SADI-S

What SADI-S Does

SADI-S stands for Single Anastomosis Duodeno-Ileal Bypass with Sleeve Gastrectomy. It was developed in 2007 by Dr. Andrés Sánchez-Pernaute as a simplified version of the traditional duodenal switch — designed to keep the metabolic power of that procedure while reducing its surgical complexity and nutritional risks.

The operation has two parts. The first is a sleeve gastrectomy — about 80% of the stomach is removed, which limits how much you can eat and lowers the hunger hormone ghrelin. The second part is an intestinal bypass. Just below the stomach, the small intestine is divided and reconnected to a loop of intestine measured approximately 250–300 cm from the end of the small bowel. Food travels from the stomach directly into the lower portion of the small intestine, bypassing most of the section where calories and nutrients are absorbed.

That bypass is what makes SADI-S fundamentally different from sleeve gastrectomy or gastric bypass. A standard bypass reroutes part of the intestine. SADI-S reroutes substantially more — which is why the weight loss is greater and the metabolic changes, particularly for diabetes, are more profound. It's also why nutritional management after surgery requires more attention than after a standard sleeve or bypass.

How SADI-S Differs from Traditional Duodenal Switch

The traditional duodenal switch is the more aggressive procedure. It uses two separate intestinal connections and a shorter common channel, which means more calories and nutrients are bypassed. That translates to slightly more weight loss than SADI-S — but also significantly higher rates of serious nutritional complications.

A 10-year matched study published in 2025 comparing SADI-S to traditional DS found that the weight loss difference at a decade was not statistically significant: 47.3% total body weight loss with SADI-S versus 45.7% with DS. The nutritional picture was dramatically different: malnutrition requiring treatment occurred in 15.6% of SADI-S patients versus 53.5% of traditional DS patients. That gap is the core of why Dr. Brown's position is what it is — the traditional DS produces a modest additional weight loss benefit that does not justify the substantially higher risk of serious nutritional complications for most patients.

SADI-S is not a watered-down version of DS. It's a deliberate simplification that preserves the metabolic power of the duodenal switch family while removing the complications that make traditional DS difficult to manage long-term. For most patients who need this level of intervention, it's the right procedure.

What Results to Expect

In our practice, SADI-S patients typically lose 75–80% of their excess weight. Most of that loss happens in the first twelve to eighteen months. Many patients continue losing past two years. For someone with 150 pounds of excess weight, that means losing 110–120 pounds — results that sleeve or gastric bypass cannot reliably match at very high BMIs. Long-term data from published series confirms durable weight loss well past the five-year mark in patients who stay engaged with follow-up.

Type 2 diabetes responds particularly well. A five-year study of SADI-S outcomes found 92% overall diabetes remission — including 85% remission in patients who were insulin-dependent before surgery. Blood sugar often starts improving within days of surgery, before significant weight loss has occurred. The metabolic changes that drive this happen through hormonal mechanisms, not just calorie reduction — which is why SADI-S is particularly compelling for patients whose diabetes has been hard to control despite medication.

High blood pressure, sleep apnea, and high cholesterol also respond well. For patients at BMI 50 and above dealing with multiple serious health conditions, SADI-S offers the best realistic chance at meaningful, lasting improvement across all of those conditions simultaneously.

Who Is a Candidate for SADI-S

SADI-S is best suited for patients with a BMI of 50 or above, or patients in the mid-to-high 40s with serious metabolic disease — particularly Type 2 diabetes, especially if insulin-dependent. The degree of intervention should match the degree of disease. For patients at BMI 35–45 without major metabolic disease, sleeve gastrectomy or bypass will typically produce adequate results without the additional nutritional requirements that SADI-S carries.

SADI-S is also a strong option for patients who had a sleeve gastrectomy years ago and have experienced significant weight regain or inadequate metabolic improvement. Converting from sleeve to SADI-S as a second-stage procedure is a well-established pathway. Revision surgery carries more risk than a first procedure — but for the right patient, it's the appropriate next step.

SADI-S is not appropriate for patients with significant acid reflux, Barrett's esophagus, or large hiatal hernias. Unlike sleeve gastrectomy, SADI-S tends to improve or remain neutral on reflux — but starting with severe, uncontrolled reflux changes that calculus. Those patients are generally better served by Roux-en-Y gastric bypass. This is one of the first things we evaluate when a patient presents as a SADI-S candidate.

Factors that may disqualify a patient include severe liver disease, significant protein deficiency going into surgery, certain untreated mental health conditions, or a history that suggests the post-operative nutritional commitment won't be followed. The pre-surgical evaluation is designed to identify all of this before the operation.

What You'll Need to Do Long-Term

SADI-S requires a lifelong commitment to supplementation and monitoring — more demanding than sleeve or bypass, though less demanding than traditional duodenal switch. You'll need to maintain a high daily protein intake, typically 80–90 grams or more, because the bypass reduces how efficiently your body absorbs protein. Fat-soluble vitamins — A, D, E, and K — need higher supplement doses than after sleeve or bypass. B12, iron, and calcium also require lifelong supplementation, and regular lab work is how we catch deficiencies before they become clinical problems.

Research shows protein malnutrition occurs in 3–8% of SADI-S patients at five years, compared to 15–20% after traditional DS. B12 deficiency appears in 20–40%, iron deficiency in 30–50%, and fat-soluble vitamin deficiencies in 10–25%. These are largely preventable numbers — they reflect patients who aren't supplementing adequately or aren't attending follow-up. Patients who take their supplements and come in for annual labs do well. Patients who stop are the ones who develop problems, often years after surgery when they feel completely fine.

We go through the supplement protocol in detail before surgery. There are no surprises post-operatively for patients who paid attention going in.

What We Tell Patients in Consultation

SADI-S is the procedure Dr. Brown is nationally known for. She is a recognized expert in this operation and a Da Vinci robotic system national proctor — meaning she trains other bariatric surgeons how to perform it. When a patient comes to us needing a duodenal switch-level procedure, SADI-S is her first recommendation in most cases. Experience matters in this procedure more than most, and it's not widely available at this level of expertise.

What we tell every SADI-S candidate is the same: this procedure will produce powerful, lasting results — and it will ask more of you after surgery than sleeve or bypass would. The supplement commitment is real. The follow-up requirement is real. The protein targets are real. Patients who go into surgery understanding and accepting those requirements are the ones who get the most out of what SADI-S can do. Those who treat it casually are the ones who run into trouble years later.

If SADI-S isn't covered by your insurance, we perform the traditional duodenal switch with the same surgical standard and the same post-operative protocols — and we'll have that conversation with you honestly at consultation. You can also review what results to expect from bariatric surgery or compare options on our weight loss surgery overview page.