First-in-human Study of the Safety, Tolerability, Pharmacokinetics, and Food Effect of ACCG-2671

Inclusion Criteria: * Signed informed consent * Men and women with the following at the time of Screening for Part 1 and 2: ≥25 years and ≤65 years of age and BMI ≥18.0 kg/m2 and \<30.0 kg/m2 * For Part 3, ≥25 years and ≤75 years of age and BMI ≥30.0 kg/m2 * For Part 3, receiving a stable dose of an injectable GLP-1RA for ≥3 months, who responded to GLP1RA treatment with stable body weight and no ongoing GLP-1RA-related symptoms or AEs. For the duration of the study, participants must not be planning to change GLP-1RA dose or discontinue GLP-1RA treatment * Body weight ≥50.0 kg at time of screening Exclusion Criteria: * For Parts 1 and Part 2: Participants with any clinically significant medical conditions are excluded from the study. * For Parts 1, 2 and 3: participants will be excluded from this study if there is evidence of ANY of the exclusion criteria at the Screening Visit or prior to first dose administration * History or presence of significant CV, pulmonary, hepatic, renal, hematological, GI, endocrine, immunologic, dermatologic, psychiatric, or neurological disease, including any acute illness or major surgery within the past 3 months, or any clinical laboratory abnormality determined by the Investigator to be clinically significant * Use of any prescription or over-the counter-medication including herbal products, diet aids, vitamins, or hormone supplements (including contraceptives) within 10 days or 5 times the apparent elimination half-life of the medication (whichever is longer) before the first study drug administration and throughout the study. Exceptions include injectable GLP-1RA treatment for Part 3, Cohort 2c only and medications used to manage AEs at the discretion of an investigator after consultation with the Sponsor.