Changes in Gut Hormones, Body Composition and Energy Expenditure After Roux-en-Y
Condition: Obesity; Weight Loss
MeSH terms: Weight Loss
Study type: Interventional

Summary: 
      The purpose of this study is to gain a better understanding of the mechanism of weight regain
      through gut hormone (substances in the gut that control various functions of the digestive
      organs) and energy expenditure (the amount of energy a person uses to complete bodily
      activities).

      Our hypothesis is that gut hormone response might be different among subjects who are able to
      maintain weight loss and subjects with weight regain.

      For this study, investigators will measure fasting and postprandial (happening after a meal)
      gut hormones, bile acid, amino acids, vitamin B, vitamin D, myokines and adipokine levels in
      obese individuals who are at least 2 years after a Roux-en-Y gastric bypass (RYGB).
      Investigators will also measure resting metabolic rate (RMR) (the amount of energy expended
      daily) and body composition (the proportion of fat, muscle, and bone of an individual's
      body). The subjects body composition will be analyzed, including fat mass and fat free mass,
      by a Dual-Energy X-ray Absorptiometry (DEXA). This study will provide more information
      regarding the effect of RYGB on gut hormones, adipokines, bile acids, amino acids, and energy
      expenditure and body compositions.
    


Intervention name(s): Resting Metabolic Rate (RMR); Duel-energy x-ray absorptiometry (DEXA); Visual Analog Scale (VAS); Meal Stimulation Test
Intervention type(s): Other; Other; Other; Other
Intervention description(s): Each subject will have their resting metabolic rate (RMR) measured. The RMR is assessed by indirect calorimetry measured with the metabolic cart. Oxygen consumption is converted into kilocalories. Subjects will be advised to avoid strenuous exercise for at least 48 hours prior to participation in the study and to sleep at least 6-8 hours the night before. Smoking and consuming caffeine will be prohibited 12 hours before the study begins.; During a separate appointment on the same day, or within 7 business days if same day is not possible, a body compositions analysis, including fat mass and fat free mass, will be assessed by dual-energy x-ray absorptiometry (DEXA), using a Hologic system.; Subjects will be asked to complete a 100-mm Visual Analog scale (VAS) to assess their appetite. The VAS will be completed prior to the meal stimulation test and at 30-minutes, 1-hour, 90 minutes and 2-hours after the meal. The VAS will contain questions assessing food intake, appetite, and hunger.; Subjects will consume a mixed-nutrient liquid meal 240-ml in 20 minutes. Prior to the meal stimulation test, a baseline 10-ml blood sample will be collected. The, during the meal stimulation test, 10-ml venous blood sample will be collected at 30 minute intervals up to two hours, for a total of 5 samples including the baseline sample. The blood samples will be used to measure fasting blood glucose, adipokines, myokines, gut hormones, amino acids, bile acids, vitamin B and vitamin D analysis with the appropriate assay method.
Other intervention name(s): Hologic Discovery A serial # 82364A version 13.3
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Weight regain; Sustain weight loss; Weight loss; Gut hormones