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Can a Two-Week diet make Weight-Loss surgery easier?

NCT ID NCT04433338

Disease control Sponsor: Rijnstate Hospital Source: ClinicalTrials.gov ↗

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing This study
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Sep 24, 2026 · Last updated Sep 25, 2026 · Updated 1 time

Summary

Researchers are studying whether a 14-day low-calorie diet before Roux-en-Y gastric bypass surgery changes how the operation goes and how much weight patients lose afterward. The diet uses Modifast meal replacements along with vegetables, lean protein, oil, and water. About 80 adults with severe obesity who are scheduled for a first-time gastric bypass will take part. The team will measure how long the surgery takes and how difficult surgeons find ten steps of the procedure.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
a 14-day low-calorie diet using Modifast meal replacements plus vegetables, lean protein, oil, and water
What this could lead to
If it works, a short pre-surgery diet could become a standard step that makes gastric bypass operations faster and easier for surgeons, and may help patients lose more weight afterward.
What could go wrong
The trial is small and the evidence on preoperative weight loss is mixed, so the diet may not clearly improve surgery or lasting weight loss. Some patients may find the strict 14-day diet hard to follow.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Not a phased trial

Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.

Participants

About 80 people

The number the study aims to enrol. It can still change while the study runs.

Started

Sep 2020

Expected to finish

Jul 2027

An estimate. End dates often move.

Lead sponsor

Other sponsor

The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 to 65 years

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Undergoing primary RYGB surgery (meeting all criteria + approval of surgeon) * Able to prepare the meal replacements at home Exclusion Criteria: * Undergoing another bariatric procedure than primary RYGB. * Diabetes Mellitus * Contraindication for the usage of Modifast meal replacements: * Allergy or intolerance to any substance in the used meal replacements (Soy, milk, gluten, egg, peanuts, nuts and seeds) * Veganism * Kidney failure (GFR \< 90 ml/min/1.73m2), liver failure or cardiac insufficiency * A heart attack (myocardial infarct) in the past twelve months * Cancer * Hypokalaemia: serum potassium level \<3.4 mmol/l * Phenylketonuria \& Porphyria

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Conditions

The condition(s) this trial relates to.

morbid obesity Weight Loss

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Bariatric surgery Morbid obesity

Contacts and locations

Locations

  • Rijnstate Hospital

    Arnhem, Gelderland, 6811AD, Netherlands

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