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.