This is a prospective, pragmatic, 21 month, single-center, randomized, 2-phased, open-label, parallel-group trial comparing the use of enhanced lifestyle changes (ELC) in two different sequential anti obesity medication (AOM) therapies. The ELC consists of a medically-supervised and comprehensive weight loss program (Cleveland Clinic's Department of Endocrinology, Diabetes and Metabolism's Integrated Weight Management Program). In the first phase (9 months) of the study, all participants will receive tirzepatide 15 mg (option #1) or semaglutide 2.4 mg if tirzepatide is not tolerated. In the second phase, after completing 9 months of tirzpeatide or semaglutide, participants will continue ELC and will be randomly assigned to a different oral AOM therapy for another 12 months: group 1 (phentermine-topiramate or naltrexone-bupropion) or group 2 (orlistat). The primary endpoint will be the percentage weight loss at 21 months compared to weight loss at 9 months. The goal will be to show superiority of the arm receiving ELC plus AOM therapy (phentermine-topiramate or naltrexone-bupropion) when compared to the other AOM therapy group (orlistat). Secondary and exploratory endpoints will include percentage of fat mass loss, lean muscle mass, functional capacity, muscle strength and compliance to enhanced lifestyle changes. Informed consent will be obtained. IRB approval of the study will be obtained.