The primary objective of this study is to determine the efficacy of oral KAI-7535 once daily compared with placebo on percent change in body weight in participants living with obesity or overweight, with at least 1 weight-related comorbidity, without diabetes mellitus. Efficacy in participants with type 2 diabetes mellitus will be evaluated. Safety and tolerability and other weight-related outcomes will be evaluated in both types of participants.

Key Inclusion Criteria:

• For participants without diabetes mellitus at screening and on Day 1, BMI ≥30 kilograms/square meter (kg/m^2) or BMI ≥27 kg/m^2 and a previous diagnosis of at least 1 of the following:

  • Hypertension
  • Dyslipidemia
  • Obstructive sleep apnea
  • Cardiovascular disease

• For participants living with type 2 diabetes mellitus and BMI ≥27 kg/m^2 only:

  • Diagnosis of type 2 diabetes mellitus
  • On stable therapy for type 2 diabetes mellitus for at least 3 months prior to screening

Key Exclusion Criteria:

• For participants without diabetes:

  • Laboratory evidence of diabetes
  • Taking a concomitant medication for the indication of glycemic control

• For participants living with type 2 diabetes mellitus only:

  • History of diabetic ketoacidosis or hyperosmolar state/coma within 1 year of screening
  • History of severe hypoglycemia or hypoglycemia unawareness within 1 year of screening
  • History of proliferative diabetic retinopathy, diabetic maculopathy, or nonproliferative diabetic retinopathy that required acute treatment

• Started medications that may cause significant weight change within 3 months prior to screening, including 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 carcinoma

• 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 or other severe psychiatric disorder

• Received treatment with semaglutide, tirzepatide, glucagon-like peptide-1 (GLP-1) receptor agonist, GLP-1/glucose-dependent insulinotropic polypeptide receptor agonist, or glucagon receptor agonist within the last 3 months prior to screening

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