Putative Hormonal Mechanisms of Appetite Suppression Following LAGB: A Pilot Study

Brief Summary

Detailed Description

The expected duration of participation in the study is up to 6 months before bariatric surgery depending on participants' weight loss and insurance company requirements. A total of 10 patients will take part in this control group. The following procedures and tests will be done before surgery: routine standard tests required to be involved in the obesity surgery program (history and physical, blood work, ECG, nutritional assessment, psychological assessment and sleep study). During preoperative evaluation participants will be started on a medical weight loss diet with instructions provided by the program's endocrinologist, nurse practitioners and dietitians with the weight loss goals as stipulated by insurance companies and have a series of additional laboratory tests (blood work) done to test the hormonal response to weight loss. This blood work, which is drawn after eating a standardized meal, is the only experimental procedure of the entire study. We will be measuring several hormones associated with obesity including ghrelin, obestatin, peptide tyrosine tyrosine (PYY3-36), adiponectin, Glucagon-like peptide-1 (GLP-1), oxyntomodulin, leptin, insulin, glucose and pancreatic polypeptide (PP). Measurements will be done at 4 time intervals before surgery: at enrollment, +1-month, +3-months, and +6-months. This will allow us to look at hormone levels as participants gradually lose weight. If a participant reaches the insurance-dictated weight loss before 6 months, study participation will cease to allow the individual to proceed with surgery scheduling. Participants will be required to fast overnight prior to each visit. An intravenous line will be placed at 0800, all subjects will be fed a standard breakfast (35% fat, 15% protein, and 50% carbohydrate) consisting of 25% of estimated caloric needs for weight maintenance, which they will consume in 30 minutes or less. Blood will be taken beginning 30 minutes before the standardized meal, then at time 0, then 30, 60, 90, and 120 minutes after the meal for total ghrelin, pancreatic polypeptide, PYY3-36, active GLP-1, insulin, glucagon, leptin, oxyntomodulin, and glucose. An extra fasting sample will be obtained for lipids and total adiponectin. Three-quarters of a cup (148 mL) of blood will be drawn for analysis at each visit. Additionally, subjects will be asked to complete a Visual Analog Scale (VAS) three times during each research visit by placing a single vertical mark across a 100 mm in length line, with words anchored at each end, expressing the most positive and the most negative rating, to assess hunger, satiety, and fullness. Each visit will last approximately 4 hours.

Primary Outcomes