A Study of LY4064912 in Healthy Participants and With Overweight or Obesity

The purpose of this study is to evaluate how well LY4064912 is tolerated and what side effects may occur in healthy participants and participants with overweight and obesity - global. The study drug will be administered either subcutaneously (SC) (under the skin) or infusion intravenously (IV) (into a vein in the arm). Blood tests will be performed to investigate how the body processes the study drug and how the study drug affects the body.

Inclusion Criteria: * Age is 21-65 years old at Singapore Sites * Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, and cardiac monitoring Part A: Body Mass Index (BMI) within the range greater than or equal to 21 and less than 30 kilogram per square meter (kg/m²) Part B: a BMI greater than or equal to 27 and less than 45 kg/m² Part C: a BMI greater than or equal to 21 and less than 35 kg/m² * Parts A and C: Participants must weigh 60 kilograms (kg) or more at screening * Have had a less than 5% change in body weight for 3 months before screening * Safety laboratory tests are within normal reference range Exclusion Criteria: * Have a history or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, or neurological disorders capable of significantly altering the absorption, metabolism, or elimination of drugs; of constituting a risk when taking the investigational product; or of interfering with the interpretation of data * Have history of diabetes (except gestational diabetes) or current diagnosis of diabetes (any form), or have HbA1c greater than or equal to 6.5% (48 millimole per mole (mmol/mol)) at screening * Are individuals of childbearing potential (IOCBP).