Definition of Gastroesophageal reflux disease:

Gastroesophageal reflux disease (GERD) is a condition in which food or liquid travels backwards from the stomach to the esophagus (the tube from the mouth to the stomach). This action can irritate the esophagus, causing heartburn and other symptoms.

Causes, incidence, and risk factors:

Gastroesophageal reflux is a common condition that often occurs without symptoms after meals. In some people, the reflux is related to a problem with the lower esophageal sphincter, a band of muscle fibers that usually closes off the esophagus from the stomach. If this sphincter doesn't close properly, food and liquid can move backward into the esophagus and may cause the symptoms.

The risk factors for reflux include hiatal hernia, pregnancy, and scleroderma.

A number of studies suggest that obesity contributes to gastroesophageal reflux. For instance, the Nurses Health Study found that being overweight or obese significantly increased reflux symptoms in women. (Women who lost weight in the study, meanwhile, had fewer symptoms.)