Identification of Phenotypic Factors That Predict Success for Weight Loss and Long-term Weight Maintenance

Inclusion Criteria: * Obese males and females: age \>20 years; Obese population defined as BMI \> or = 27 kg/m2 * Lean population BMI \< 27 but \> 17 kg/m2 * Able and willing to provide written informed consent for the trial Exclusion Criteria: * Evidence of inherited disorders of lipid metabolism. * History of Cancer within the last 5 years * Human immunodeficiency virus (HIV) antibody positive. * Patients with solid organ transplants. * Participation in any other clinical trial within 90 days of entry into this trial. * Pregnant or lactating females. * Uncontrolled thyroid disease * Unstable angina or NY heart association class II failure or above * Gastrointestinal disease specifically GI motility disorders * Unstable neuropsychiatric disease including major depression/anxiety, eating disorder such as binge eating, bulimia or anorexia * End stage renal or hepatic disease * Autoimmune disorders (e.g. SLE) * Body weight fluctuation of more than 5 kg in the previous 3 months * Prior bariatric surgery * A history or current alcohol/substance abuse and change in smoking habits or cessation in the past 6 months. * Women of childbearing age must use a reliable form of contraception. * Any medical condition, which in the opinion of the investigator would make the patient unsuitable for recruitment, or could interfere with the patient participating in or completing the protocol. * Unwilling or unable to consent for the study.