The PREBA Study: Effect of Preoperative Weight Loss With a 14-day Low-calorie Diet on Surgical Procedure and Outcomes in Patients Undergoing RYGB Surgery

Bariatric guidelines recommend preoperative weight loss of 5% to reduce the risk of surgical complications. However, results in the literature on the improvement of surgical procedure and outcomes are still conflicting.

This study aims to evaluate the effect of preoperative weight loss by means of a 14-day low-calorie diet in bariatric patients on operative time, the ease of the Roux-en-Y gastric bypass (RYGB) procedure and long-term weight loss in a real-life experimental setting.

Study Overview

• Status: Active, not recruiting
• Conditions: Morbid Obesity; Bariatric Surgery
• Intervention / Treatment: Other: 14-day Low Calorie Diet

• Study Type: Interventional
• Enrollment (Estimated): 80
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Netherlands
  • Gelderland
    • Arnhem, Gelderland, Netherlands, 6811AD
      • Rijnstate Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intervention group; Participants in the intervention group will follow a low-calorie diet during 14 days before undergoing surgery. The diet will consist of both meal replacements and regular foods. For women, the diet provides ± 900 kcal, 50 grams of carbohydrates, 85 grams of protein, 30 grams of fat and 25 grams of fibres. For men, the diet provides ± 1000 kcal, 55 grams of carbohydrates, 100 grams of protein, 30 grams of fat and 30 grams of fibres.	Other: 14-day Low Calorie Diet; Participants will be asked to: Use 4 (women) or 5 (men) Modifast meal replacements per day.; Daily consume a minimum of 250 grams of (raw) vegetables without dressing.; Daily consume 100 grams of lean meat/fish/meat analogues.; Daily consume two spoons of liquid oil; Daily drink at least 2.0 litres of water, coffee or tea without added sugar or milk, bouillon or sugar-free drinks.
No Intervention: Control group; Participants in the control group can eat according to the standard nutritional advices provided by their dietitian. These advices are intended to educate participants on the recommended eating pattern after surgery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Operative time of the RYGB procedure	Duration of the surgical procedure, retrieved from the electronic medical record	surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Ease of the RYGB procedure	Ten aspects of the RYGB procedure will be scored on a 5-point Likert scale. The total score can range from 10 to 50, with 10 being the easiest. The ten aspects include: Exerting force on instruments (1=very low, 5= very high); Difficulty of moving the liver (1=very easy, 5=very difficult); Size of the liver (1=very small, 5= very large); Size of omentum (1=very small, 5= very large); Difficulty of approaching pouch (1=very easy, 5=very difficult); Accessibility of Treitz ligament (1=very easy, 5=very difficult); Difficulty of creating pouch (1=very easy, 5=very difficult); Difficulty of measuring small intestine (1=very easy, 5=very difficult); Difficulty of entero-entero connection (1=very easy, 5=very difficult); Difficulty of abdominal wall hernia repair (1=very easy, 5=very difficult)	surgery
Appearance of the patient's liver	Includes four images of the liver in different stages (1= healthy, 2= fatty liver, 3= fatty liver with inflammation, 4= liver cirrhosis). Surgeons will be asked to choose the image that best matches the appearance of the patient's liver.	surgery
Post-operative weight loss	Body weight measurements to assess weight loss after surgery	4 weeks, 3, 6 months and 1, 2, 3, 4, 5 years after surgery

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Feasibility of the diet	Feasibility will be assessed via questionnaires	During the 14-day intervention period
Compliance of the diet	Compliance will be assessed via food records	During the 14-day intervention period
Complication rate	All short term complications during the first 30 days will be recorded and classified according to the Clavien-Dindo classification	First 30 days post-surgery
Wound healing	Degree of wound healing post-surgery will be checked based on appearance on a 5-point Likert scale.	4 weeks

Collaborators and Investigators

• Sponsor: Rijnstate Hospital
• Investigators: Principal Investigator: Eric J Hazebroek, MD, PhD, Vitalys, part of Rijnstate hospital/Wageningen University

Study record dates

Study Major Dates

• Study Start (Actual): September 29, 2020
• Primary Completion (Actual): June 22, 2022
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: June 12, 2020
• First Submitted That Met QC Criteria: June 15, 2020
• First Posted (Actual): June 16, 2020

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 2, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Keywords: Morbid Obesity; Bariatric surgery; Weight Loss; Diet; RYGB
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Body Weight Changes; Overweight; Obesity; Weight Loss; Obesity, Morbid
• Other Study ID Numbers: NL70092.081.19

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No