This study will compare different doses of a green fluorescent product that is administered during weight loss surgery in order to observe where blood vessels are located. There is uncertainty around the optimal dose of this product for patients with obesity, so this study will aim to study if the dose in the minimal range recommended by international guidelines is sufficient for most patients or if higher doses are needed with increasing body mass index.

Inclusion Criteria:

• Diagnosis of obesity with a BMI ≥ 30 kg/m²
• Scheduled for revisional bariatric surgery

Exclusion Criteria:

• Allergy to iodides.
• Anticoagulation with products containing sodium bisulfite (due to the risk of ICG-FA inactivation).
• Use of radioactive iodine studies within the past 7 days.
• Pregnant, breastfeeding, or planning to become pregnant within the next year (due to unknown teratogenic or fertility effects of ICG-FA).
• History of liver disease or laboratory findings suggestive of moderate to severe hepatic disease: total bilirubin >1.5 times the upper limit of normal (ULN), or any elevation of aspartate aminotransferase (AST) above ULN.
• Participants who withdraw their consent to participate in the study (elimination criterion).

Anonymized individual participant data will be deposited and made available through an open acess data repository (i.e., Harvard Dataverse). Any potentially sensitive patient-identifying data will either not be released or will undergo minimization and aggregation/abstraction procedures to reduce participant identification risk. Informed consent forms will indicate that a minimal risk of re-identification cannot be excluded despite all these participant data protection methods, in compliance with current IPD sharing recommendations.

IPD and supporting information will be made available with the final original research article, which will be made available as a preprint within a maximum 1-year term after the study conclusion date. This report will be subsequently sent for publication in a peer-reviewed journal. Other pre-specified outcomes may be reported in separate publication after the main research article, reason why the indicated time frame does not apply for such outcomes. There i

No data and supporting information access restrictions are anticipated, as these will be deposited in open access repositories (i.e., Harvard Dataverse, Open Science Framework, Zenodo).

Group assignment is centrally managed. Participants are blinded under anesthesia, with no awareness of group assignment. The anesthesiologist knows the dose but is blinded to outcomes and conceals the dose from surgeons. Data collectors and laboratory technicians are not informed of group assignment or study purpose. Adjudicators of outcomes, not involved in surgery, will assess postoperative videos blinded to patient characteristics and knowing only the timing of drug administration. Data analysts and the data safety monitoring committee use coded identifiers to remain blinded to group assignments. The manuscript's results will be written blinded, after which codes will be replaced for actual doses to interpret and discuss the findings.