Pilot Study of the Effect of Liraglutide on Weight Loss and Gastric Functions in Obesity

Inclusion Criteria: * Overweight and obese adults (≥30 kg/m\^2 or ≥27 kg/m\^2 with an obesity-related co-morbidity). * Subjects residing within 125 miles of Mayo Clinic in Rochester, Minnesota. * Healthy individuals with no unstable psychiatric disease and not currently on treatment for cardiac, pulmonary, gastrointestinal, hepatic, renal, hematological, neurological, or endocrine (other than hyperglycemia type 2 diabetes mellitus on metformin) disorders. * Women of childbearing potential will be using an effective form of contraception, and have negative pregnancy tests within 48 hours of enrolment and before each radiation exposure. * Subjects must have the ability to provide informed consent before any trial-related activities. Exclusion criteria: * Weight exceeding 137 kilograms (safety limit of camera for measuring gastric volumes). * Abdominal surgery other than appendectomy, Caesarian section or tubal ligation. * Positive history of chronic gastrointestinal diseases, systemic disease that could affect gastrointestinal motility, or use of medications that may alter gastrointestinal motility, appetite or absorption, e.g., orlistat. * Patients with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia-type 2. * Patients with a personal history of pancreatitis (acute or chronic) * Significant untreated psychiatric dysfunction based upon screening with the Hospital Anxiety and Depression Inventory, a self-administered alcoholism screening test (AUDIT-C), and the Questionnaire on Eating and Weight Patterns (binge eating disorders and bulimia). If such a dysfunction is identified by a Hospital Anxiety Depression (HAD) score \>8 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. * Intake of medication, whether prescribed or over the counter (except multivitamins), within 7 days of the study. Exceptions are birth control pill, estrogen replacement therapy, thyroxin replacement therapy and any medication administered for co-morbidities as long as they do not alter gastrointestinal motility including gastric emptying (GE) and gastric accommodation. For example, statins for hyperlipidemia, diuretics, β-adrenergic blockers,Angiotensin Converting Enzyme (ACE) inhibitors and angiotensin antagonists for hypertension, and metformin for type 2 diabetes mellitus or prediabetes are permissible. In contrast, resin sequestrants for hyperlipidemia \[which may reduce GE and reduce appetite, α2-adrenergic agonists for hypertension, or other glucagon-like peptide-1 receptor agonists (GLP-1) receptor agonists (exenatide) or amylin analogs (pramlintide) are not permissible because they significantly affect GE and/or gastric accommodation. * Hypersensitivity to the study medication, liraglutide.