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RecruitingNCT06881485RelayUpdated Mar 21, 2025

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

An interventional study of Very Low Calorie Diet in Weight Regain Post Bariatric Surgery and Obesity (Disorder), sponsored by Universitaire Ziekenhuizen KU Leuven. Recruiting at 2 sites in Belgium. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-03-21.

Sponsored by Universitaire Ziekenhuizen KU Leuven · Not applicable, Interventional, and Other

From the registry’s dates

  • Started Jan 2025; still recruiting 1 year 8 months later.
Phase
Not applicable
Study type
Interventional
Enrollment
62
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study summary

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
02

Conditions studied

  • Weight Regain Post Bariatric Surgery
  • Obesity (Disorder)
03

In context

Obesity

6,296 studies on the registry are indexed under Obesity; 1,692 are open to participants now.

This study's planned enrollment of 62 is below the median of 78 across 4,878 interventional studies indexed under Obesity.

Browse Obesity studies →

Lead sponsor

Universitaire Ziekenhuizen KU Leuven is the lead sponsor of 928 studies on the registry; 261 are open to participants now.

Of its 5 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

  • Participants eligible for inclusion in this Trial must meet all of the following criteria:

    1. Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any screening procedures
    2. Use of highly effective methods of birth control; defined as those that, alone or in combination, result in low failure rate (i.e., less than 1% per year) when used consistently and correctly; such as implants, injectables, combined oral contraceptives, some IUDs, true sexual abstinence (i.e. refraining from heterosexual intercourse during the entire period of risk associated with the Trial treatment(s)) or commitment to a vasectomised partner.
    3. Miminum 18 years of age at the time of Informed Consent signature
    4. Underwent bariatric surgery (RYGB or SG) with weight regain ≥10% of nadir weight
    5. People without Type 2 diabetes (T2D) • No history, no drugs, HbA1c \< 6,5% and FPG \<126 mg/dl) All participants that are considered for Trial participation, per the above criteria will be documented on the Screening Log, including Screen Failures.

Exclusion criteria

Exclusion Criteria:

  • Participants eligible for this Trial must not meet any of the following criteria:

    1. Participant has a history of type 2 diabetes mellitus (also drugs, HbA1c > 6,5% and FPG >126 mg/dl)
    2. IFemale who is pregnant, breast-feeding or intends to become pregnant or is of child-bearing potential and not using an adequate, highly effective contraceptive
    3. Participation in an interventional Trial with an investigational medicinal product (IMP) or device
    4. Not willing to sign informed consent
    5. Younger than 18 years of age at the time of Informed Consent signature
    6. Other types of bariatric surgery other than RYGB or SG (including LAGB, BPD)
    7. Underwent bariatric surgery (RYGB or SG) with weight regain \<10% of nadir weight
    8. Contraindication for VLCKD, including CKD stage 4-5, liver cirrhosis, type 1 diabetes mellitus, active gout
    9. Contraindication for NB including the use of opioids, history of CNS tumor or seizures, severe psychiatric disorder or > 2 psychotropic medications, uncontrolled hypertension
    10. Use of other drugs for weight management (e.g. GLP1Ra) in the last 3 months prior to trial intervention
    11. Any disorder, which in the Investigator's opinion might jeopardise the participant's safety or compliance with the protocol Participants who meet one or more of the above exclusion criteria must not proceed to be enrolled/randomized in the Trial and will be identified on the Screening Log as Screen Failure.
05

Study design

Phase
Not applicable
Primary purpose
Other
Allocation
Randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
62 participants (estimated)

Study arms

  • Experimental
    Naltrexon/Bupropion + Lifestyle + VLCKD

    Naltrexon/Bupropion + Lifestyle + VLCKD

    Other: Very Low Calorie Diet

  • No intervention
    Naltrexon/Bupropion + Lifestyle

    Naltrexon/Bupropion + Lifestyle

Interventions

  • OtherVery Low Calorie Diet

    This is a parallel multicentric longitudinal randomized controlled trial in which prospective data will be collected from the electronic health record. The inclusion and exclusion criteria will be checked and afterwards patients will be randomized to (unblinded) medication only or combination with VLCKD. Both arms include NB and lifestyle changes for 26 weeks but the patients belonging to the experimental arm must follow a VLCKD in the first 10 weeks on top of it. Like the other arm, the remaining 16 weeks will consist of NB combined with lifestyle interventions. Afterwards there is a follow-up extension of 26 weeks.

06

What researchers measure

Primary outcomes

  1. To evaluate the superiority of combined VLCKD, intensive lifestyle intervention and naltrexone/bupropion versus standard of care with naltrexone/bupropion on weight loss.

    The percentage of weight loss at 26 weeks

    Time frame: 26 weeks

Secondary outcomes

  1. • A weight loss percentage at 10 weeks, 16 weeks and at end of trial (= 52 weeks from start)

    in %

    Time frame: 10,16 and 52 weeks

  2. • A proportion of patients with a weight loss percentage of 5% or more at 10, 16, 26 and 52 weeks

    in %

    Time frame: 10, 16, 26 and 52 weeks

  3. • A proportion of patients with a weight loss percentage of 10% or more at 10, 16, 26 and 52 weeks

    in %

    Time frame: 10, 16, 26 and 52 weeks

  4. • The time to reach a weight loss percentage of 5% and 10%

    in weeks

    Time frame: 52 weeks

  5. • The dose of naltrexone/bupropion used at 10, 16, 26 and 52 weeks and at the end of the trial

    the dose is in mg

    Time frame: 10, 16, 26 and 52 weeks

  6. • The tolerability of VLCKD

    The amount of reported adverse effects, in relation to the achieved VLCKD.

    Time frame: 52 weeks

  7. • The tolerability of NB

    The amount of reported adverse effects, in relation to the achieved dose level.

    Time frame: 52 weeks

  8. • The adherence to VLCKD

    The amount meals eaten per day, in accordance to the dietary advice.

    Time frame: 52 weeks

  9. • The adherence to NB

    The amount of tablets taken per day, in accordance with the medicinal advice.

    Time frame: 52 weeks

  10. • The change in fasting glucose at 10, 16, 26 and 52 weeks

    fasting glucose in mg/dl

    Time frame: at 10, 16, 26 and 52 weeks

  11. • The change in lipids at 10, 16, 26 and 52

    lipids in mg/dl

    Time frame: at 10, 16, 26 and 52 weeks

  12. • The change in blood pressure at 10, 16, 26 and 52

    blood pressure in mmHg

    Time frame: at 10, 16, 26 and 52 weeks

07

Study locations

1 of 2 sites recruiting
  • UZ Leuven
    Leuven, Vlaams-Brabant 3000, Belgium
    Recruiting
  • AZ Sint-Jan Brugge
    Brugge, West-Vlaanderen 8000, Belgium
    Not yet recruiting
08

References and documents

Study documents

  • Study protocol · Nov 19, 2024

Documents are hosted by the registry — open the source record to download them.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Mar 21, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT06881485
Lead sponsor
Universitaire Ziekenhuizen KU Leuven
Responsible party
Sponsor
First posted
Mar 18, 2025
Start date
Jan 20, 2025
Primary completion
Jan 1, 2027 (estimated)
Completion
Jan 1, 2027 (estimated)
Last update
Mar 21, 2025

Study contacts

Prof. Dr. R. Vangoitsenhoven
Contact
relaytrial@uzleuven.be
+3216344775

Oversight

FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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