The greatest weight loss after bariatric gastric bypass surgery usually occurs in the first year to 18 months following bariatric gastric bypass or other weight loss surgery. The first several months after a bariatric gastric bypass surgery, the weight loss may be rapid, but then the weight loss will plateau with intermittent peaks and lots of weight loss valleys. Eventually, the weight loss curve continues to travel downward. Five years after the bariatric gastric bypass surgery procedure obese patients have usually lost 50% - 75% of their excess weight and 50 to 60% weight loss after the vertical banded gastroplasty surgical procedure. Many patients regain some of this weight, but few ever regain it all.