The primary objective of this study is to determine the effects of ribupatide administered by subcutaneous (SC) injection once weekly compared to placebo on percent change in body weight.

Key Inclusion Criteria:

• BMI ≥35 kilograms per meter squared (kg/m^2).
• History of at least 1 self-reported unsuccessful effort to lose weight with diet and exercise within the prior 6 months.

Key Exclusion Criteria:

• Current diagnosis or history of diabetes mellitus, including type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM), history of diabetic ketoacidosis, or hyperosmolar state/coma.
• Started medications within 3 months prior to Screening that may cause significant weight gain, including, but not limited to, tricyclic antidepressants, atypical antipsychotics, and mood stabilizers.
• Unstable weight defined as self-reported change in body weight exceeding 5% within 3 months prior to Screening.
• Family or personal history of multiple endocrine neoplasia Type 2 or medullary thyroid cancer.
• Uncontrolled hypertension or unstable cardiovascular disease.
• History of chronic or acute pancreatitis.
• Known clinically significant gastric-emptying abnormality or chronic treatment with medications that directly affect gastrointestinal motility.
• History of suicide attempt.
• History of significant active or unstable Major Depressive Disorder (MDD) or other severe psychiatric disorder within 2 years prior to Screening.
• Received treatment with semaglutide, tirzepatide, glucagon-like peptide-1 receptor (GLP-1R) agonist, GLP-1R/glucose-dependent insulinotropic polypeptide receptor (GIPR), or glucagon receptor agonist within 3 months prior to Screening.

Note: Additional inclusion/exclusion criteria may apply, per protocol.