Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The aim of this study is to assess which type of dietary strategy is the most effective for patients with morbid obesity who are about to undergo weight loss (bariatric) surgery. It is thought that a low calorie diet will be more effective than a very low calorie diet (e.g. it will reduce surgical complications and length of hospital stay).

Who can participate?
Patients with morbid obesity undergoing bariatric surgery

What does the study involve?
Participants are randomly allocated to follow a very low calorie diet or a low calorie diet for 21 days before surgery. Body measurements, blood parameters, liver volume by CT scan, and compliance with the intervention are measured before and after the intervention.

What are the possible benefits and risks of participating?
In the short term, it is not expected that the results obtained may directly benefit the participant, although they could be of interest for future patients undergoing bariatric surgery. The study does not pose any additional risk apart from providing blood samples and undergoing CT scans.

Where is the study run from?
Hospital Universitari Sant Joan de Reus (Spain)

When is the study starting and how long is it expected to run for?
September 2014 to July 2017

Who is funding the study?
Nestle S.A.

Who is the main contact?
Dr Jordi Salas Salvado

Trial website

Contact information



Primary contact

Dr Jordi Salas Salvado


Contact details

Human Nutrition Unit
Faculty of Medicine and Health Sciences
Universitat Rovira i Virgili
C/Sant Llorenç 21

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Effects of two preoperatory weight loss diets on hepatic volume and surgical complications in morbid obese bariatric surgery candidates: a randomized clinical trial


Study hypothesis

Pre-operative weight loss in patients with morbid obesity candidates for bariatric surgery through the use of a Low Calorie Diet (LCD) will be more effective than a Very Low Calorie Diet (VLCD) on the preservation of protein and immune status, reduction of surgical complications, hospital stay and will be equally effective in terms of reduction in liver volume.

Ethics approval

Ethical committee of the University Hospital Sant Joan de Reus, 29/01/2015, CEIC reference project: 14-09-18 / 9proj4, reference CEIC esmena: 15-01-29 / 1esmproj1

Study design

Single-center randomized parallel trial

Primary study design


Secondary study design

Randomised parallel trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Influence of two types of pre-surgery diets on the decrease of hepatomegaly in morbidly obese candidates for bariatric surgery


Subjects will be randomized with a 1:1 ratio using an excel randomization table to follow a very low calorie diet (VLCD) or a low-calorie diet (LCD) for a period of 21 days. Both dietary interventions had the same percentage of macronutrients (46.8% carbohydrates, 36.4% protein, 9.3% fat, and 7.4% fiber). The total amount of energy administered with the VLCD (4 sachets of Optifast®; Nestlé Health Science; 2011) will be 800 kcal/day, broth and non-calorie beverages allowed. The LCD diet consisted of a defined fixed diet containing 1200 kcal/day also using two sachets of Optifast®.

Intervention type



Drug names

Primary outcome measure

Hepatic volume through computed tomography at baseline and 21 days after dietary intervention

Secondary outcome measures

1. Body weight and anthropometry parameters at baseline and at 21 days of intervention
2. Leukocyte count and serum albumin, prealbumin and total proteins at baseline and at 21 days of intervention
3. Renal and hepatic function parameters at baseline and at 21 days of intervention
4. Surgery complications (between surgery until 6 months after surgery) and hospital stay length (during the hospital stay)
5. Dietary compliance and acceptability, assessed weekly during the first 3 weeks of the intervention

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

BMI ≥ 40 kg/m2 or BMI between 35-40 kg/m2 with associated major comorbidities undergoing bariatric surgery

Participant type


Age group




Target number of participants

80 effectively randomized participants: 40 in each group

Participant exclusion criteria

The same criteria established by hospital protocol for patients undergoing bariatric surgery

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Hospital Universitari Sant Joan de Reus
Avinguda Dr Josep Laporte, 2
Reus (Tarragona)

Sponsor information


Hospital Universitari Sant Joan de Reus

Sponsor details

Avinguda Dr Josep Laporte
Reus (Tarragona)

Sponsor type

Hospital/treatment centre



Funder type


Funder name

Nestle S.A.

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

The protocol and statistical plan are not available. Planned publication of the results in a high-impact peer reviewed journal.

IPD sharing statement
The data sharing plans for the current study are unknown and will be made available at a later date.

Intention to publish date


Participant level data

To be made available at a later date

Basic results (scientific)

See additional file ISRCTN16967604_BasicResults_29Aug18.pdf

Publication list

2018 results in:

Publication citations

Additional files

Editorial Notes

30/08/2018: The basic results of this trial have been uploaded as an additional file. 28/08/2018: Publication reference added.