Cerebrospinal Fluid Biomarkers in Bariatric Surgery

Peripheral metabolic signals communicate levels of energy stores to the brain and elicit a host of neuronal responses that maintain energy balance; such regulatory mechanisms make it difficult to maintain diet-induced weight loss. The goal is to understand how these central regulatory mechanisms are circumvented following surgical alterations in the gut in subjects after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (SG) compared to carefully matched diet- induced weight loss controls who achieve weight loss on a low calorie liquid diet. Surgery participants will be patients who have already chosen to have a bariatric surgery procedure with their doctor. Diet participants will be provided with the low calorie liquid diet for approximately 3 months and will be monitored weekly throughout the study. Surgery participants will be studied at 3 time-points: 1. Before the intervention 2. After surgery at 10-15% weight loss 3. At 12 months after surgery Low calorie diet participants will be studied at 2 time-points: 1. Before intervention 2. At 10-15% weight loss (approximately 12 weeks on the diet) At each time-point subjects will have a lumbar puncture (spinal tap) for cerebrospinal fluid (CSF) sampling and blood will be collected in the fasting state and in response to a liquid meal challenge. Body weight, waist and hip circumference will be measured.