The main purpose of this study is to determine if retatrutide can significantly lower the incidence of serious heart-related complications or prevent the worsening of kidney function. The trial will enroll adults with body mass index 27 kg/m\^2 or higher and Atherosclerotic Cardiovascular Disease and/or chronic kidney disease. The study will last for about 5 years. Participants will have up to 27 clinic visits with the study doctor.