Approximately 35% of U.S. adults are obese, and bariatric surgery is an effective treatment option. The three most common bariatric surgeries are sleeve gastrectomy, Roux-en-Y gastric bypass, and adjustable gastric banding. While previously thought to work by restriction of food intake or malabsorption, research now shows bariatric surgery reduces ghrelin and increases glucagon-like peptide to enhance weight loss. Obesity accounts for significant healthcare costs, and while bariatric surgery has costs, it may prove cost-effective in improving health outcomes.