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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
FORMULITE versus traditional very low calorie diet (VLCD) for weight loss prior to Bariatric Surgery
Scientific title
Assessing compliance and efficacy of FORMULITE versus traditional very low calorie diet (VLCD) for weight loss in obese adults prior to Bariatric Surgery
Secondary ID [1] 289634 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 299424 0
Non-alcoholic fatty liver disease 299425 0
Condition category
Condition code
Diet and Nutrition 299404 299404 0 0
Oral and Gastrointestinal 299799 299799 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Study type
Description of intervention(s) / exposure
This randomised controlled trial will compare the traditional very low calorie diet (VLCD) (Optifast) with a new formulation (Formulite). This aims to assess compliance and GI symptoms prior to bariatric surgery.

The usual regime for VLCD (e.g. Optifast, Formulite or other) prior to bariatric surgery involves:
- 3 meal complete replacement with 3 satchets of VLCD (mixed with water to form a milkshake)
- plain steamed green or leafy vegetables (as much or as little)
- black coffee or tea if desired (as much or as little)
- Water as desired
- No other foods or drinks
For this study, patients will follow this usual regime for the Formulite arm and Optifast arm.

Energy per 55g serve = 858kj

The VLCD regime is used for 2 weeks prior to surgery. The main purpose of the regime is to reduce liver size, aiding in the ease and feasibility of the operation which requires access to the upper stomach. This can be obscured if the liver is large, as is the case in obesity.

Adherence to the regime will be monitored by packets of VLCD remaining, as well as urinary ketones measured weekly during the trial.
Intervention code [1] 295248 0
Treatment: Other
Comparator / control treatment
Comparator - Traditional VLCD (Optifast)

The traditional VLCD regime is identical to the Formulite VLCD regime (as above).
Energy per satchet = 635 - 875kJ
Control group

Primary outcome [1] 298875 0
Compliance with very low calorie diet (VLCD), as defined by:
- urinary ketones (to assess ketosis - Primary assessment)
- remaining VLCD after two weeks
Timepoint [1] 298875 0
Two weeks
Secondary outcome [1] 325511 0
Gastrointestinal symptoms:
- e.g. abdominal bloating, nausea, diarrhoea, constipation.
A study diary will be kept during the 2 week trial. These will also be a questionnaire and interview at the end of the 2 week trial (Likert scale - previously validated) .
Timepoint [1] 325511 0
Two weeks
Secondary outcome [2] 325512 0
Patient quality of life (SF-36)
Timepoint [2] 325512 0
Two weeks
Secondary outcome [3] 325513 0
Liver size, as assessed by peri-operative MRI
Timepoint [3] 325513 0
Two weeks
Secondary outcome [4] 326623 0
Weight loss, assessed using digital scales
Timepoint [4] 326623 0
2 weeks
Secondary outcome [5] 326672 0
Acceptability of VLCD (Likert scale - validated)
Timepoint [5] 326672 0
2 weeks after starting VLCD (time of operation)

Key inclusion criteria
Obese adult participants undergoing bariatric surgery
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Unfit for bariatric surgery

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Meal replacements will be provided by the manufacturer (Formulite (trademark)) and Optifast (trademark) will be purchased. Both will be repackaged in identical plain packs. Sufficient product for two weeks will be provided to each patient at the initial visit. Patients will commence the meal replacement programme 2 weeks prior to the date of their scheduled surgery.
The random assignment of eligible patients will be computer generated by the Monash University School of Public Health and Preventative Medicine (SPHPM) data centre which employs this type of system for all major trials. A telephone based system will be established which will allow a check of patent eligibility and randomisation only proceed if the patient meets the criteria. Randomisation will be clustered to ensure even distribution.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
The random assignment of eligible patients will be computer generated by the Monash University School of Public Health and Preventative Medicine (SPHPM) data centre which employs this type of system for all major trials. Randomisation will be clustered to ensure even distribution.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
All data from the study will be managed by the data-centre within CORE. Outcomes will be analysed by an independent biostatistician from the Monash University SPHPM according to intention-to-treat principles. For the primary endpoint, a 95% CI for the difference in proportions between groups will be inspected and equivalence will be declared if the ends of the CI both fall within the equivalence margin (-5%, +5%). If necessary, a secondary set of analyses will be performed to adjust for baseline characteristics that are found to be imbalanced between groups where imbalance is pre-specified as a 0.25 standard deviation difference in means (quantitative measures) or an odds ratio of 1.5 (binary measures). Multivariate analysis will be performed using multiple logistic regression for binomial outcomes adjusting for baseline imbalances and potential covariates. Data analysis will be completed by an independent statistician who will be blinded to the allocation of groups. We will analyze by Intent to Treat, Last Observation Carried Forwards (ITT LOCF), Observed case and by Completer analysis, to give estimates of the effect size based on each of these scenarios.

Compliance with current VLCD is 86% at two weeks. 80% of patients who failed to comply stated this was due to taste and GI side effects. We therefore anticipate that Formulite will ameliorate these issues and there will be 90+/-10% compliance with Formulite. Assuming an alpha of 0.05 and power of 0.8, 30 patients will be required for each arm of the study. Based on our previous experience we would anticipate a 20% drop out rate, we will aim to recruit 76 patients.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 6130 0
The Avenue Private Hospital - Windsor

Funding & Sponsors
Funding source category [1] 294015 0
Name [1] 294015 0
Centre for Obesity Research and Education, Monash University
Address [1] 294015 0
Level 6, The Alfred Centre
99 Commercial Road
Prahran, VICTORIA, 3181
Country [1] 294015 0
Primary sponsor type
Centre for Obesity Research and Education, Monash University
Level 6, The Alfred Centre
99 Commercial Road
Prahran, VICTORIA, 3181
Secondary sponsor category [1] 292835 0
Name [1] 292835 0
Address [1] 292835 0
Country [1] 292835 0

Ethics approval
Ethics application status
Ethics committee name [1] 295427 0
The Avenue Hospital
Ethics committee address [1] 295427 0
40 The Avenue
Windsor, VICTORIA, 3181
Ethics committee country [1] 295427 0
Date submitted for ethics approval [1] 295427 0
Approval date [1] 295427 0
Ethics approval number [1] 295427 0

Brief summary
Obesity is one of the most prevalent and challenging diseases affecting our community. According to the latest census figures, 63.4% of Australians aged 18 years and over were overweight or obese, namely, 35.0% overweight and 28.3% obese. Along with the increase in our community BMI has been a burgeoning of obesity related diseases including type II diabetes, cardiovascular disease, osteoarthritis, hypertension, liver disease, depression and infertility. Weight loss leads to a significant improvement in these conditions.

Currently the only durably effective treatment for the most severe grades of obesity is bariatric surgery. Conservative programs are effective in the short-term, however, only 3% of successful weight losers are able to maintain a meaningful weight loss beyond 2 years.

Pre-operative weight loss with a short term very low calorie diet (VLCD) has been shown to improve surgical access by reducing liver volume as well as the metabolic status of the patient, reducing the number of postoperative complications. For this reason, most clinicians request their patients to undertake a preoperative weight loss programme for a minimum of two weeks.

Whilst clinicians perceive a benefit for preoperative weight loss, patients often struggle to comply. One reason for this is the difficulty complying with the currently available VLCD. Most are based on liquid formulations and patients struggle with the taste and texture of the product. Patients regularly report bloating, abdominal discomfort and constipation. In addition, the nutritional construct is often based around a large amount of sugar, and lacks high quality protein and fibre.

Formulite (Trademark) is a new VLCD that the manufacturers claim retains the benefit of traditional VLCD, inducing Ketosis thereby avoiding hunger, whist reducing the unwanted GI side effects by combining high quality proteins with soluble fibre, less sugar and probiotics. These changes are supposed to improve patient compliance.

We wish to confirm potential benefits of Formulite in patients undergoing bariatric surgery. We hypothesised that patient satisfaction would be higher and therefore compliance with the preoperative weight loss programme would be improved when compared with traditional VLCD.

HYPOTHESIS: Compliance with Formulite is better than traditional VLCD prior to bariatric surgery in obese adults.

- To measure patient compliance with Formulite compared to traditional VLCD
- To determine if there are improved gastrointestinal symptoms with Formulite compared to traditional VLCD
- To assess patient satisfaction with Formulite compared to traditional VLCD
- TO measure peri-operative liver volume and weight loss following 2 weeks of Formulite when compared to traditional VLCD
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 67262 0
Prof Wendy Brown
Address 67262 0
CORE, Monash University,
Level 6, The Alfred Centre
99 Commercial Road, Prahran, VICTORIA, 3181
Country 67262 0
Phone 67262 0
+613 9903 0725
Fax 67262 0
+613 9903 0717
Email 67262 0
Contact person for public queries
Name 67263 0
Ms Cheryl Laurie
Address 67263 0
CORE, Monash University,
Level 6, The Alfred Centre
99 Commercial Road, Prahran, VICTORIA, 3181
Country 67263 0
Phone 67263 0
+613 9903 0725
Fax 67263 0
+613 9903 0717
Email 67263 0
Contact person for scientific queries
Name 67264 0
Dr Geraldine Ooi
Address 67264 0
CORE, Monash University
Level 6, The Alfred Centre
99 Commercial Road, Prahran, Victoria, 3181
Country 67264 0
Phone 67264 0
+613 9903 0725
Fax 67264 0
+613 9903 0717
Email 67264 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary
INTRODUCTION: Very Low Energy Diets (VLED) improves surgical access during weight loss surgery by reducing liver volume. However, compliance rates with traditional VLED are variable, mainly due to gastrointestinal side effects. Formulite is a new formulation of VLED, with higher protein, soluble fibre and probiotics. These changes are theorised to improve GI side effects thus improving compliance.
AIMS: To directly compare traditional VLED (Optifast) with the new high protein, fibre and probiotic VLED formulation (Formulite), and assess participants’ compliance, weight loss, side effects, and surgical access.
METHODS: This was a randomised double-blinded study involving patients scheduled for weight loss surgery. We measured compliance, weight loss, satisfaction, side effects and ease of operating.
RESULTS: There 35 participants in the Formulite group and 34 in the Optifast group. Urinary ketones at 2 weeks was higher in the Formulite group. Total body weight loss percentage and ease of surgery were not significant in both groups. Formulite produced less GI side effect compared to Optifast, however Optifast was ranked higher in terms of taste and satisfaction.
CONCLUSIONS: This study suggested better ketosis, and therefore compliance, with the high protein high fibre formulation, with decreased GI side effects. However, this did not translate to better satisfaction, weight loss or surgeons’ perception of surgical access.