Bariatric surgery has come a long way in the past few decades. What started as simple, malabsorptive procedures has evolved into safer, advanced operations that alter how the body processes and absorbs food by modifying the digestive tract. One of the most exciting developments is the emergence of newer hypoabsorptive (ileal) surgeries, such as SASI, which aim to achieve sustainable weight control and improve metabolic health.
While older versions often led to serious nutrient deficiencies, innovative techniques aim to deliver the same weight loss results with fewer long-term risks. In this blog, we’ll break down the latest hypoabsorptive procedures and see how they stack up against traditional bariatric surgery.
Understanding Hypoabsorptive Surgery
Hypoabsorptive surgery functions by rerouting the Gastrointestinal (GI) tract to bypass a significant portion of the small bowel (sowel) where most nutrient absorption takes place. These novel procedures are often called “ileal metabolic surgeries” because they specifically engage the ileum (the final section of the small intestine).
By combining restrictive and bypass mechanisms, these procedures match or surpass the results of more common RYGB and SG surgeries, particularly in patients with a BMI over 50 kg/m² [1]
Procedures, such as the classical Duodenal Switch (BPD/DS) and its variants — SASi-S, SADi-S, SAGi-S, TBSi-S, and MagDI — are a prime example of this approach, designed to alter metabolic function. They work by transitioning food from the stomach to the distal ileum, which promotes the immediate secretion of satiety hormones, such as GLP−1 and PYY-36. These newer procedures are showing promising results.
Hypoabsorptive Procedures Options
A key distinction among various ileal surgeries is where and how the connection, “anastomosis,” is made, and the number of them. SASI, SADI, SAGil, and MagDI procedures use only one anastomosis, as opposed to two in the conventional DS/BPD and TBSI.
Procedures with fewer intestinal anastomoses (unions) are less surgically complex and carry a lower risk of serious complications, such as leaks or strictures.
Key Differences Between Popular Ileal Surgeries:
The newer variations of traditional DS/BPD that include only one connection (anastomosis) are showing promising results.
SADI-S Surgery
- Single Anastomosis Duodeno–ileal Bypass with Sleeve Gastrectomy (SADI-S)+, also known as SIPS, is an offspring of traditional BPD/DS surgery characterized by a single anastomosis. The total length of the small intestines varies from patient to patient, averaging about 6 meters or 20 feet long.
SASI-S Surgery
- Single Anastomosis Stomach–ileal with Sleeve Gastrectomy (SASI-S) is a newer iteration of classic ileal surgery that utilizes a single union connecting the lower part of the stomach to the ileum.
Key Stat: SASI-S has shown remarkable results in improving type 2 diabetes. On average, patients achieve 70–80% remission from diabetes. In a study of 61 patients, the remission rate for type 2 diabetes was 72% just one year after SASI-S.[2] - Single Anastomosis Gastro-Ileal with Sleeve Gastrectomy (SAGi-S) is very similar to SADI, with a main difference. Instead of connecting the duodenum (first part of the small intestine) to the ileum, SAGI connects the lower portion of the stomach (usually near the antrum) directly to the lower part of the intestine (the ileum).
- Transit Bipartition Sleeve-Ileal with Sleeve Gastrectomy (TBSi-S) is similar to SASI, with one difference. There are two anastomoses made instead of one.
- Ileo-Transverse Colon Bypass connects the ileum to the transverse colon, bypassing a section of the large intestine. It is performed to treat obstructive right-sided colon cancer or for other select injuries to the colon.
- Magnetic Duodeno-Ileostomy (MagDI) is a pioneering minimally invasive weight loss surgery that was FDA-cleared in October 2024. The MagDI procedure utilizes self-aligning magnets to establish a natural connection between the duodenum and ileum, eliminating the need for cutting or stapling. Typically done after sleeve gastrectomy, it can be integrated into duodenal switch variations and offers a lower-risk option with faster recovery, fewer complications, and more normal intestinal flow.
Key Stat: In clinical studies, no Magnet System-related complications were observed, with 0% incidence of anastomotic leakage, bleeding, or infection.[3]
| Duodenal Switch Variations | Restriction | Malabsorption | Anastomoses | Nutrient Deficiency | Excess Weight Loss | Diabetes Remission | Complication Risk | Recovery (weeks) | Operation Complexity | Surgery Duration (min) |
|---|---|---|---|---|---|---|---|---|---|---|
| SASI-S | Yes | Moderate | 1 | Moderate | 88% | ~70-80% | Low | 2 | Simple | 120 |
| SADI-S | Yes | Moderate-High | 1 | Moderate-High | 90% | ~80-90% | Moderate | 2-3 | Moderate | 150 |
| SAGI-S | Yes | Moderate-High | 1 | Moderate | 89% | ~70-80% | Low | 1-2 | Simple | 150 |
| TBSI-S | Yes | Moderate | 2 | Moderate | 88% | ~85-95% | High | 3-4 | Difficult | 140 |
| MagDI | Yes | Moderate | 1 | Low | 89% | ~60-70% | Low | 1-2 | Very Simple | 120 |
Pros and Cons of Ileal Surgeries
Although gastric sleeve and bypass operations are effective, ileal surgeries offer the distinct advantages of more durable weight control and greater improvement in conditions like type 2 diabetes and high blood pressure.
Pros:
- Significant Weight Loss – Longer-lasting than restrictive procedures.
- Metabolic Benefits – Can improve or reverse diabetes, hypertension, and cholesterol; boosts insulin sensitivity.
- Effective for Severe Obesity – Ideal for higher BMIs or those who struggled with restrictive surgeries.
- Improved Quality of Life – Increases energy, mobility, and reduces joint pain
Cons:
- Nutrient Deficiencies – Risk of vitamin and mineral deficiencies; requires lifelong supplements and monitoring.
- Digestive Side Effects – May cause diarrhea, bloating, or food intolerances.
- Surgical Complexity – Longer surgery than restrictive procedures.
- Revision – In the event that weight returns, it is harder to revise.
Am I a Candidate?
If you’re looking for a bariatric option that can deliver more dramatic and lasting results, an ileal surgery might be the right choice. Candidacy is typically determined by:
- A Body Mass Index (BMI) of 45 or higher.
- A BMI of 40 or higher with significant obesity-related health conditions, such as type 2 diabetes, hypertension, or sleep apnea.
The best way to know for sure is to consult with our qualified bariatric surgeons.
The Future of Hypoabsorptive Surgery
Ileal metabolic procedures are among the most powerful tools available in the fight against severe obesity. With innovations like single-anastomosis techniques and magnet-assisted technology, they are now safer and more accessible than ever.
Mexico Bariatric Center® (MBC) has been at the forefront of bariatric surgery and is offering ileal procedures, including SASI, SADI, and BiPartition.
If you’re considering your weight loss options, consult with MBC’s qualified surgeons about the full range of procedures to find the one that best matches your health and lifestyle goals.
Sources:
1. Abedalqader T, Jawhar N, Gajjar A, Portela R, Perrotta G, El Ghazal N, Laplante SJ, Ghanem OM. Hypoabsorption in Bariatric Surgery: Is the Benefit Worth the Risk? Medicina (Kaunas). 2025 Feb 25;61(3):398. doi: 10.3390/medicina61030398. PMID: 40142209; PMCID: PMC11944201.
2. Mousavi Naeini SM, Toghraee MM, Malekpour Alamdari N. Safety and Efficacy of Single Anastomosis Sleeve Ileal (SASI) Bypass Surgery on Obese Patients with Type II Diabetes Mellitus during a One-Year Follow-up Period: A Single Center Cohort Study. Arch Iran Med. 2023 Jul 1;26(7):365-369. doi: 10.34172/aim.2023.55. PMID: 38301094; PMCID: PMC10685819.
3. Gagner, M., Almutlaq, L., Cadiere, G.-B., Torres, A. J., Sanchez-Pernaute, A., Buchwald, J. N., & Abuladze, D. (2024). Side-to-side magnetic duodeno-ileostomy in adults with severe obesity with or without type 2 diabetes: Early outcomes with prior or concurrent sleeve gastrectomy. Surgery for Obesity and Related Diseases, 20(4), 341–352. https://doi.org/10.1016/j.soard.2023.10.018
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