The purpose of this study is to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of HRS-5817 when administered subcutaneously (SC) as single and multiple doses in adults who are affected by obesity.

Inclusion Criteria:

1. Voluntarily sign the informed consent form prior to any study-related activities, understand the procedures and methods of the study, and agree to complete this study in strict accordance with the clinical study protocol.
2. Males or females aged 18-55 years old (inclusive).
3. Subjects who are generally healthy as judged by the investigator based on medical history, vital signs, physical examination, laboratory tests and electrocardiogram (ECG) results.
4. Body weight change (difference between the maximum body weight and the minimum body weight within 3 months) of no more than 5 kg within the past 3 months.
5. Female subjects of childbearing potential must agree to take highly effective contraceptive measures and avoid egg donation from the signing of the informed consent form to 6 months after the last dose, and must have a negative blood pregnancy test result before administration and not be breastfeeding. Male subjects whose partners are women of childbearing potential must agree to take highly effective contraceptive measures and avoid sperm donation from the signing of the informed consent form to 6 months after the last dose.

Exclusion Criteria:

1. Known or suspected allergy to any ingredient in the investigational medicinal products or related products; or history of multiple and/or severe allergies to drugs or food, or history of severe anaphylaxis.
2. History of or suffering from major diseases of cardiovascular, endocrine (except primary obesity), mental, neurological, digestive, respiratory, blood, immune or genitourinary systems, which are not suitable for participation in this study as judged by the investigator.
3. Subjects who have had severe trauma or undergone major surgical procedures within 6 months before screening, or who plan to undergo surgery during the study.
4. Subjects who have participated in and used any other clinical trial drugs or medical device treatments within 3 months prior to screening or plan to do so during the study period, or within 5 half-lives of the investigational drug before screening (whichever is longer).
5. Significant changes in diet and exercise habits within 1 month before screening, or failure to maintain a basically stable lifestyle such as diet and exercise during the study.
6. Known or suspected history of drug abuse or substance abuse, or positive urine drug screening during the screening period.
7. Other situations that may interfere with the evaluation of the study results or are not suitable for participating in this study as judged by the investigator.