Low-calorie, high-protein diet before weight-loss surgery

NUTritional Impact of a Hypocaloric Hyperprotein Diet Before Obesity Surgery

Not applicable Interventional University Hospital, Rouen · NCT04942093

This project will try whether a short low-calorie, high-protein diet before sleeve gastrectomy reduces liver fat and weight in adults with severe obesity.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment200 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorUniversity Hospital, Rouen Academic / other
Locations3 sites (Dieppe and 2 other locations)
Trial IDNCT04942093 on ClinicalTrials.gov

What this trial studies

The trial compares a preoperative low-calorie, high-protein dietary program to no specific preoperative diet in adults scheduled for sleeve gastrectomy. Participants who meet inclusion criteria will be assigned to either receive the diet for the preoperative period or continue usual care, with adherence and tolerance monitored. Primary outcomes focus on liver size/fat load and preoperative weight loss, and secondary outcomes include surgical conditions and short-term perioperative safety. The design follows prior evidence suggesting a roughly 4-week diet can rapidly reduce liver volume, and the study will measure whether that translates into clinical benefits.

Who should consider this trial

Good fit: Adults aged 18–65 with morbid obesity (BMI ≥ 40) who are eligible and scheduled for sleeve gastrectomy, speak French, meet basic lab and contraception requirements, and provide informed consent.

Not a fit: People who are not candidates for bariatric surgery, have medical contraindications, cannot follow the diet, are pregnant, or have lower BMIs are unlikely to benefit from this intervention.

Why it matters

Potential benefit: If successful, the diet could shrink the liver and abdominal fat before surgery, making the operation easier and reducing surgical risk.

How similar studies have performed: Previous trials and a 2016 meta-analysis reported that short low-calorie, high-protein preoperative diets effectively reduce liver volume and fat, so this approach has supporting evidence.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Patient eligible for bariatric surgery (according to HAS criteria) whose sleeve gastrectomy is scheduled
* Patient with morbid obesity (BMI ≥ 40)
* Age ≥ 18 years and ≤ 65 years
* Haemoglobinemia ≥ 12 g/dL in men and ≥ 11 g/dL in women
* Patient speaking and understanding French
* Adult having read and understood the information letter and signed the consent form
* Woman of childbearing age with effective / very effective contraception (Cf. CTFG) (estrogen-progestin or intrauterine device or tubal ligation) prior to surgery and a negative -HCG blood pregnancy test at inclusion, for the duration of the study
* Postmenopausal woman: confirmatory diagnosis (non-medically induced amenorrhoea for at least 12 months prior to the inclusion visit)
* Patient affiliated with, or beneficiary of a social security (health insurance) category

Exclusion Criteria:

* Contraindication to bariatric surgery detected during the preoperative assessment
* Medical contraindication to a restrictive diet
* Type I or II insulin-requiring diabetes
* Severe renal insufficiency defined by a blood filtration rate \< 30 mL/min
* Person wearing a pacemaker or any other implant with the same functions (cochlear implant, bladder battery, etc.)
* Person deprived of liberty by an administrative or judicial decision or person placed under judicial protection / sub-guardianship or curatorship
* A history of illness or psychological or sensory abnormality likely to prevent the subject from fully understanding the conditions required for participation in the protocol or to prevent him/her from giving informed consent

Where this trial is running

Dieppe and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Diet, HealthyObesity, VisceralBariatric Surgery Candidatedietobesitybariatric surgery
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.