This is a 56-week randomized, open-label, controlled study evaluating the efficacy and safety of the HDM1005 compared to tirzepatide in adults with obesity but without diabetes. Eligible participants will be screened and randomized to different dose group of HDM1005 or the tirzepatide group at a ratio of 1:1:1 :1, HDM1005 or tirzepatide will be given once weekly for 52 weeks, following by a safety follow up of 4 weeks. All participants received a lifestyle intervention that involved counselling on diet and physical activity.

Inclusion Criteria:

1. The age of signing ICF was from 18 to 65 years old (including both ends), regardless of gender.
2. BMI ≥28.0 but <40.0 kg/m2 at screening and randomization
3. Participants reported that they had been under diet and exercise control for 3 months or more before screening, and their weight change (the difference between the maximum body weight and the minimum body weight) in the past 3 months was less than 5%.
4. fertile female subjects who have taken and agreed to continue to take effective contraceptive measures from 14 days before signing ICF to 60 days after the last dose, and have no plans to give birth and donate eggs; Male subjects signed ICF until 90 days after the last dose, had no fertility plan and sperm donation plan, and agreed to use highly effective contraception.

Exclusion Criteria:

1. Previous diagnosis of type 1, type 2, or any other type of diabetes.

2. History or family history of medullary thyroid carcinoma, C cell hyperplasia, or multiple endocrine neoplasia type

3. According to the investigator's judgment, the subjects have endocrine diseases or histories that affect gastric emptying, may significantly affect body weight, or diseases or conditions that affect the absorption of gastrointestinal nutrients, such as Cushing syndrome, hypothyroidism or hyperthyroidism, bariatric surgery or other gastrectomy, irritable bowel syndrome, dyspepsia, and chronic pancreatitis; Or a history of acute pancreatitis or acute gallbladder disease within 3 months before signing ICF.

4. Hypertension that was not stably controlled at screening: systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg (with stable treatment for at least 30 days if antihypertensive medications were used).

   Have any malignant tumor within 5 years before signing ICF (except basal cell carcinoma which has received curative treatment and is regarded as cured).

5. Those who had severe infection, severe trauma, or large or medium-sized surgery within 3 months before signing ICF, or planned to undergo surgery during the study (except outpatient surgery).

6. Previous or combined presence or suspicion of depression or other psychiatric disorders or screening PHQ-9 score ≥15.

7. Known intolerance or allergy to any component of the study drug or glucagon-like peptide-1 receptor (GLP-1R) agonist, or a previous history of severe drug allergy.

8. Use of any of the following drugs, products, or treatments within 3 months prior to signing the ICF, including but not limited to:

   A. a drug, product or treatment with weight loss effect b. Medications, products, or treatments that significantly increase body weight

9. Use of hypoglycemic drugs within 3 months before signing ICF.

10. Have participated in any clinical trial within 3 months before signing ICF or within 5 half-lives (whichever is longer) after the last dose of the investigational drug used in the clinical trial (except for those who signed ICF without drug or device intervention).

11. History of addictive drug abuse within 1 year before signing ICF.

12. Estimated glomerular filtration rate (eGFR) according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation <60 mL/min/1.73 m2;

13. Those who donated blood or lost ≥400 mL of total blood within 3 months before signing ICF, or received blood transfusion or used blood products, or planned to donate blood during the study period.

14. Pregnant or lactating women.