Inclusion Criteria:

• Adults with obesity (BMI >30Kg/m2); these will be otherwise healthy individuals with no unstable psychiatric disease and controlled comorbidities or other diseases.
• Age: 18-75 years old.
• Gender: Men or women. Women of childbearing potential will have negative pregnancy tests within 48 hours of enrolment and before each radiation exposure.
• Participant must have an abnormal phenotype based on testing done in visit 2.

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 the FDA-approved medications: Phentermine-Topiramate Extended Release; Phentermine; ; Oral naltrexone extended-release/bupropion extended-release (NBSR; Contrave®, Mysimba™); and Liraglutide (Saxenda®).
• Participants with >1 phenotype based on the following criteria:
  1. No match to any phenotype based upon 90th and 75th percentile criteria; or
  2. Matches 2 or more phenotype based upon 90th percentile criteria; or
  3. No match to phenotype based on 90th percentile criteria and 2 or more match to phenotype based upon 75th percentile criteria