If you are not severely overweight, the gastric balloon can help you lose your appetite long enough to inch closer to your desired weight. If your BMI is high, the balloon isn’t a very useful answer for your chronic weight problem. Studies show that after six months of a gastric balloon in the stomach, patients can expect to lose about a third of their excess weight; however, by the end of a year, the weight loss is only 10 percent. Long-term weight loss from gastric sleeve ranges from 50 to 70 percent of excess weight.