The goal of this clinical trial is to learn which dose of study drug IBIO-600 has the right balance of safety, tolerability and impact on body composition in overweight and obese adult participants.

The study is a single ascending dose study, with participants monitored for 9 months after administration.

This clinical trial will seek to address the following:

• Which dose of the study drug is most effective.
• How safe the study drug is and how well participants tolerate it.
• How much of the study drug can be found in blood (pharmacokinetics).
• How the study drug affects the body (pharmacodynamics).
• How the body's immune system responds to the study drug (immunogenicity).
• How the body's composition and physical function may change over the course of the study.

Inclusion Criteria:

• Aged 18 to 65 years of age
• In good general health, with no significant medical history
• BMI between ≥ 27.0 and ≤ 34.90 kg/m2
• History of self-reported stable body weight (defined as change of no more or less than ± 5%) within 90 days of Screening.
• Willingness to refrain from any reconstructive and/or cosmetic surgery and/or non-invasive cosmetic procedure that may affect body weight during the study
• Must be fully ambulatory without any chronic orthopedic diseases or reliance on crutches, walkers, or a wheelchair that may preclude normal activity.
• Be a nonsmoker/nonvaper and must not have used any nicotine or synthetic type products within 1 month prior to randomization.
• Must not be pregnant or breastfeeding
• Woman of childbearing potential (WOCBP) or fertile man agrees to use an acceptable method of contraception from the start of Screening until study completion, or for a minimum of 9 months following the last dose of IP, whichever period is longer.

Exclusion Criteria:

• An underlying physical or psychological medical conditions that, in the opinion of the PI or medical designee, would make the participant unlikely to comply with the protocol or complete the study per protocol.
• History or active diagnosis of diabetes (Type 1 or 2).
• History of insulinoma or recurrent hypoglycemia (≥ 3 episodes in past 3 months).
• History or presence of clinically significant muscle disease
• History of or active cardiovascular disease including clinically significant arrhythmias, Class I-IV heart failure, coronary artery disease, thromboembolic event, or pulmonary hypertension.
• Clinically significant laboratory abnormalities that would preclude participation in the study.
• History of malignancy, except for non-melanoma skin cancer excised > 2 years ago or cervical intraepithelial neoplasia successfully treated > 5 years prior to randomization.
• History or presence of any condition associated with significant immunosuppression.
• History of substance abuse or dependency, or recreational IV drug use within the past 5 years (self-reported).