The researchers are trying to identify the specific characteristics (phenotypes) that may be useful to help select the right medication for weight loss.

All participants will be phenotype and participants will randomized to randomly assigned medications vs phenotype guided medications for obesity. All participants will receive a standard intense lifestyle intervention.All participants will be seen at 4 and 12 weeks. At the 12-week visit, participants will be unblinded to their "obesity-related phenotype" and they could contact their physician to continue a FDA-approved medication as part of clinical care. Study team will prospectively follow the patients' weight, waist circumference and use of obesity medications every 3 months for 1 year.

Inclusion criteria:

• Adults with obesity (BMI >30 Kg/m2); these will be otherwise healthy individuals with no unstable psychiatric disease and controlled comorbidities or other diseases.
• Gender: Men or women. Women of childbearing potential will have negative pregnancy tests within 48 hours of enrollment and before each radiation exposure.

Exclusion criteria

• Abdominal bariatric surgery
• Positive history of chronic gastrointestinal diseases, or systemic disease that could affect gastrointestinal motility, or use of medications that may alter gastrointestinal motility, appetite or absorption, e.g., orlistat, within the last 6 months.
• Significant untreated psychiatric dysfunction based upon screening with the Hospital Anxiety and Depression Inventory (HAD), and the Questionnaire on Eating and Weight Patterns (binge eating disorders and bulimia). If such a dysfunction is identified by an anxiety or depression score >11 or difficulties with substance or eating disorders, the participant will be excluded and given a referral letter to his/her primary care doctor for further appraisal and follow-up.
• Hypersensitivity to any of the study medications.
• No contraindications to all FDA-approved medications

Baseline to 12 months