I doubt that anyone has a firm number to answer that question. In my own experience, liposuction tends to motivate people to maintain their new appearance through a healthy diet and exercise. Good luck!
If you're talking about lean body weight and not immediate increases in weight due to fluid retention from the operation I'm not sure I know the answer. In my practice most patients undergoing liposuction have motivation for improvement in body contour and end up losing weight subsequently.