Changes in Body Composition Following Bariatric Surgery
Condition: Obesity
MeSH terms: Obesity
Study type: Observational [Patient Registry]

Summary: 
      Obesity is an important public health issue worldwide. In the United States, the percentage
      of overweight and obese adults increased from 47 and 15%, respectively, to 69 and 36% in the
      last 40 years. Medically supervised attempts at weight loss are fraught with failures and
      recidivism. Surgical approaches to this important issue are both durable and effective. The
      gold standard approach to the surgical treatment of obesity and the attendant medical
      comorbidities is the laparoscopic roux-en-y gastric bypass (RYGB) and the laparoscopic sleeve
      gastrectomy (LSG). The mechanisms by which these two operations work and the associated side
      effects are not completely understood. It is established that the RYGB induces changes in
      both the fatty tissue mass (FTM) and lean body mass (LBM) post-operatively. This is
      associated with decreases in bone mineral density, basal metabolic rate, and potentially the
      ability to maintain weight loss. There is only incomplete information on the influence that
      the LSG has on body composition. This study proposes an evaluation of the changes in body
      composition that occurs following these two disparate operations. Using serial measurements
      by the BodPod and collecting information on the patients' dietary intake, exercise habits and
      comorbidity resolution, this study will help to better define the influence that the LSG has
      on body composition. It is hypothesized that the addition of a malabsorptive component will
      result in increased speed weight loss and overall weight loss which will have a negative
      impact in the preservation of lean tissue mass for the patient. This information can then be
      used by bariatric surgeons to better cater the surgical procedure and post-operative plan to
      the patient's body make up and medical comorbidities.
    

Detailed description: 
      Procedures

        -  All patients will undergo a bariatric surgery. The decision to undergo weight loss
           surgery and the operation chosen will both occur independent of and prior to enrollment
           in the study. The University of Iowa is a Bariatric Center of Excellence with three
           active, board-certified bariatric surgeons.

        -  Serial BodPod examinations will be performed on each patient. The BodPod is a
           commercially available device produced by Cosmed. It uses whole-body densitometry to
           determine body composition. To do this, it takes small changes in the volume of air in
           the BodPod chamber and records the associated changes in pressure. The pressure change
           typically goes unnoticed and is equivalent to the change in pressure while moving from
           the first floor to the second floor in an elevator. The entire process takes
           approximately five minutes with two minutes spent within the machine. The computer will
           then use mathematical formulas to calculate various body composition values.

        -  Laboratory analysis - There is a battery of labs that are ordered in both the
           pre-operative and post-operative time frame. These labs are ordered independent of the
           patient's participation in the study. These labs are ordered to assist in the management
           of the patient's medical comorbidities and to assess for adequate nutritional intake.
           These labs will also be recorded in the research database to assist in quantifying the
           degree of resolution of medical comorbidities.

        -  Queries on nutritional intake and exercise will be made at each post-operative
           appointment. The intake of protein is an important variable and may influence
           maintenance of lean tissue mass. Exercise is an important component of the
           post-bariatric weight loss program. This also will influence the changes in lean tissue
           mass.
    

Intervention name(s): Bariatric Surgery
Intervention type(s): Procedure
Intervention description(s): Patients enrolled will undergo either a laparoscopic Roux-en-y Gastric Bypass or laparoscopic Sleeve Gastrectomy. The determination of which operation performed will be made independent of patients' enrollment in the study.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The population consists of individuals who meet the NIH consensus statement for the
        surgical treatment of obesity. These individuals will have a BMI greater than 35 kg/m2 and
        a medical comorbidity or 40 kg/m2. These subjects will have voluntarily initiated a
        consultation for bariatric surgery and completed the pre-bariatric surgery weight
        management program. After failing this program, the patients will undergo surgical
        consultation for bariatric surgery. It is only after this consultation that the subjects
        will be approached for enrollement in the study.
      
Keywords: Obesity; Bariatric Surgery; Roux-en-y Gastric Bypass; Sleeve Gastrectomy