A Multiple Health Behavior Change (MHBC) Intervention for Weight Loss and Smoking Cessation for Pre-Bariatric Surgery Patients

Inclusion Criteria: * Be 18-65 years old. * Be actively considering bariatric surgery. * Smoke at least 5 cigarettes daily for the past 3 months. * Have a BMI ≥ 30.0 kg/m2. * Not currently taking medications that interact with Naltrexone or Bupropion (e.g., opiates, benzodiazepines). * No history of medical conditions that are contraindicated with Naltrexone or - Bupropion (e.g., seizure disorders, uncontrolled hypertension, cardiac issues including history of heart attacks, heart disease, or stroke, history of anorexia or bulimia nervosa). * Physically well enough to participate in the intervention (e.g., able to walk independently). * Speak/read/write in English. * Not currently pregnant or breastfeeding or have plans to become pregnant or breastfeed during the study. * No active suicidal or homicidal ideation. Exclusion Criteria: * Has an acute medical or psychiatric disorder that would make participation difficult or unsafe. * Has suicidal or homicidal ideation that requires immediate attention. * 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 evidence of a second or third degree heart block, atrial fibrillation, atrial flutter, prolongation of the QTc, or any other finding on the screening electrocardiogram that would preclude safe participation. * Has stage 2 hypertension (blood pressure greater than 160/100 or heart rate over 100 beats/minute). * Has elevated bilirubin test or any other liver function test value \> 5 times the upper limit of normal laboratory criteria. * Has a platelet count \< 100x10 3/uL. * Has a history of anorexia nervosa or history of bulimia nervosa. * Is currently taking a medication that is contraindicated to Naltrexone or Bupropion (e.g., MAOIs, opiates). * Has a history of allergy or sensitivity to Naltrexone or Bupropion. * Has a co-existing psychiatric condition that requires hospitalization or more intensive treatment (such as bipolar mood disorders, psychotic illnesses, or severe depression). * Has a history of congenital heart disease, cardiovascular disease, cardiac arrhythmias requiring medication, or a history of cerebrovascular pathology including stroke. * Has current uncontrolled Type I or Type 2 diabetes mellitus. * Has a history of severe renal, hepatic, neurological, chronic pulmonary, or gallbladder disease, or any other unstable medical disorder, including cancer. * Has angle closure glaucoma. * Has taken an investigational drug in another study within 30 days of study consent. * Has been prescribed and taken Naltrexone or Bupropion within 30 days of study consent. * Is concurrently enrolled in formal behavioral or pharmacological Substance Use Disorder treatment. * Is receiving ongoing treatment with tricyclic antidepressants, xanthines, systemic corticosteroids, nelfinavir, efavirenz, chlorpromazine, MAOIs, central nervous stimulants, or any medication that could interact adversely with the study medications. * Has a current pattern of alcohol, benzodiazepine, or other sedative hypnotic use which would preclude safe participation in the study. * Requires treatment with opioid-containing medications during the study period. * Has a surgery planned other than bariatric surgery. * Is currently in jail, prison, or any inpatient overnight facility as required by a court of law or have pending legal action or other legal situation that could prevent participation. * Is currently pregnant, breastfeeding, or plans to become pregnant during the study, or is not using a reliable form of birth control.