Inclusion Criteria:
Obese: BMI\> 30 kg/m2 or \>27 kg/m2 with comorbidities (including but not limited to insulin resistance, hypertension, dyslipidemia, cardiovascular disease, stroke, sleep apnea, gallbladder disease, hyperuricemia and gout, and osteoarthritis).
Additionally, women participants must use double barrier methods to prevent pregnancy (diaphragm with intravaginal spermicide, cervical cap, male or female condom with spermicide). If a woman suspects that she has become pregnant at any time or does not use one of the contraceptive methods recommended by the investigator, she must notify the study staff. If a woman becomes pregnant, she will be withdrawn from the study. The study staff will follow the progress of her pregnancy and the birth of her child.
Exclusion Criteria:
1. Subjects using any other weight loss products (orlistat, phentermine, topiramate, fenfluramine, dexfenfluramine, amphetamines, GLP-1 agonists) or use within 3 months.
2. Women who are breastfeeding, pregnant, or wanting to become pregnant.
3. Women using IUD (intrauterine device)
4. Any change in the dosage of hormonal contraceptive medications (birth control pills, implanon). Subjects should remain on same medication/ same dose during the time of the entire study.
5. Moderate (creatinine clearance of 30-59 ml/min) and severe renal impairment (creatinine clearance below 30 ml/min) and end-stage renal disease
6. Moderate, or severe hepatic impairment
7. Hypersensitivity to the active substance or any of the excipients in lorcaserin
8. Congestive heart failure and/or pulmonary hypertension
9. Arrhythmias (bradycardia, tachycardia) and valvular heart diseases
10. Diagnosis of diabetes, defined per ADA criteria as Hba1c \> 6.5% and/or fasting glucose \> 125 mg/dL and/or random glucose \> 200 mg/dL
11. Inflammatory conditions like inflammatory bowel disease, Rheumatoid arthritis etc.
12. Alcohol consumption- the maximum quantity for men is 140g-210g per week. For women, the range is 84g-140g per week or drinking as consuming no more than two drinks a day for men and one for women. Alcohol can cause increased risk of pancreatitis and hypoglycemia.
13. Untreated thyroid disease like hypothyroidism or hyperthyroidism
14. Subjects taking the following medications: phosphodiesterase inhibitors, serotonergic medications (e.g. SSRI (selective serotonin reuptake inhibitor), SNRI, MAO (monoamine oxidase) inhibitors, bupropion, tricyclic antidepressants, St. John's Wort), valproic acid, codeine (CYP2D6 inhibition), tamoxifen, timolol, warfarin, steroids (inhaled or systemic due to reduced hypoglycemic effect), and subjects on other hormones (LHRH analogs etc).
15. Subjects with any type of bioimplant activated by mechanical, electronic, or magnetic means (e.g. cochlear implants, pacemakers, neuron or biostimulators, electronic infusion pumps, etc.)
16. Subjects with any type of metallic implant that could potentially be displaced or damaged during MRI, such as aneurysm clips, metallic skull plates, surgical implants etc. or metal containing tattoos
17. Anxiety of small spaces and/or claustrophobia
18. Uncontrolled cardiac impairment, circulatory impairment, or inability to perspire (poor thermoregulatory function)
19. Significant sensory or motor impairment
20. Epilepsy, particularly photo-sensitive epilepsy, which may place the individual at a higher risk for adverse events during fMRI scanning with visual stimulation
21. Subjects with neurological problems which may interfere with or complicate testing (e.g. presence of titubation)
22. Body weight above the limitation of the MRI scanning table (330lbs/150 Kg) or body dimensions that could difficult the performance of the scan.
23. Subjects who cannot adhere to the experimental protocol for any reason
24. Anemia with Hgb less than 10
25. Uncontrolled infectious diseases (e.g. HIV, hepatitis, chronic infections etc)
26. Any uncontrolled endocrine condition, e.g. Cushing's, Acromegaly, etc
27. Any cancers or lymphoma
28. Eating disorders like anorexia, bulimia
29. Weight loss surgery or gastrectomy
