Over half of morbidly obese individuals have GERD
This is related to relaxation of the lower esophageal sphincter with or without the presence of a hiatal hernia. Obesity is associated with increased intra-abdominal pressure leading to increased pressure at the gastro-esophageal junction and the higher the BMI, the higher the risk of GERD.
Weight loss can lead to a reduction in intra-abdominal pressure which decreases acid production and increases the rate of gastric emptying which improves symptoms of reflux. 1/3 of patient will still have symptoms, another 1/3 note improvement, and the final third can develop reflux. It is important to have an appropriate evaluation by a bariatric surgeon when choosing your bariatric surgery. If you have severe reflux prior to weight loss, the best bariatric procedure is the gastric bypass which creates a small gastric pouch with very few acid producing cells while the acid producing portion of the stomach is now disconnected from the esophagus.