A Study of LY4329090 in Participants With Obesity or Overweight Who Are Otherwise Healthy

Inclusion Criteria

• Participant must be 18 (21 for Singapore site) to 65 years of age, inclusive, at the time of signing the informed consent.
• Are overtly healthy with no comorbidities related to body mass index (BMI).
• Have a BMI between 27.0 kilograms per square meter (kg/m²) and 40.0 kg/m², inclusive.
• Have had a self-reported stable weight for 3 months prior to screening.

Exclusion Criteria

• Have a history or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal (GI), endocrine, hematological, or neurological disorders.
• Have a history of chronic medical conditions involving the heart, liver, or kidneys.
• Have either

• ongoing asymptomatic bradycardia defined as less than 50 beats per minute at screening visit
• electrocardiogram (ECG) findings at screening visit of second-degree atrioventricular block or higher, or
• history of symptomatic bradycardia with uncorrected etiology, including diagnosis of sick sinus syndrome.
• Have an abnormal blood pressure and/or pulse rate at screening.
• Have an obesity induced by other endocrinologic disorders or diagnosed monogenetic or syndromic forms of obesity.
• Have any of the following:

• a diagnosis of hypocalcemia or hypercalcemia, or
• confirmed abnormal laboratory values for calcium and serum phosphorus.
• Have a known, clinically significant gastric emptying abnormality, have undergone weight loss surgery, or have had endoscopic and/or device-based therapy for obesity or have had device removal within the last 6 months.
• Have been diagnosed with type 1 or type 2 diabetes mellitus or have glycated hemoglobin A1c (HbA1c) greater than or equal to (≥) 6.5 percent (%) or 48 millimoles per mole (mmol/mol) at screening.
• Have a history or presence of psychiatric disorders, within the last 2 years, that would present a safety risk or may significantly impair the participant's ability to comply with study procedures.
• Have taken any glucose-lowering medications, including insulin, in the past 3 months before screening.
• Have received any drugs from the incretins class within 90 days prior to screening.
• Have been treated within 3 months prior to screening or plan to be treated with prescription medications that promote weight loss.
• Intend to use any weight loss medications during study participation.
• Prior (within 6 months) or planned (during the study) device-based treatment use for obesity.