The ideal weight to undergo gastric bypass surgery depends on your BMI and overall health. Typically, candidates have a BMI of 40 or higher or a BMI of 35–39.9 with obesity-related health conditions like diabetes, high blood pressure, or sleep apnea. At 340 lbs, you likely qualify for the procedure, though a consultation with a bariatric surgeon will confirm if it's the right option for you. In terms of weight loss, most patients lose around 60–80% of their excess weight within 12 to 18 months following gastric bypass. Excess weight is calculated as the amount of weight above a healthy BMI range for your height. For example, if your ideal weight is around 180 lbs, your excess weight is 160 lbs, and you could expect to lose approximately 96 to 128 lbs. While individual results vary, you might stabilize at a weight that falls within a BMI range of 25–30, depending on your commitment to lifestyle changes like exercise and a healthy diet. After significant weight loss, many individuals experience loose or excess skin, particularly around the abdomen. This is common after bariatric surgery because the skin often cannot fully contract after rapid weight loss. Whether you will need a tummy tuck depends on factors such as your skin’s elasticity, how much weight you lose, and your personal preferences. A tummy tuck can help by removing excess skin, tightening abdominal muscles, and improving the overall contour of your body. Your current efforts, including exercising and adopting healthier eating habits, are an excellent way to prepare for surgery and set the stage for long-term success. Quitting smoking and alcohol are also major steps that will positively impact your recovery and outcomes.