IBI3042 Study in Healthy Participants and Overweight or Obese Participants

Inclusion Criteria: * Aged 18 to 55 years, inclusive. * For Part A: BMI ≥20 and \<30 kg/m\^2 and body weight ≥50 kg. * For Part B: BMI ≥24 and ≤40 kg/m\^2, with stable body weight during the 3 months prior to screening. * Female participants of childbearing potential and male participants with female partners of childbearing potential must agree to use highly effective contraception during the study and for 90 days after the last dose. * Able and willing to comply with study procedures and voluntarily provide written informed consent. Exclusion Criteria: * Known or suspected hypersensitivity to any component of the study drug or to GLP-1 receptor agonists. * History of diabetes or abnormal glycemic parameters at screening. * Personal or family history of thyroid C-cell carcinoma or multiple endocrine neoplasia syndrome type 2 (MEN 2A or 2B), or calcitonin ≥20 ng/L at screening. * History of acute or chronic pancreatitis, or clinically significant pancreatic enzyme elevation at screening. * Use of medications that may significantly affect gastrointestinal motility, appetite, or drug absorption within 3 months prior to screening. * Clinically significant hematologic, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, or neurologic disease that may increase study-related risk or interfere with study assessments. * Clinically significant abnormalities in physical examination or laboratory tests at screening. * History of malignancy within 5 years, except for basal cell or squamous cell skin cancer. * Use of prescription or over-the-counter medications, dietary supplements, or herbal medicines within 2 weeks or 5 half-lives prior to screening, except as permitted by the protocol. * Participation in another drug or medical device clinical study within 3 months prior to screening or within 5 half-lives of the investigational drug, as applicable. * Any other condition that, in the investigator's opinion, makes the participant unsuitable for participation in the study.