SIPS stands for Stomach Intestinal Pylorus-Sparing surgery, a weight loss procedure that combines two mechanisms: it shrinks the stomach and reroutes part of the small intestine so your body absorbs fewer calories from food. It was developed as a simpler, streamlined version of the traditional duodenal switch, one of the most effective but also most complex bariatric surgeries. Both the International Federation for the Surgery of Obesity (IFSO) and the American Society for Metabolic and Bariatric Surgery (ASMBS) have endorsed the procedure since 2020.
How the Procedure Works
SIPS has two parts, both performed laparoscopically through small incisions. First, the surgeon creates a sleeve gastrectomy, removing roughly 80% of the stomach to form a narrow, banana-shaped tube. This dramatically limits how much food you can eat at one sitting.
The second part is the intestinal reroute. The surgeon divides the first portion of the small intestine just past the pylorus (the valve at the bottom of your stomach) and connects it to a lower section of the intestine. This means food bypasses a large stretch of the gut where calories and fat would normally be absorbed. The pylorus itself stays intact, which is where the “pylorus-sparing” name comes from. Preserving this valve helps regulate how quickly food leaves your stomach and reduces the dumping syndrome that can happen with gastric bypass.
The key simplification compared to the traditional duodenal switch is that SIPS uses a single connection point between the intestine and the stomach, rather than two. Fewer connections mean a shorter, less technically demanding operation with fewer places where complications like leaks can develop.
SIPS vs. the Traditional Duodenal Switch
The traditional biliopancreatic diversion with duodenal switch (BPD-DS) has long been considered the most powerful bariatric procedure for weight loss, but its complexity and complication profile have limited its use. SIPS was designed to deliver similar results with a less involved surgery. A retrospective comparison at a single institution found that at two years, patients who had the traditional duodenal switch lost slightly more weight: an average BMI drop of 23.3 points compared to 20.3 points with SIPS. That difference is meaningful but relatively modest, and many surgeons consider the tradeoff worthwhile given the simpler operation.
SIPS is also sometimes called SADI-S (single anastomosis duodeno-ileal bypass with sleeve gastrectomy) or SADS. The names refer to essentially the same concept, though individual surgeons may vary slightly in technique. If you see these terms used interchangeably in research or clinic brochures, they’re describing the same family of procedure.
Weight Loss Results
SIPS produces substantial weight loss, particularly for people with very high BMIs. The procedure has been especially successful in the “super-obese” population, defined as a BMI over 50. According to the 2023 IFSO position statement reviewing the broader evidence on this procedure type, average total body weight loss ranged from 22.8% to 47.8% at two years, and average excess weight loss ranged from 62.4% to 102% at one year. That upper range, exceeding 100%, means some patients lost more than just their excess weight.
These numbers place SIPS among the most effective bariatric procedures available, generally outperforming sleeve gastrectomy alone and comparable to gastric bypass, with some data suggesting it may exceed bypass results over time. The combination of a smaller stomach and significant calorie malabsorption gives SIPS two independent drivers of weight loss, which is why it tends to produce more dramatic results than restriction-only procedures.
Who Is a Candidate
Eligibility for SIPS follows the same general criteria as other bariatric surgeries. You typically need a BMI of 40 or higher, or a BMI of 35 or higher with at least one obesity-related health condition like type 2 diabetes, high blood pressure, or sleep apnea. The approval process involves a medical evaluation, lab work, and a mental health assessment. You’ll also need to demonstrate readiness to commit to long-term lifestyle changes in diet and physical activity.
Because SIPS is particularly effective for people at the highest weight categories, surgeons often recommend it specifically for patients with a BMI over 50 who may not achieve sufficient results from a sleeve gastrectomy or gastric bypass alone. It’s also chosen for its benefits in resolving type 2 diabetes and high blood pressure, conditions that often improve or fully resolve after the procedure.
Recovery and Hospital Stay
Like most modern bariatric procedures, SIPS is performed laparoscopically, which means a shorter hospital stay and faster recovery than open surgery. Most patients spend one to two days in the hospital. You’ll be asked to sit up, dangle your feet, and stand at your bedside the evening of surgery, then walk the following day. After that, the goal is walking at least three times daily.
For the first three to six weeks, strenuous activity is off limits, and you should avoid lifting anything heavier than 15 to 20 pounds. By six weeks, you should be walking 30 to 45 minutes a day. If you have joint problems in your ankles, knees, or hips, water exercises are usually safe once your incisions have healed, typically three to four weeks out.
The Post-Surgery Diet
Your diet after SIPS follows a gradual progression that takes several months. Immediately after surgery, you start with clear liquids only. Once you’re home from the hospital, you can begin adding thicker liquids. Two weeks after surgery, you move to blended and puréed foods, taking very small bites and chewing thoroughly. A good rule during this phase is no more than two bites every 20 minutes when trying a new food.
From weeks two through eight, you’ll continue with soft, easily digestible foods in small portions. Between two and six months, your diet gradually expands. By six months and beyond, you settle into a long-term pattern of roughly 900 to 1,000 calories per day spread across three meals and one to two snacks. Protein intake becomes critical because the malabsorptive component of SIPS means your body is less efficient at extracting nutrients from food.
Lifelong Vitamin and Mineral Supplements
This is the part of SIPS that requires the most ongoing commitment. Because food bypasses a significant portion of your small intestine, your body absorbs fewer vitamins and minerals from what you eat. Lifelong supplementation isn’t optional. The American Society for Metabolic and Bariatric Surgery’s nutritional guidelines for the closely analogous duodenal switch procedure outline a substantial daily regimen:
- Calcium: 1,800 to 2,400 mg per day from all sources, the highest requirement of any bariatric procedure
- Vitamin D: at least 3,000 IU daily, with blood levels monitored to ensure they stay above 30 ng/mL
- Iron: 45 to 60 mg of elemental iron daily, especially important for menstruating women
- Vitamin A: 10,000 IU daily
- Vitamin K: 300 micrograms daily
- Vitamin B12: 350 to 500 micrograms daily (as a dissolving tablet, sublingual, or liquid)
- Zinc: 16 to 22 mg daily (200% of the standard recommended amount)
- Copper: 2 mg daily
- Thiamin (B1): ideally 50 mg daily from a B-complex supplement
- Folate: 400 to 800 micrograms daily
Skipping these supplements puts you at risk for serious deficiencies over time, including bone loss from inadequate calcium and vitamin D, anemia from low iron or B12, and neurological problems from thiamin deficiency. Regular blood work, typically every three to six months in the first year and annually after that, is essential to catch any gaps before they cause symptoms.
Risks and Complications
SIPS carries the general risks of any major abdominal surgery performed under anesthesia: blood clots, infection, and bleeding. The procedure-specific risk that surgeons watch most closely is an anastomotic leak, where the connection between the intestine and stomach doesn’t seal properly. Across bariatric bypass procedures, leak rates run between 1.5% and 6%, depending on the type of surgery. The single-connection design of SIPS was specifically intended to reduce this risk compared to the traditional duodenal switch’s two connection points.
Nutritional deficiencies are the most common long-term complication and are essentially guaranteed without consistent supplementation. Bile reflux, where digestive fluid backs up into the stomach or esophagus, can also occur because of the intestinal rerouting. Some patients experience increased bowel frequency or looser stools, particularly with high-fat meals, because undigested fat passes further through the intestines before being absorbed. These effects tend to be less severe than with the traditional duodenal switch but more noticeable than after a sleeve gastrectomy or gastric bypass.