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Trial registered on ANZCTR

Registration number

ACTRN12614000141640

Ethics application status

Approved

Date submitted

16/01/2014

Date registered

5/02/2014

Date last updated

3/04/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

Investigation of the Impact of Degree of Weight Loss on Physiological Adaptations to Weight Loss

Scientific title

An interventional study investigating if starting BMI or degree of weight loss affect physiological adaptations to weight loss using a VLED (very low energy diet)

Secondary ID [1]

nil

Universal Trial Number (UTN)

U1111-1146-9120

Trial acronym

nil

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Obesity

Condition category

Condition code

Diet and Nutrition

Obesity

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Very Low Energy Diet (VLED) (OptiFast) for 12 weeks. All participants will be placed on OptiFast for a duration of 12 weeks. The OPTIFAST program is a total food
replacement for the overweight. It is intended for use as part of the management of the moderately to severely overweight persons. The OPTIFAST program has been clinically developed and scientifically formulated to totally replace normal food intake. Weight loss is comparable to that achieved by total fasting whilst minimising the complications of severe ketosis and muscle loss. The OPTIFAST formulation includes high quality protein, sufficient quantities of protein (for nitrogen sparing
and to preserve lean body mass), carbohydrates, fatty acids, and follows the Recommended Dietary Intake (RDI) for vitamins, minerals and trace elements. Fortnightly measurements of urinary ketones will be taken to gauge adherence to diet.

Intervention code [1]

Treatment: Other

Comparator / control treatment

Overweight adults compared to obese adults

Control group

Uncontrolled

Outcomes

Primary outcome [1]

Degree of reduction in body weight required to bring about compensatory mechanisms (assessed using weight measurements via calibrated scales, measurements of gut hormones (amylin, PYY, GLP-1, leptin ,ghrelin, GIP,PP and INSL5)glucose, insulin and free fatty acids via serum assays)

Timepoint [1]

12 weeks

Primary outcome [2]

To investigate if body weight is equally regulated across a range of BMIs (assessed using weight measurements via calibrated scales, measurements of gut hormones (amylin, PYY, GLP-1, leptin ,ghrelin, GIP,PP and INSL5)glucose, insulin and free fatty acids via serum assays)

Timepoint [2]

week 64

Secondary outcome [1]

Degree of weight regain from week 13-64 (assessed via weight measurements using calibrated scales)

Timepoint [1]

week 64

Secondary outcome [2]

Change from baseline to week 12; and week 13-64 in gut hormone measurements, fasting glucose measurement, fasting insulin measurement and appetite (as measured by visual analogue scale)(assessed using weight measurements via calibrated scales, measurements of gut hormones (amylin, PYY, GLP-1, leptin ,ghrelin, GIP,PP and INSL5)glucose, insulin and free fatty acids via serum assays)

Timepoint [2]

week 64

Eligibility

Key inclusion criteria

*Written informed consent obtained
*Age 18 – 65 years
*BMI 25-50kg/m2
*Stable body weight
*In good health

Minimum age

18 Years

Maximum age

65 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

*Body builders
*Significant illness
*History of recent weight loss
*Past history of bariatric surgery
*Use of weight affecting pharmacotherapy
*Current smokers
*History of unstable thyroid disorder

Study design

Purpose of the study

Treatment

Allocation to intervention

Non-randomised trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Masking / blinding

Open (masking not used)

Who is / are masked / blinded?

Intervention assignment

Parallel

Other design features

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

The power calculations for this study were based on the expected change in ghrelin levels after weight loss. We propose that average percentage change in ghrelin between the 5% weight loss measurement and 15% weight loss measurement is at least in the vicinity of 0%. To account for natural variation not associated with weight loss we suppose that the percentage change between these two time periods is SD = 25. We assume that equivalence proven if mean percentage change is within +/- 10%. Assuming SD=25%, 70 subjects are required to achieve a power of 90%. To account for attrition, it is proposed that a total recruitment of 100 subjects as an appropriate sample size to study based on an expected attrition rate of 30%.

Additional to the exploration of equivalence between groups, for comparisons between two time points, changes in measurements will be analysed using either a paired t-test or the non-parametric Wilcoxon signed-rank test as appropriate. Changes in hormones and VAS will be analysed using linear mixed effect (lme) models to factor in fixed effects week (i.e. week of visit), time (time of measurement within week), , subject as the random effect and will also allow for adjustment and analysis with respect to covariates. Additionally, changes in hormones will also be modelled using various baseline anthropometric predictors and change in these measures after phase I.

Recruitment

Recruitment status

Active, not recruiting

Date of first participant enrolment

Anticipated

Actual

5/02/2014

Date of last participant enrolment

Anticipated

31/12/2015

Actual

5/06/2015

Date of last data collection

Anticipated

31/12/2018

Actual

Sample size

Target

100

Accrual to date

Final

104

Recruitment in Australia

Recruitment state(s)

VIC

Recruitment hospital [1]

Austin Health - Heidelberg Repatriation Hospital - Heidelberg West

Recruitment postcode(s) [1]

3081 - Heidelberg Heights

Funding & Sponsors

Funding source category [1]

University

Name [1]

University of Melbourne

Address [1]

1—100 Grattan Street,
Parkville, Victoria, 3010

Country [1]

Australia

Primary sponsor type

University

Name

University of Melbourne

Address

1—100 Grattan Street,
Parkville, Victoria, 3010

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Austin Health HREC

Ethics committee address [1]

145 Studley Rd
Heidelberg VIC 3084

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

Approval date [1]

14/11/2013

Ethics approval number [1]

HREC/13/Austin/154

Summary

Brief summary

There is evidence that public health measures aimed at reducing the burden of obesity have not been effective. Whilst there are several possible reasons for this, including a multitude of competing messages, the overabundance of energy dense food and the near absence of obligatory physical activity, it is likely that the more important reason is the fact that weight appears to be physiologically regulated and defended. This means that using public health measures to combat obesity is not likely to work for obese subjects. What is not yet known is if subjects who are overweight (as opposed to obese), defend weight loss, nor is it known if modest (~5%) weight loss is defended. If overweight or modest weight losses are not defended, it would allow the targeting of public health messages towards the overweight and to focus on modest weight loss in the obese.
This study aims to investigate if overweight people defend weight loss as vigorously as obese people, and to determine at what degree of weight loss these physiological changes begin. Overweight and obese people will be recruited and placed on a VLED (very low energy diet) for a period of 12 weeks, aiming to decrease body weight by 15%. Measurements in body weight and a number of biomarkers will be taken at proscribed intervals. All participants will be followed up for a period of two years, to observe weight regain (if any).  Gut hormone and other biomarker changes over the trial will be compared between the overweight cohort and the obese cohort, to determine any differences. For both cohorts, changes in gut hormones and other biomarkers will be compared at 5%, 10% and 15% baseline body weight lost, to determine when physiological defences increase.

Trial website

Trial related presentations / publications

Edwards KL, Kalfas S, Prendergast LA, Proietto J. Investigation of the impact of degree of weight loss on physiological adaptations to weight loss.
(Poster presentation at Australian and New Zealand Obesity Society Annual Scientific Meeting 2014)

Kira Edwards, Luke Prendergast, Stefanie Kalfas, Priya Sumithran, Joseph Proietto.  Effect of weight loss on plasma INSL5 in humans. 
(Poster presentation at the European Congress on Obesity 2017)

Kira Edwards, Luke Prendergast, Stefanie Kalfas, Priya Sumithran, Joseph Proietto. The Relationship between Degree of Weight Loss and Changes in Gut Hormones that Control Hunger and Satiety.
(Oral Presentation at the Australian and New Zealand Obesity Society Annual Scientific Meeting 2017; Finalist, ANZOS Early Career Researcher Awards)

Public notes

Contacts

Principal investigator

Name

Prof Joseph Proietto

Address

University of Melbourne, Department of Medicine
L2 Boronia Centre, Heidelberg Repatriation Hospital
300 Waterdale Rd
Heidelberg Heights VIC 3081

Country

Australia

Phone

+61 3 9496 2250

Fax

+61 3 9496 2672

[email protected]

Contact person for public queries

Name

Kira Edwards

Address

University of Melbourne, Department of Medicine
L2 Boronia Centre, Heidelberg Repatriation Hospital
300 Waterdale Rd
Heidelberg Heights VIC 3081

Country

Australia

Phone

+61 3 9496 2124

Fax

+61 3 9496 2672

[email protected]

Contact person for scientific queries

Name

Joseph Proietto

Address

University of Melbourne, Department of Medicine
L2 Boronia Centre, Heidelberg Repatriation Hospital
300 Waterdale Rd
Heidelberg Heights VIC 3081

Country

Australia

Phone

+61 3 9496 2250

Fax

+61 3 9496 2672

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Impact of starting BMI and degree of weight loss on changes in appetite-regulating hormones during diet-induced weight loss.	2022	https://dx.doi.org/10.1002/oby.23404

N.B. These documents automatically identified may not have been verified by the study sponsor.

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