protein
      and 26% lipid). Remove? After ten minutes, successive PP energy expenditure measurements were
      taken (after some minutes, viz): 10-20, 20-30, 30-40, 60-70, 70-80, 80-90, 110-120, 120- 130,
      130-140, 160-170 and 170-180, accompanying a 3-hour measurement period. DIT, calculated for
      each interval, followed this equation: DIT = PP Metabolic rate (MR) time interval - RMR.
      Correct? Mean areas under the curve (AUC) of all groups and baseline time measurements were
      compared using the analysis of variance test (ANOVA). Between-group longitudinal changes were
      tested using a mixed-effects model analysis of variance for repeated measures. Showing a
      p-value < 0.05, a Bonferroni correction was used. AUC was calculated by trapezoidal rule,
      considering significant a value of p <0.05.

      Results: 45 patients participated (HW 21, OB 13, WR 11). Mean group age was 37.00 ± 6.98
      years , 38.72 ± 7.01 years, and 37.88 ± 6.39 years, respectively. I changed the sequence to
      match the original. RER values increased significantly in all groups from baseline until
      final measurements. Metabolic rate (MR) adjusted for body weight (BW-adjusted MR (MR/kg)?)
      was not significant in the OB group at any PP moment compared to baseline. The HW and WR
      groups showed significant increase until final measurements. Mean AUC values for RER and RMR
      in absolute terms did not differ between groups (p = 0.3111 and p = 0.1131, respectively).
      (Two p values for how many groups ? 2 or 3?) Mean AUC values for BW-adjusted MR (kcal/kg)?
      differed between groups, where the average AUC value was significantly greater in the HW
      group than in the WR and the OB groups (p <0.0001 for both). Mean AUC value for BW-adjusted
      MR in the WR group was not significantly different from the OB group (p = 0.6369).
    

Intervention name(s): patients eat a mixed solid meal
Intervention type(s): Other
Intervention description(s): The three groups were given an indirect calorimetry examination to measure their resting metabolic rate (RMR), respiratory exchange rate (RER) and DIT. The patients collected urine during 24 hours for urinary nitrogen analysis. Immediately after the RMR measurement, patients received a solid mixed meal (270 kcal, with 62% carbohydrate, 12% protein and 26% lipid). Ten minutes after beginning this food intake, postprandial (PP) energy expenditure measurements were taken in the following sequences (in minutes): 10-20, 20-30, 30-40, 60-70, 70-80, 80-90, 110-120, 120- 130, 130-140, 160-170 and 170-180.The DIT was calculated for each time interval.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Keywords: metabolism; Diet Induced Thermogenesis; weight regain; energy expenditure; bariatric