Inclusion Criteria:  Provision of signed and dated informed consent form Stated willingness to comply with all study procedures and availability for the duration of the study (up to 18 months: 6-month treatment plus 12-month follow up) Have a BMI ≥30 (or BMI ≥27 with a medical comorbidity) and BMI ≤50 kg/m2 Have had laparoscopic Roux-en-Y gastric bypass or sleeve gastrectomy Suboptimal weight outcomes after MBS Be an otherwise healthy subject without uncontrolled medical problems, as determined by the study physician and medical co-investigators (physical examination, laboratory studies). Have had a physical in the past year Read, comprehend, and write English at a sufficient level to complete study-related materials. For females of reproductive potential: use of highly effective contraception and agreement to use such a method during study participation For males of reproductive potential: use of condoms or other methods to ensure effective contraception with partner  Exclusion Criteria:  Has a predisposition to seizures (e.g., subject with a history or evidence of seizure disorder, febrile seizures during childhood, brain tumor, cerebrovascular disease, or significant head trauma; has a family history of idiopathic seizure disorder or is currently being treated with medications or treatment regimens that lower seizure threshold). Has a history of anorexia nervosa or history of bulimia nervosa. Is currently taking a medication that is a contraindication to NB medication (e.g., MAOI, opiates). Is currently using other medications for weight loss. Has a history of allergy or sensitivity to bupropion or naltrexone. Has a co-existing psychiatric condition that requires hospitalization or more intensive treatment (such as bipolar mood disorders, psychotic illnesses, or severe depression) Has untreated hypertension with a seated systolic blood pressure > 160 mmHg, diastolic blood pressure > 100 mmHg, or heart rate > 100 beats/minute. Has a history of congenital heart disease, cardiovascular disease, cardiac arrhythmias requiring medication, or a history of cerebrovascular pathology including stroke. Has current uncontrolled hypertension. Has current uncontrolled Type I or Type 2 diabetes mellitus. Has untreated hypothyroidism with a TSH > 1.5 times the upper limit of normal for the test laboratory with repeat value that also exceeds this limit. Has gallbladder disease. Has a history of severe renal, hepatic, neurological, chronic pulmonary disease, or any other unstable medical disorder. Has a recent history of drug or alcohol dependence. Is currently in active effective treatment for eating or weight loss such as behavioral weight loss of FDA-approved weight loss medications. Is currently participating in another clinical study in which the subject is or will be exposed to an investigational or a non-investigational drug or device. Is breast-feeding or is pregnant or is not using a reliable form of birth control. Reports active suicidal or homicidal ideation. Has poor eye health