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Vol. 2, Issue 17 | November 3, 2026

Five-year bypass versus sleeve evidence meets a changing bariatric practice: fewer dehydration readmissions, falling procedural volume, and different learning curves for robotic teams and surgeons.

Article of the Week

C. Joe Northup, Vance L. Albaugh, Ben Clapp et al. | Surgery for Obesity and Related Diseases, Sep. 25, 2026 | 10.1016/j.soard.2026.09.018

The ASMBS volume assessment found 224,210 procedures in 2022 versus 168,588 in 2024 at 883 continuously reporting MBSAQIP centers, a 24.8% decline. Separately, registry data and a six-state multiplier yielded a 2024 national estimate of 200,667 procedures. The national figure uses a different estimation method than earlier task force reports; the decline reflects following the same centers over time.

The decline accelerated from 6.2% in 2023 to 19.9% in 2024, with implications for program capacity and training exposure. Medication uptake coincided with falling volume, but these observational data cannot establish that drugs caused the contraction. Authors disclosed consulting, speaking, proctoring, or honoraria relationships with drug and device companies and insurers.

KEY FINDING

Procedure volume fell 24.8% across the same 883 centers between 2022 and 2024. That matched-center trend is distinct from the separately modeled national estimate.

A — Metabolic Surgery Research

Saija Hurme, Kari Auranen, Eliisa Löyttyniemi et al. | Obesity Surgery, Oct. 30, 2026 | 10.1007/s11695-026-08993-8

Across four European randomized trials with 975 patients at five years, Roux-en-Y gastric bypass produced greater weight loss than sleeve gastrectomy. The pooled advantage was 3.6 percentage points in total weight loss (95% CI, 2.4–4.9). Excess weight loss favored bypass by 8.5 points (95% CI, 5.4–11.6), with no observed between-study heterogeneity.

The excess-weight-loss result met equivalence within a ±13-point margin but not a ±9-point margin. Thus, statistical superiority and equivalence can coexist when the allowable difference is broad enough. Because the review assessed weight loss alone, this comparison leaves the complications and quality-of-life trade-offs between operations outside its clinical interpretation.

KEY FINDING

Bypass produced 3.6 percentage points more total weight loss at five years. The same result can support superiority and equivalence when the prespecified equivalence margin is sufficiently broad.

Pattharasai Kachornvitaya, Xinlei Zhu, Sergio Bardaro et al. | Surgery for Obesity and Related Diseases, Oct. 23, 2026 | 10.1016/j.soard.2026.10.003

Disclosure: Coauthor Jerry Dang is an MBS Digest editorial board member.

A TriNetX study matched 359 bypass patients to 359 sleeve patients with preexisting gastroparesis. Starting one year after surgery, gastroparesis appeared in records in 17.5% versus 20.3% of patients (OR, 0.83; 95% CI, 0.57–1.21). Recorded nausea and vomiting affected 28.7% versus 30.9%; neither comparison detected a statistically significant difference.

Prokinetic use was 24% after bypass versus 29% after sleeve; dehydration was 8.1% versus 8.4%. Without gastric-emptying tests or validated symptom scores, absent diagnosis codes cannot establish resolution, and nonsignificance does not establish equivalence. Coauthor Matthew Kroh reports an employment relationship with medical-device manufacturer Medtronic.

KEY FINDING

Recorded gastroparesis occurred in 17.5% after bypass versus 20.3% after sleeve. Medication exposure and symptom coding likewise showed no statistically significant separation between procedures.

Emil Maric, Colin Wang, Kristine Kuchta et al. | Surgery, Sep. 10, 2026 | 10.1016/j.surg.2026.110647

Disclosure: Michael Ujiki reports a Boston Scientific advisory role and speaker/consultancy fees from WL Gore, Medtronic and Olympus; the other authors report no conflicts.

An MBSAQIP analysis of 1,456,480 primary bariatric operations tracked 30-day readmissions from 2015 through 2023. Dehydration or acute kidney injury readmissions fell from 1.2% to 0.5% after sleeve and from 1.8% to 0.9% after bypass (both P<0.0001). Overall readmissions occurred in 3.3% of patients, with dehydration or kidney injury accounting for 28.0% of those returns.

Among patients already readmitted, sleeve was associated with higher odds that the reason was dehydration/AKI rather than another cause (OR, 1.32; 95% CI, 1.26–1.38). This conditional comparison does not reverse bypass's higher population readmission rate. Broad registry codes combine fluid depletion, nausea/vomiting, and renal events; the observed decline cannot identify which care changes caused it.

KEY FINDING

Sleeve readmissions for dehydration or kidney injury fell from 1.2% to 0.5%; bypass rates fell from 1.8% to 0.9%. The improvement coexisted with persistent demographic and comorbidity-related risk differences.

B — Science of Obesity Metabolism

Shurui Yang, Zhongyu Huang, Wei Lu et al. | Current Obesity Reports, Sep. 23, 2026 | 10.1007/s13679-026-00763-y

A review finds no uniform dopamine deficit in obesity: receptor signaling varies across brain circuits and peripheral tissues. Human imaging reports lower, higher or unchanged receptor availability, while animal experiments reveal opposing effects on feeding and thermogenesis. Most human evidence is associative, so dopamine changes cannot yet causally explain treatment response.

One human feeding study used a 35%-fat maintenance diet for 5 days, then 6 days of fat restriction that removed 30% of baseline calories. Restriction increased tonic dopamine and preference for foods rich in fat and carbohydrate compared with the maintenance phase. The review also describes dopamine changes after surgery and incretin therapy in relation to eating behavior.

CONTEXT

Dopamine signaling varies across circuits and peripheral tissues. The review favors a context-dependent account of appetite and metabolism over a single reward-deficiency explanation.

Farshad Taherpour, Mahsa Najafi Kandovan, Sepideh Soleymani et al. | Obesity Surgery, Oct. 5, 2026 | 10.1007/s11695-026-08970-1

Disclosure: The review authors declare no competing interests.

Taherpour and colleagues review neutrophil extracellular traps (NETs), DNA-protein structures linking obesity to inflammation and thrombosis. Their narrative synthesis includes clinical and animal studies, with direct human postoperative NET evidence limited to small cohorts. NET markers change with metabolic improvement, but the direction and timing vary by study and assay.

The review's human evidence includes sleeve studies assessed at 3 and 12 months and a gastric-band cohort with 18 completers. One cohort showed heterogeneous postoperative NET changes; another described normalization of impaired in-vitro NET release. These findings support immune remodeling but do not prove that NET suppression reduces cardiovascular events or provides a therapeutic target.

CONTEXT

Small human cohorts show changes in NET markers and neutrophil function after bariatric surgery. Responses vary across assays and procedures; a causal reduction in cardiovascular events through NET suppression remains unproven.

Gordon I. Smith, Max C. Petersen, Sean M. Hartig et al. | Nature Medicine, Oct. 27, 2026 | 10.1038/s41591-026-04718-7

A review describes markedly different metabolic responses to weight loss at similar levels of adiposity. In metabolically unhealthy obesity, losses of 5%, 11% and 16% progressively improved insulin sensitivity; in rigorously defined healthy obesity, 15–25% loss did not improve already-normal insulin action. These contrasting responses separate weight reduction from its metabolic payoff.

Across 60 studies involving 340,636 adults, estimated healthy-obesity prevalence fell from about 50% to 10% as definitions tightened. Inconsistent criteria limit comparisons, and normal metabolic tests do not exclude sleep apnea or musculoskeletal disease. Samuel Klein reports paid advisory roles with AbbVie and Boehringer Ingelheim and investigator-initiated grant support from Merck.

KEY FINDING

Baseline insulin sensitivity distinguishes the metabolic response to weight loss. Similar BMI values can therefore conceal substantially different metabolic treatment benefits.

Claudia K. Fox, Sarah C. Armstrong, Aaron S. Kelly | JAMA, Oct. 21, 2026 | 10.1001/jama.2026.18806

Disclosure: Fox reports institutional research funding from Lilly and Novo Nordisk. Kelly reports research support or donated drugs and unpaid industry consulting, including Novo Nordisk, Lilly, Boehringer Ingelheim and Vivus. Armstrong coauthored the AAP guideline discussed in the review.

A pediatric review reports obesity in 15% of US children aged 2–5 and 22% aged 6–11. Intensive family-based treatment involves at least 26 contact hours over 3–12 months and reduces BMI by 0.7 relative to children who do not receive it. The intervention combines nutrition, activity and behavioral education for children and caregivers, rather than relying on brief counseling alone.

The review describes 82 children aged 6 to <12 randomized to liraglutide 3 mg daily or placebo for 56 weeks: BMI changed by −5.8% versus +1.6% (difference, −7.4 percentage points; 95% CI, −11.6 to −3.2). Gastrointestinal events occurred in 80% versus 54%. These trial results do not establish long-term safety; the review reports US obesity approval at age 12 or older.

KEY FINDING

At least 26 hours of family-based treatment produced a measurable BMI benefit in the reviewed evidence. Medication eligibility varies with age and the underlying cause of obesity.

C — Metabolic Innovation and Technology

Chih-Kun Huang, Larry Weng-Hong Lai, Ming-Che Hsin et al. | Journal of Robotic Surgery, Oct. 3, 2026 | 10.1007/s11701-026-04011-2

Disclosure: The authors report no competing interests and no specific funding.

In 100 consecutive Hugo procedures combining small bowel length shortening with sleeve gastrectomy, team workflow and surgeon performance followed different learning curves. Early versus late median console time fell from 23 to 16 minutes, and total operative time from 95 to 77 minutes. Docking time fell descriptively from 6 to 4 minutes across the same phases.

The docking breakpoint was case 33.1 (95% CI, 26.2–40.0); console time had no stable mid-series transition. Complications occurred in 1/33 early versus 7/67 late cases (P=0.265). The surgeon had performed 64 da Vinci BOS-SG cases, whereas the Hugo team was different. These curves describe platform adaptation after training, not a credentialing threshold for robot-naive surgeons.

KEY FINDING

The docking-time transition occurred around case 33, while console performance improved without a stable mid-series threshold. Team workflow and surgeon performance followed different learning curves.

Harsha Nori, Mayank Daswani, Christopher Kelly et al. | Science, Oct. 22, 2026 | 10.1126/science.aeh7930

A diagnostic AI orchestrator achieved 83.2% accuracy on complex NEJM cases versus 36.1% for participating generalists; emergency-case accuracy was 80.3% versus 46.8%. The benchmark used 304 NEJM and 325 emergency encounters as interactive text cases. Estimated NEJM workup cost was $5,431 for unconstrained AI versus $4,725 for physicians using reference tools.

Budget-constrained AI reached 80.9% NEJM accuracy at $2,241, illustrating a trade-off rather than uniformly cheaper testing. Text simulation does not establish bedside safety or superiority over specialist teams. Microsoft funded the work; all authors were employees and shareholders, and several held a related patent application, making independent clinical validation consequential.

KEY FINDING

Accuracy reached 83.2% for unconstrained AI versus 36.1% for participating generalists on complex text cases. Budget constraints reduced estimated workup cost while retaining 80.9% accuracy.

HM Treasury | UK Government / HM Treasury, Oct. 28, 2026 | Source ↗

The UK Budget commits £100 million to robotic-assisted surgery in England, supporting an intended rise from 70,000 procedures annually to 500,000 by 2035. A national robotics registry will use data and AI to track and improve care. The investment links equipment expansion to routine collection of outcomes across the wider surgical service, rather than a bariatric-specific program.

A separate £190 million allocation supports NHS winter pressures in 2026–27, alongside 25 new or expanded urgent care sites. The robotics program links wider access with expectations of greater efficiency and fewer geographic and gender inequalities. Its value will depend on outcomes and delivery costs, because rising procedure counts alone cannot demonstrate better care.

CONTEXT

£100 million supports robotic surgery expansion in England, paired with a planned national registry. The 500,000-procedure annual goal for 2035 describes intended capacity rather than achieved activity.

D — Metabolic Marketplace

Ascletis Pharma Inc. | Ascletis corporate release via PR Newswire, Oct. 26, 2026 | Source ↗

Ascletis submitted an FDA investigational new drug application for oral ASC39 and anticipated a Phase I trial in late 2026. In its receptor assay, amylin EC50 was 21.4 pM for ASC39 versus 21.2 pM for eloralintide; selectivity over the calcitonin receptor was 40-fold versus 64-fold. These laboratory comparisons describe receptor activity, not comparative weight loss in patients.

The company reported 6.6% placebo-adjusted weight loss in obese rats given oral ASC39 at 5 mg/kg daily for six days. Human efficacy and tolerability remain unestablished, and an IND submission is neither FDA approval nor confirmation that a trial may begin. The proposed oral amylin approach broadens the development pipeline beyond incretins, but its clinical role is unresolved.

CONTEXT

ASC39 produced 6.6% placebo-adjusted weight loss over six days in obese rats at 5 mg/kg daily, according to Ascletis. The company anticipates a Phase I trial of its oral amylin candidate.

American Society for Metabolic and Bariatric Surgery | ASMBS announcement provided by the editor, undated | ASMBS public confirmation (Oct. 30, 2026)

ASMBS named John Morton and Tammy Kindel co-editors-in-chief of Surgery for Obesity and Related Diseases. They will work under Raul Rosenthal as he transitions out of the role by June 30, 2027. Morton brings surgical quality leadership at Yale and experience as ASMBS president in 2014–15; Kindel leads surgical research at the Medical College of Wisconsin.

Morton has authored more than 250 publications, while Kindel has more than 100 and joined SOARD as associate editor in 2024. Their backgrounds span quality measurement and mechanistic research, including Kindel's work on cardiac improvement after metabolic surgery. The appointment outlines a leadership handover, but does not specify changes to peer review or editorial policy.

CONTEXT

John Morton and Tammy Kindel will co-lead SOARD. The announced transition retains Raul Rosenthal’s guidance ahead of his departure on or before June 30, 2027.

Eli Lilly and Company | Eli Lilly and Company investor relations, Oct. 29, 2026 | Source ↗

Eli Lilly reported third-quarter revenue of $24.397 billion versus $17.601 billion a year earlier, a 39% increase. Worldwide volume rose 53%, while realized prices fell 15%, with Mounjaro and Zepbound leading demand. Mounjaro revenue reached $10.723 billion versus $6.515 billion; Zepbound reached $5.352 billion versus $3.588 billion, separating sales growth from higher pricing.

Lilly raised its annual revenue outlook to $91–92 billion from $85–87 billion, although the quarter included about $900 million in milestone and rebate-related benefits. These company financial results describe demand and pricing, not comparative clinical effectiveness. Lower realized prices also do not establish lower out-of-pocket costs or sustained access for individual patients.

CONTEXT

Lilly reported 53% volume growth alongside a 15% decline in realized prices. Mounjaro and Zepbound revenue both increased as demand outweighed pricing pressure.

Closing the gaps in knowledge...

Production Editor John D. Scott MD FACS | [email protected]

This issue's ballot: 9 of 11 board seats voted.
MBS Digest | November 3, 2026 | Vol. 2, Issue 17
For educational purposes only.