ObjectiveThe objective of this study was to describe the rationale and design of two multinational phase 3 clinical trials of survodutide, an investigational glucagon and glucagon‐like peptide‐1 receptor dual agonist for the treatment of obesity with or without type 2 diabetes (T2D; SYNCHRONIZE‐1 and ‐2).MethodsIn these ongoing double‐blind trials, participants were randomized to once‐weekly subcutaneous injections of survodutide or placebo added to lifestyle modification. Survodutide doses are uptitrated to 3.6 or 6.0 mg, and dose flexibility is permitted. Participants (n = 726) in SYNCHRONIZE‐1 (NCT06066515) have a baseline BMI ≥ 30 kg/m2 or ≥27 kg/m2 with at least one obesity‐related complication but without T2D; participants (n = 755) in SYNCHRONIZE‐2 (NCT06066528) have a baseline BMI ≥ 27 kg/m2 and T2D. The primary endpoints are percentage change in body weight and proportion of participants achieving ≥5% body weight reduction from baseline to week 76. Secondary endpoints include change in systolic blood pressure and measures of glycemia. A SYNCHRONIZE‐1 substudy is evaluating changes in body composition and liver fat content using magnetic resonance imaging.ConclusionsThese trials are designed to provide robust evaluation of the efficacy, safety, and tolerability of survodutide for the treatment of obesity in the presence or absence of T2D.