What percentage of my weight should I expect to lose after bariatric surgery?

Depends on procedure. Weight loss is usually reported as % of excess weight lost over time. Bypass procedures usually produce more weight loss than banding procedures. Restrictive only procedures (banding) results in a typical weight loss of 40-60% of excess weight while procedures that combine a restrictive and malabsorptive component (bypass procedures) typically result in 50 to 70% excess weight loss.
Depends on OR. Most doctors calculate excess weight. If you are 5foot 5 in and 250 lb, your excess weight is 100 lb! your ideal weight is 150 lb (bmi=25). For bypass, usually lose 80% of excess body weight (80 lb in the above example). For sleeve, usually lose 70% of excess body wt. For band, usually lose 40% of excess weight. Hope that helps.
Bariatric weight los. Weight loss is variable depending on several factors but on average you will loose 75% of you excess weight with a bypass and 50-65% with band. The sleeve is somewhere between the band and bypass. These are only average numbers.