Background and Aims The mechanism of weight loss with the intra-gastric balloon (IGB) is thought to be a decrease in gastric emptying (GE); however the evidence is conflicting. Nausea, abdominal pain, and gastroesophageal reflux disease (GERD) can cause intolerance resulting in early removal. This is demoralizing for the patient and costly for the healthcare system. The ability to predict which patients will have superior weight loss and tolerance is invaluable. We sought to investigate if the IGB induced weight loss by reducing GE and the effect of the IGB on the DeMeester score. Methods We retrospectively reviewed prospectively collected data for patients undergoing IGB placement at a single hospital. Manometry and pH studies were performed before and with the IGB in place. Weight was measured at baseline, at removal, and 6 months later. Adverse events leading to early removal were recorded. Results Twenty-four patients were evaluated. There was a statistically significant decrease in GE for solids with the IGB (117.92 +/- 150.23 vs 281.48 +/- 206.49 min; p = 0.0048), but not for liquids (54.44 +/- 17.97 vs 56.08 +/- 43.96 min; p = 0.7228). The lower esophageal sphincter (LES) pressure did not change significantly with placement of the IGB (17.76 +/- 7.39 vs 14.74 +/- 7.24 mmHg; p = 0.09). On multivariate analysis, increase in DeMeester score was associated with total body weight loss (p = 0.0125) and change in GE (p = 0.038) independently. Conclusion The IGB delays GE for solids, but not for liquids, and increases the DeMeester score by a mechanism other than a loss of LES pressure.