There are four main types of bariatric surgery performed today: sleeve gastrectomy, Roux-en-Y gastric bypass, biliopancreatic diversion with duodenal switch, and a newer simplified version called SADI-S. Each works differently, produces different levels of weight loss, and carries its own trade-offs. A non-surgical endoscopic option also exists for people with lower BMI who don’t qualify for or want traditional surgery. Here’s how they compare.
Sleeve Gastrectomy
Sleeve gastrectomy is the most commonly performed bariatric procedure. A surgeon removes roughly 80% of your stomach, leaving behind a narrow, banana-shaped tube. This does two things: it physically limits how much food you can eat at one sitting, and it removes the portion of the stomach that produces most of your hunger hormones. That hormonal shift is a big part of why the surgery works. You don’t just eat less because your stomach is smaller; your brain actually receives fewer hunger signals.
Average weight loss with a sleeve is 25% to 30% of total body weight in the first one to two years, and that number holds steady at five years. So if you weigh 300 pounds, you’d typically lose 75 to 90 pounds. Because the intestines aren’t rerouted, the risk of nutritional deficiencies is lower than with bypass procedures, though you’ll still need daily vitamin and mineral supplements for life.
Roux-en-Y Gastric Bypass
Gastric bypass has been performed for more than 50 years, making it the most studied bariatric operation. The surgeon creates a small egg-sized pouch at the top of the stomach and disconnects it from the rest. Then a section of the small intestine is rerouted and attached directly to that pouch, forming a Y-shaped connection (which is where the name “Roux-en-Y” comes from). Food skips the larger portion of the stomach entirely and enters the intestine further downstream.
This gives gastric bypass two mechanisms: restriction (the tiny pouch limits how much you eat) and malabsorption (food bypasses part of the intestine, so fewer calories and nutrients are absorbed). The result is typically more weight loss than a sleeve. You can expect to lose about 70% or more of your excess weight within two years.
Gastric bypass also appears to have a stronger effect on type 2 diabetes than the sleeve. In one study, 75% of bypass patients maintained diabetes remission long-term, compared with about 35% of sleeve patients. Even among people who regained all their lost weight after bypass, roughly 60% still kept their diabetes in remission at five years. That metabolic benefit seems to come from changes in gut hormones and how food interacts with the intestine, not just from weight loss itself.
The trade-off is a higher risk of nutritional deficiencies and a condition called dumping syndrome, where food moves too quickly into the small intestine, causing nausea, diarrhea, or vomiting after eating sugary or high-fat foods.
Duodenal Switch (BPD/DS)
The duodenal switch is the most aggressive standard bariatric procedure. It starts with a sleeve gastrectomy, then adds an extensive intestinal bypass. The first portion of the small intestine is separated from the stomach, and food is rerouted so it travels through a much shorter stretch of intestine before meeting digestive enzymes. This creates a “common channel” of only about 125 to 150 centimeters where calories and nutrients are actually absorbed.
At five years, patients average 42% total weight loss. That’s the highest of any standard procedure. But the extensive bypass means significantly more nutritional risk. Over half of duodenal switch patients experience nutritional complications, requiring diligent, lifelong supplementation with higher doses of vitamins and minerals.
SADI-S: The Simplified Version
A newer modification called SADI-S (single-anastomosis duodeno-ileal bypass with sleeve gastrectomy) simplifies the duodenal switch by using one intestinal connection instead of two and leaving a longer common channel of 250 to 300 centimeters. This preserves most of the weight loss benefit while dramatically cutting nutritional complications. Ten-year data shows nearly identical long-term results: 47% total weight loss for SADI-S versus 46% for traditional duodenal switch. But nutritional complication rates drop from 53% to just 16%. For that reason, SADI-S is increasingly preferred over the classic duodenal switch.
Endoscopic Sleeve Gastroplasty
Endoscopic sleeve gastroplasty isn’t technically surgery. Instead of cutting and removing stomach tissue, a doctor uses a flexible scope passed through your mouth to place sutures along the inside of your stomach, folding it inward to create a smaller, tube-like shape. There are no external incisions, and the stomach’s blood supply and nerve connections stay intact.
This option targets people with class I or class II obesity (roughly a BMI of 30 to 40) who either don’t qualify for traditional bariatric surgery or prefer a less invasive approach. In the short term, weight loss results are comparable to a surgical sleeve for this BMI range, and the procedure is less likely to cause acid reflux. Recovery is faster, but long-term data is still more limited than for the surgical options.
Adjustable Gastric Banding
The adjustable gastric band (often called the Lap-Band) was once one of the most popular bariatric procedures. A silicone band is placed around the upper stomach to create a small pouch, and the band can be tightened or loosened through a port under the skin. It sounded appealing because it was reversible and required no cutting of the stomach or intestines.
In practice, weight loss was modest compared to other procedures, and complication rates over time were high. Band slippage, erosion into the stomach wall, and port problems led many patients to need removal and conversion to a sleeve or bypass. Only 773 banding procedures were performed in the United States in 2023, making it a near-obsolete option.
Who Qualifies for Bariatric Surgery
Updated guidelines from the major surgical societies recommend bariatric surgery for anyone with a BMI of 35 or higher, regardless of whether they have other health conditions like diabetes or high blood pressure. For people with a BMI between 30 and 35 who do have metabolic disease, surgery should still be considered. For Asian populations, the thresholds are lower: clinical obesity starts at a BMI of 25, and surgery is recommended at 27.5 or above.
Recovery and Dietary Changes
Recovery follows a similar pattern for all surgical procedures. Most are done laparoscopically, meaning small incisions and a hospital stay of one to three days. The dietary progression afterward is structured in three phases. Phase I is a liquid-only diet lasting about 7 to 10 days. Phase II introduces soft foods for roughly four weeks. Phase III is a “regular” bariatric diet with normal food textures, though portions remain much smaller than before surgery.
Long-term, all bariatric procedures require daily vitamin and mineral supplements. At minimum, you’ll need calcium, vitamin D, vitamin B12, iron, and a multivitamin. The more intestinal bypass involved, the more supplements you’ll need and the higher the doses. Duodenal switch patients require substantially more calcium (1,800 to 2,400 mg per day versus 1,200 to 1,500 mg for a sleeve or bypass) along with higher doses of fat-soluble vitamins like A and K. Bypass and duodenal switch patients also need more iron and zinc than sleeve patients.
Skipping supplements isn’t optional. Deficiencies in B12 can cause nerve damage, low iron leads to anemia, and inadequate calcium and vitamin D weaken bones over time. Regular blood work to check nutrient levels is a permanent part of life after any bariatric procedure.
Choosing the Right Procedure
The right surgery depends on your BMI, your health conditions, and how much nutritional monitoring you’re willing to commit to. A sleeve is the simplest option with good, durable weight loss and the lowest supplement burden. Gastric bypass produces more weight loss and stronger diabetes remission but requires closer nutritional follow-up. The duodenal switch or SADI-S produces the most weight loss and is typically reserved for people with a BMI over 50 or severe metabolic disease, but demands the most rigorous lifelong supplementation. Endoscopic sleeve gastroplasty fills a niche for people with lower BMI who want a non-surgical approach.
Your surgical team will help match the procedure to your specific situation, factoring in your starting weight, existing health conditions, previous abdominal surgeries, and personal preferences around risk and lifestyle changes.