Naltrexone/Bupropion With or Without Very Low Calorie Ketogenic Diet for Weight Regain After Bariatric Surgery

The goal of this clinical trial is to evaluate the superiority of combined VLCKD, intensive lifestyle intervention and naltrexone/bupropion (N/B) versus standard of care with naltrexone/bupropion on weight loss for people with weight regain after bariatric surgery. The main questions it aims to answer are: Primary endpoint: • The percentage of weight loss at 26 weeks Secondary endpoints: * A weight loss percentage at 10 weeks, 16 weeks and at end of trial (= 52 weeks from start) * A proportion of patients with a weight loss percentage of 5% or more at 10, 16, 26 and 52 weeks * A proportion of patients with a weight loss percentage of 10% or more at 10, 16, 26 and 52 weeks * The time to reach a weight loss percentage of 5% and 10% * The dose of naltrexone/bupropion used at 10, 16, 26 and 52 weeks and at the end of the trial * The tolerability of VLCKD and NB * The adherence to VLCKD and NB * The Patient-Reported Outcome Measures (PROMs) of hunger and cravings at 0, 4, 10, 16, 26 and 52 weeks * The change in fasting glucose, lipids and blood pressure at 10, 16, 26 and 52 weeks Researchers will compare an experimental arm (N/B + Lifestyle + VLCKD) with comparator arm (NB + lifestyle) to see if combined VLCKD, intensive lifestyle and N/B is superior. Participants will: * get NB and lifestyle changes for 26 weeks * follow a VLCKD in the first 10 weeks on top of it, if they belong to the experimental arm * follow NB combined with lifestyle the remaining 16 weeks * be followed-up for an extension of 26 weeks * come to the hospital at week 1, 10, 16, 26, 52