The main purpose of this study is to evaluate the efficacy and safety of retatrutide compared to tirzepatide in adults who have obesity. The study will last about 89 weeks.

Inclusion Criteria:

• Have obesity and a history of at least one self-reported unsuccessful dietary effort to reduce body weight.

Exclusion Criteria:

• Have a self-reported change in body weight >5 kilograms (kg) (11 pounds) within 90 days before screening.

• Have a prior or planned surgical treatment for obesity.

• Have a prior or planned endoscopic procedure and/or device-based therapy for obesity.

• Have taken weight loss drugs, including over-the-counter medications, within 90 days prior to screening.

• Have a family or personal history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN-2).

• Have had within the past 90 days before screening:

  • acute myocardial infarction
  • cerebrovascular accident (stroke)
  • coronary revascularization
  • hospitalization for unstable angina, or
  • hospitalization due to congestive heart failure.

• Have New York Heart Association Functional Classification Class IV congestive heart failure.

• Have a history of chronic or acute pancreatitis.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and EU, whichever is later. Data will be indefinitely available for requesting.

A research proposal must be approved by an independent review panel and researchers must sign a data sharing agreement.