The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Does the rate of weight loss influence the success of long term weight management?
Scientific title
Randomised Clinical Control trial in Obese Adults Investigating Rapid and Gradual Weight Loss on Weight Maintenance.
Secondary ID [1] 259622 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 261180 0
Condition category
Condition code
Diet and Nutrition 259335 259335 0 0

Study type
Description of intervention(s) / exposure
Phase 1:Weight Loss Phase

Arm 1: Rapid Weight Loss Group- subjects will consume a commercially available VLCD preparation (Optifast(R)) for three months. During this phase 3 meals a day (Breakfast, Lunch and Dinner) will be replaced with a nutritionally sound meal replacement in a liquid form called Optifast (R). To administer these liquid meals participants will add the Optifast(R) powdered sachet (40grms) to 200ml of water and shake vigrously in a closed container. The Optifast shakes are approximately 150-200 calories per shake. The Optifast shakes contain all the energy, macro and micro nutrients required to reach recommended daily intakes (RDIs). Participants will also have biweekly contact with the dietician who will instruct the subjects to follow a VLCD. During this weight loss phase participants will be required to lose at least 15% of their body weight (approximately 1.50kg/week).

Arm 2: Gradual Weight Loss Group- subjects will be instructed bi-weekly by a dietician to follow a weight loss program similar to the Australian Guide to Healthy Eating and at least one meal a day will be replaced with a optifast(R) meal for nine months. During this weight loss phase subjects will be required to lose at least 15% of their body weight (approximately 0.5kg/week).

Phase 2: Weight Maintenance Phase

All participants will be monitored for the following 3 years post phase 1.
Intervention code [1] 258054 0
Treatment: Other
Intervention code [2] 258059 0
Comparator / control treatment
Rapid Weight Loss Group vs Gradual Weight Loss Group
Control group

Primary outcome [1] 262137 0
To compare the weight outcome at three years following rapid or slow weight loss.
Bioelectrical impedance analysis (BIA) will be used to assess this outcome.
Timepoint [1] 262137 0
3 years following diet phase.
Secondary outcome [1] 273219 0
To determine the impact of personality, social functioning and motivation to the maintenance of weight loss at two different rates.
The following questionnaires will be used to assess this outcome: the following validated questionnaires: The Big Five Inventory (to assess personality type); Social Provisions Scale (to assess social supports); The Ways of Coping Checklist (Revised WCCL-R) (to assess coping skills); The Weight Locus of Control Scale (to assess perceived locus of control) and the Three Factor Eating Questionnaire (to assess eating behaviours)
Timepoint [1] 273219 0
At the end of diet phase and 3 years following diet phase
Secondary outcome [2] 276529 0
To compare short and long term physiological adaptations following weight loss at two different rates. In order to assess this outcome blood will be collected pre-intervention, following the diet phase (3 and 9 months) and annually for three years during the weight maintenance phase for the analysis of the following nutrients and hormones: Insulin, glucose, leptin, ghrelin, cholecystokinin (CCK) at both a fasting and post-prandial state.
Timepoint [2] 276529 0
At the end of diet phase and 3 years following diet phase

Key inclusion criteria
Inclusion criteria
The criteria for inclusion in the trial are:
*Healthy men and women aged 18-70 years with a desire to lose weight
*Weight stable for 3 months
*BMI >30kg/m2
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
*Pregnancy or breast feeding
*History of surgical procedures or laxative abuse for weight loss
*The use of any VLCD or weight lowering drugs in the past three months
*Known major weight change in the previous six months (>10% body weight)
*Inability to attend scheduled examinations and visits
*Inability to follow the study instructions, or unlikely to be compliant to the dietary prescription provided
*For females taking an oral contraceptive pill: dose must have been stable for the past three months
*For females using hormone replacement therapy: dose must have been stable for past 3 months
*For participants receiving thyroid preparations or thyroxin treatment: dose must have been stable for the past three months
*Surgical intervention planned during the study
* Any recent (less than six months) cessation of smoking and current smokers
*Participation in another study, or administration of any investigational drug in the past three months
*Uncontrolled and clinically significant disease or known malignancy that could interfere with the study conduct
*Presence of any clinically significant renal or endocrine disease (including diabetes) according the Investigator or as revealed by screening blood tests

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants were recruited using radio, newspaper advertisements and word-of-mouth. A written participant information and consent form was sent to each potential participant and they were encouraged to read and discuss the form with family and their doctors and to ask any questions during their first visit and before signing the consent form.
Subjects were randomised to the rapid and gradual weight loss groups using a randomised block design with random block sizes that accounts for potential confounding factors such as gender, age and BMI. A research assistant located away from the clinic and not involved with the study held the randomisation list and under the supervision of the study statistician allocated participants to treatment groups. The research assistant kept the randomisation sequence private, only revealing a treatment allocation after receiving information demonstrating that the participant was eligible and had consented to the trial. Investigators (other than the study statistician) did not have access to the randomisation list at any time during the duration of the trial.
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
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

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] 1372 0
Austin Health - Heidelberg Repatriation Hospital - Heidelberg West
Recruitment postcode(s) [1] 7233 0
3081 - Heidelberg Heights

Funding & Sponsors
Funding source category [1] 258524 0
Government body
Name [1] 258524 0
National Health and Medical Research Committee
Address [1] 258524 0
Level 1
16 Marcus Clarke Street
Canberra ACT 2601
Country [1] 258524 0
Primary sponsor type
The University of Melbourne
Level 1, Boronia Centre,
Heidelberg Repatriation Hospital,
300 Waterdale Rd,
Heidelberg Heights,
Victoria 3081
Secondary sponsor category [1] 257660 0
Name [1] 257660 0
Address [1] 257660 0
Country [1] 257660 0
Other collaborator category [1] 251818 0
Name [1] 251818 0
Austin Health
Address [1] 251818 0
Henry Buck Building
Austin Hospital
145 Studley Road
Australia, 3084
Country [1] 251818 0
Other collaborator category [2] 251819 0
Name [2] 251819 0
The University of Melbourne
Address [2] 251819 0
The University of Melbourne
Victoria 3010
Country [2] 251819 0

Ethics approval
Ethics application status
Ethics committee name [1] 289678 0
Austin Health Human Research Ethics Committee
Ethics committee address [1] 289678 0
Research Ethics Unit
Austin Hospital
145 Studley Rd
PO box 5555 Heidelberg
Victoria 3084
Ethics committee country [1] 289678 0
Date submitted for ethics approval [1] 289678 0
Approval date [1] 289678 0
Ethics approval number [1] 289678 0

Brief summary
This was a non-blinded, 2 phase, randomised dietary intervention trial investigating if the rate of weight loss is important in long-term weight maintenance; if physiological adaptations encouraging weight regain are different with different rates of weight loss; if these adaptations reverse with time and if psychological profile can help us choose if slow or rapid weight loss is best suited to a particular psychological profile.
Participants were obese (BMI 30.0 - 45.0 kg/m2) and aged between 18 and 70 years. Following telephone and onsite screening 200 subjects commenced phase 1 of the trial (weight loss phase) and were randomised by strata to either a rapid or gradual weight loss program. During this phase appointments were at the same interval with similar quality of dietary education materials for all subjects. Projected weight-loss graphs were personalised to each participant and utilised at each visit to compare expected and actual weight-loss achieved at each time point. Both the rapid and gradual weight loss group had prescriptions for the same overall energy deficit (105,000 kcal or 430,500 kJ). The rapid weight loss group were asked to accumulate the deficit over 3 months while the gradual weight loss group had to accumulate the same deficit over 9 months. In both treatment groups, participants were instructed to undertake at least 30 minutes a day of mild to moderate intensity exercise (e.g. brisk walk). Participants attended fortnightly for individual consultations with the same qualified dietitian. During these visits, they had anthropometry measurements taken and were given dietary counselling based on their individual needs in order to remain on their projected curve and achieve their target weight of 15% weight loss.
All participants who successfully achieved 15% weight loss in phase 1 were eligible to enter into phase 2 (weight maintenence phase) of the trial. During phase 2 participants followed a weight maintenance diet which was individualised for each participant and similar to the Australian Guidelines for Healthy Eating(Smith A 1998). Individual sessions were conducted with the study dietitian quarterly for the three years following phase I.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 32226 0
Prof Joseph Proietto
Address 32226 0
Department of Medicine- Austin Health
University of Melbourne,
Heidelberg Repatriation Hospital,
300 Waterdale Rd
Heidelberg Heights,
Victoria, 3081
Country 32226 0
Phone 32226 0
+61 3 9496 2250
Fax 32226 0
Email 32226 0
Contact person for public queries
Name 15473 0
Ms Katrina Purcell
Address 15473 0
Department of Medicine- Austin Health
University of Melbourne,
Heidelberg Repatriation Hospital,
300 Waterdale Rd
Heidelberg Heights,
Victoria, 3081
Country 15473 0
Phone 15473 0
+61 39496 4025
Fax 15473 0
Email 15473 0
Contact person for scientific queries
Name 6401 0
Prof Joesph Proietto
Address 6401 0
Department of Medicine- Austin Health
University of Melbourne,
Heidelberg Repatriation Hospital,
300 Waterdale Rd
Heidelberg Heights,
Victoria, 3081
Country 6401 0
Phone 6401 0
+61 3 9496 2250
Fax 6401 0
Email 6401 0

No information has been provided regarding IPD availability
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