What’s The Average Monthly Weight Loss After Gastric Sleeve? Most patients lose between 2-4 lbs (0.9-1.8kg) every week for about 6-12 months. This results in a monthly weight loss of about 8 to 16 pounds. More weight is lost in the first month than in any other month, mostly due to the way eating is structured in that month., Planning a weight-loss journey? Find out how much you can expect to lose with gastric sleeve surgery each month and set yourself up for success., Average weight loss after bariatric surgery varies by procedure. See typical results, phases of weight loss, and what leads to long-term weight control., , , .