Sleeve surgery, formally called vertical sleeve gastrectomy, is a weight loss procedure that permanently removes about 80% of the stomach. The remaining portion is shaped into a narrow tube roughly the size of a banana. It’s the most commonly performed bariatric surgery in the world, and it works through two mechanisms: physically restricting how much food you can eat at one time, and altering hunger hormones so you feel less appetite overall.
How the Procedure Works
The surgery is performed laparoscopically, meaning the surgeon works through several small incisions rather than one large opening. Using a stapling device, the surgeon divides the stomach vertically and removes the larger, curved portion (called the fundus) entirely from the body. What remains is a sleeve-shaped tube that holds significantly less food. The procedure takes 60 to 90 minutes, and most people stay in the hospital for one to two days afterward.
Unlike gastric bypass, sleeve surgery doesn’t reroute the intestines. Your digestive tract stays intact, which means food still follows its normal path from stomach to small intestine. This makes it a simpler operation with fewer potential complications related to nutrient absorption, though it’s still a major, irreversible surgery.
Why Removing the Fundus Changes Hunger
The curved portion of the stomach that gets removed isn’t just extra space. It’s where most of the body’s ghrelin is produced, the hormone responsible for stimulating appetite and signaling hunger to your brain. After sleeve surgery, ghrelin levels drop significantly, which is why most patients report a noticeable and lasting reduction in appetite. Studies show this effect persists at least two years after surgery, with patients eating smaller portions more regularly throughout the day rather than consuming large meals.
Leptin, another hormone tied to body fat levels, also decreases as patients lose weight. Meanwhile, adiponectin, a hormone that helps regulate blood sugar and fat metabolism, increases significantly. These hormonal shifts work alongside the physical restriction to support sustained weight loss in a way that dieting alone rarely achieves.
How Much Weight People Typically Lose
Weight loss after sleeve surgery is measured as a percentage of “excess weight,” which is the amount above what’s considered a healthy weight for your height. In a prospective study tracking patients over five years, the average excess weight loss was 82% at one year, 77% at three years, and 60% at five years. That first-year result brought the average patient’s BMI down to 26.4, which is just slightly above the normal range.
The pattern is consistent: most of the weight comes off in the first 12 to 18 months, and some regain is common in the years that follow. A five-year excess weight loss of 60% is still a substantial, life-changing amount for someone who started at a BMI of 40 or higher, but it’s worth knowing that long-term maintenance requires ongoing dietary discipline.
Effects on Diabetes and Blood Pressure
The benefits of bariatric surgery extend well beyond the number on the scale. Among patients with type 2 diabetes before surgery, 83% experienced complete resolution at one year, and that number held at 86% even at the five-to-seven-year mark. For hypertension, 69% of patients no longer had high blood pressure at one year. That rate dipped to 51% by the ten-to-twelve-year follow-up, suggesting some recurrence over time, but the initial improvements are striking.
These metabolic changes often begin before patients have lost most of their weight, which points to the hormonal and gut-signaling shifts triggered by the surgery itself, not just the calorie reduction.
Who Qualifies for Sleeve Surgery
Updated 2022 guidelines from the two major international bariatric surgery organizations lowered the eligibility threshold. Surgery is now recommended for anyone with a BMI above 35, regardless of whether they have any related health conditions. For people with a BMI between 30 and 35 who have metabolic diseases like type 2 diabetes, surgery is also recommended. And for those in that same 30 to 35 BMI range without metabolic disease, surgery should be considered if nonsurgical approaches haven’t produced meaningful or lasting results.
These thresholds represent a significant shift. For years, a BMI of 40 (or 35 with health problems) was the standard cutoff. The updated guidelines reflect growing evidence that the procedure’s benefits outweigh its risks at lower BMIs than previously thought.
Risks and Complications
The most serious surgical risk is a staple line leak, where the sealed edge of the remaining stomach doesn’t heal properly and allows digestive fluids to escape into the abdomen. This occurs in roughly 1 to 3% of procedures and can require additional operations, extended hospital stays, and prolonged antibiotic treatment. In severe cases, leaks are fatal in 5 to 10% of those who develop them, though that translates to a very small absolute number given the low leak rate overall.
The most common long-term issue is acid reflux. This is a significant concern: in one long-term follow-up study, the rate of GERD increased from about 7% before surgery to 50% at the last follow-up. Nearly half of patients who had no reflux before the procedure developed it afterward. For people who already have chronic reflux, surgeons often recommend gastric bypass instead, since that procedure tends to improve GERD rather than worsen it.
The Post-Surgery Diet Timeline
Recovery after sleeve surgery follows a strict, phased diet that gives the staple line time to heal. For the first two weeks, you’ll be on clear liquids only. From there, you move to a full liquid diet through about day 15. Weeks three and four introduce pureed foods, which have the consistency of baby food. Weeks five and six allow soft foods like scrambled eggs and cooked vegetables. After that, you gradually transition to regular solid foods, though portion sizes will be permanently smaller.
Each phase exists to protect the healing stomach. Eating solid food too early can stress the staple line and cause serious complications. Most patients find that by the time they reach solid foods, their relationship with eating has fundamentally changed. Portions that once felt normal now feel enormous, and hunger signals are muted in a way they weren’t before.
Lifelong Vitamin Supplementation
Because the stomach is so much smaller after surgery, you simply can’t take in enough food to meet all your nutritional needs through diet alone. Vitamin D and folate deficiencies show up in 93 to 100% of post-surgery patients who don’t supplement. Vitamins E and C are deficient in over half of patients, and vitamin B1 (thiamine) is low in the vast majority as well.
Daily supplementation with vitamin D, folate, B1, C, and E effectively corrects these shortfalls when taken consistently. Vitamin D is the most critical, since diet alone can’t come close to meeting the recommended intake after surgery. B12 deficiency, commonly associated with other bariatric procedures, turns out to be rare after sleeve surgery specifically, since the part of the stomach that absorbs B12 generally remains intact. Still, regular blood work and ongoing dietitian support are part of the long-term commitment that comes with this procedure.