COVID-19 studies are our top priority.

For new and updated trial submissions, we are processing trials as quickly as possible and appreciate your patience. We recommend submitting your trial for registration at the same time as ethics submission.

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
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
The effect of intermittent energy restriction (5:2 diet) on weight loss and risk of type 2 diabetes in women who have had gestational diabetes.
Scientific title
The effect of intermittent energy restriction on weight loss and diabetes risk markers in women who have had gestational diabetes.
Secondary ID [1] 293137 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 diabetes 305108 0
Gestational diabetes 305109 0
overweight or obese 305110 0
Condition category
Condition code
Diet and Nutrition 304419 304419 0 0
Metabolic and Endocrine 304420 304420 0 0
Reproductive Health and Childbirth 304444 304444 0 0
Fetal medicine and complications of pregnancy

Study type
Description of intervention(s) / exposure
A 12 month randomised control study will be conducted. Participants randomised to the intermittent energy restriction (IER) group will be required to follow a very low energy diet of 2100kJ (500kCal) for two days per week and allowed ad libitum eating for the other five days per week. They may choose any days of the week for their ‘fasting’ days based on their individual preferences and will be encouraged to eat sensibly on their non-fasting days. Participants will receive education and written information developed by the study Dietitian on how to adhere to the fasting days, information on calorie content of foods and sample meal plans for the 2100kJ days also developed by the study Dietitian. Women who are breastfeeding will be allowed extra calorie allowance of up to 2100kJ per day to allow for the energy cost of human milk production and the study dietitian will advise protein intake of 67g per day, adequate hydration and advise that fasting days must not be consecutive. Additionally, breastfeeding mothers will be required to weigh themselves weekly (scales will be provided) to ensure that weight loss does not exceed 0.5kg per week. These participants will have fortnightly follow up with the study Dietitian via phone call, email or university visit if needed for the first 3 months then a minimum of monthly follow up through email, phone call or university visit while they continue to breastfeed. Phone calls or visits would take between five and fifteen minutes.
Participants will attend the clinic on 7 occasions over the 12 months (baseline, 1, 2 3,6, 9 and 12 months). At each visit they will be seen by the study dietitian who will check their compliance with the diet through diet checklists, weigh the participant and answer any questions. Weight will be taken at every visit. CSIRO Healthy Eating Score survey and a physical activity survey (Active Australia survey) and a sleep quality questionnaire (Pittsburgh Sleep Quality index) will be administered at baseline, 3, 6 and 12 months. Fasting blood samples will be taken on three occasions (baseline, 3 and 12 months) and will test fasting glucose, fasting insulin. HbA1C and fasting glucose will be measured by finger prick analysis at baseline, 3, and 12 months . A 2-hr oral glucose tolerance test (OGTT) will also be administered at baseline and 12 months, this will be done by using whole capillary blood via finger prick analysis with a glucometer.
Visits to the clinic at baseline and 12 months will take between 2.25 and 2.5 hours due to the 2 hour OGTT. All other visits (1,2,3,6 and 9 months) will take 15-20 minutes.
Women who achieve a weight loss of 7% of their body weight or reach a BMI of 21kg/m2 will be asked to maintain their body weight and be given advice on how to do this. Participants will be encouraged to meet physical activity recommendations of 30 minutes moderate physical activity per day on most days of the week.
Intervention code [1] 299387 0
Intervention code [2] 299396 0
Intervention code [3] 299397 0
Treatment: Other
Comparator / control treatment
Participants will follow a continuous energy restriction diet (CER) over the 12 month study. They will be allowed 6000 kJ (1500kCal) each day. They will be given education on how to adhere to their diet, verbal and written information on the calorie content of various foods and sample meal plans. They will be encouraged to consume a healthy diet to make up their daily calorie allowance and limit consumption of discretionary foods and drinks. The diet materials are developed by the study Dietitian and based on the CSIRO Total Wellbeing Diet. Breastfeeding women will be allowed up to an extra 2100kJ per day as per the IER group and will be required to weigh themselves weekly to ensure weight loss does not exceed 0.5kg per week. All visits, tests and procedures will be the same for the CER group as the IER group for both breastfeeding and non breastfeeding women.
Control group

Primary outcome [1] 303657 0
Weight loss measured on digital scales.
Timepoint [1] 303657 0
Baseline, 1,2,3, 6, 9 and 12 months (12 months primary timepoint)
Secondary outcome [1] 339801 0
2 hour glucose tolerance measured from a fasting 2-hr 75g oral glucose tolerance test taken by capillary whole blood finger-prick analysis at 0, 60 and 120 minute
Timepoint [1] 339801 0
Baseline, 12 months
Secondary outcome [2] 339802 0
HbA1C measured using a HbA1c point of care machine.
Timepoint [2] 339802 0
Baseline, 3 and 12 months
Secondary outcome [3] 339804 0
Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) calculated from fasting glucose and fasting insulin blood sample tests.
Timepoint [3] 339804 0
Baseline, 3 and 12 months
Secondary outcome [4] 339806 0
Change in quality of dietary intake measured from the CSIRO Healthy Diet Score online survey
Timepoint [4] 339806 0
Baseline, 3, 6 and 12 months
Secondary outcome [5] 339851 0
Fasting glucose taken from blood sample and capillary whole blood
Timepoint [5] 339851 0
Baseline, 3 and 12 months
Secondary outcome [6] 339852 0
Fasting insulin taken from venous blood sample
Timepoint [6] 339852 0
Baseline, 3 and 12 months
Secondary outcome [7] 393339 0
Change in Body Mass Index
BMI was calculated from height and weight using the equation BMI=[weight(kg) / height(m2)].
Height was measured at the baseline visit without shoes on using a wall-mounted stadiometer and recorded to the nearest 0.1cm. Body weight was measured at each visit in light clothing without shoes using calibrated electronic digital scales and recorded to the nearest 0.1kg.
Timepoint [7] 393339 0
0, 3 and 12 months

Key inclusion criteria
- Age 18 years or over
- Diagnosed with gestational diabetes (GDM) by a medical professional during a pregnancy
- BMI greater than or equal to 25kg/m2
- Not taking any diabetes medication including metformin
Minimum age
18 Years
Maximum age
No limit
Can healthy volunteers participate?
Key exclusion criteria
Diagnosed with diabetes either prior to their GDM pregnancy or have developed diabetes since their GDM pregnancy.
- Pregnant or less than 12 weeks post partum
- Previous surgery for weight loss
- Participating in any other diets or clinical studies involving medical or lifestyle interventions
- Have been following the 5:2 diet in the last 3 months
- non-English speaking
-Current diagnosis of an eating disorder
- Any other significant illness or disease

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Following initial contact with the university potential subjects will be screened and randomly allocated to one of the arms of the study. Participants will be stratified according to years since GDM (=5 years and > 5 years) and BMI (<30kg/m2 and =30kg/m2). . A random number block randomization will be used. Allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Computerised random balanced number sequence generator (
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
A non inferiority power calculation was conducted to determine the sample size needed for the study to identify if a difference does exist between the intervention and control groups using weight loss as the primary outcome. With 80% power, significance set at 5% and allowing for 50% drop out rate 141 participants would be needed.

Data tabulation and descriptive analysis of all independent and dependent variables will be conducted. Summary statistics, such as means, variances, and standard deviations, will be reported for each variable. Data will be tested for normal distribution using Q-Q plots and Kolomogorov-Smivov tests. Pearson’s chi-squared tests for categorical variables, and independent t-tests or Wilcoxon rank sum for continuous variables will compare differences between intervention and control groups at baseline and over time for weight, BMI, fasting glucose, 2-hr glucose, HbA1C, insulin resistance and HOMA-IR.. Participants will be stratified according to BMI and for the intervention studies an intention-to-treat method of analysis will be adhered to. Statistical significance will be set to p<0.05.

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)

Funding & Sponsors
Funding source category [1] 297762 0
Name [1] 297762 0
University of South Australia
Address [1] 297762 0
School of Pharmacy and Medical Sciences
GPO Box 2471 Adelaide SA 5000
Country [1] 297762 0
Primary sponsor type
University of South Australia
School of Pharmacy and Medical Sciences
GPO Box 2471 Adelaide SA 5000
Secondary sponsor category [1] 296803 0
Name [1] 296803 0
Address [1] 296803 0
Country [1] 296803 0

Ethics approval
Ethics application status
Ethics committee name [1] 298825 0
University of South Australia Human Ethics Committee
Ethics committee address [1] 298825 0
GPO Box 2471, Adelaide SA 5001
Ethics committee country [1] 298825 0
Date submitted for ethics approval [1] 298825 0
Approval date [1] 298825 0
Ethics approval number [1] 298825 0

Brief summary
In 2015 at least 10.9% of pregnant women in Australia were diagnosed with gestational diabetes (GDM) (1, 2). GDM creates risk of complications to both mother and baby during pregnancy, labour and delivery, and although GDM usually disappears shortly after birth, the mother remains at high risk for developing Type 2 Diabetes (T2DM) in the future (3). The health risks and complications associated with T2DM are well known and include development of other chronic diseases including cardiovascular disease (CVD), heart attack, stroke and kidney disease making diabetes a major health concern in Australia and globally (4). Lifestyle interventions involving diet and/or exercise that result in weight loss can reduce the risk of developing T2DM (5), however research has shown weight loss is not easily achieved or maintained (6-8). Keeping women engaged in a weight loss program can be difficult when they have a baby or young children to care for given the time constraints and lifestyle adjustments associated with looking after their children (9). Intermittent Energy Restriction (IER) is a form of calorie restriction which requires periods of severe calorie restriction or fasting) followed by periods of non-restricted eating each week. Previous research shows IER can result in weight loss at a comparable rate to daily energy restriction (10, 11).
This study will test if the IER diet strategy commonly known as ‘the 5:2 diet’ provides a suitable regime for women with a history of GDM who have a young family at home by creating less burden and interruption to daily life by restricting energy intake for short periods and advising usual but not excessive eating the rest of the week. This will be the first study that examines an IER pattern for weight loss and T2DM prevention following GDM. Results from this PhD have the potential to benefit Australian women and families by improving their health and potentially reducing the financial burden associated with diabetes to individuals and the community.

1. National Diabetes Services Scheme. NDSS Data Snapshots December 2015 2015 [20/06/2017]. Available from:
2. Australian Bureau of Statistics. 3301.0 - Births, Australia, 2015, Summary of Statistics for Australia 2016 [Available from:
3. Bellamy L, Casas JP, Hingorani AD, Williams D. Type 2 diabetes mellitus after gestational diabetes: a systematic review and meta-analysis. Lancet (London, England). 2009;373(9677):1773-9.
4. Baker IDI Heart & Diabetes Institute, Diabetes Australia, Juvenile Diabetes Research Foundation. Diabetes: the silent pandemic and its impact on Australia. 2012:27.
5. Ratner RE, Christophi CA, Metzger BE, Dabelea D, Bennett PH, Pi-Sunyer X, et al. Prevention of diabetes in women with a history of gestational diabetes: effects of metformin and lifestyle interventions. The Journal of clinical endocrinology and metabolism. 2008;93(12):4774-9.
6. Morton S, Kirkwood S, Thangaratinam S. Interventions to modify the progression to type 2 diabetes mellitus in women with gestational diabetes: a systematic review of literature. Current opinion in obstetrics & gynecology. 2014;26(6):476-86.
7. Guo J, Chen J-L, Whittemore R, Whitaker E. Postpartum lifestyle interventions to prevent type 2 diabetes among women with history of gestational diabetes: A systematic review of randomized clinical trials. J Women's Health. 2016;25(1):38-49.
8. Peacock AS, Bogossian F, McIntyre HD, Wilkinson S. A review of interventions to prevent type 2 diabetes after gestational diabetes. Journal of the Australian College of Midwives. 2014;27(4):e7-e15.
9. Amorim AR, Linne YM, Lourenco PM. Diet or exercise, or both, for weight reduction in women after childbirth. Cochrane Database Syst Rev. 2007(3):Cd005627.
10. Davis CS, Clarke RE, Coulter SN, Rounsefell KN, Walker RE, Rauch CE, et al. Intermittent energy restriction and weight loss: a systematic review. Eur J Clin Nutr. 2016;70(3):292-9.
11. Headland M, Clifton PM, Carter S, Keogh JB. Weight-loss outcomes: A systematic review and meta-analysis of intermittent energy restriction trials lasting a minimum of 6 months. Nutrients. 2016;8(6):08.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 78354 0
Mrs Kristy Gray
Address 78354 0
University of South Australia
GPO Box 2471, Adelaide SA 5001
Country 78354 0
Phone 78354 0
Fax 78354 0
Email 78354 0
Contact person for public queries
Name 78355 0
A/Prof Jennifer Keogh
Address 78355 0
School of Pharmacy and Medical Sciences, University of South Australia
Office: P1-23 Playford Building City East Campus
Postal address: GPO Box 2471 Adelaide SA 5000
Country 78355 0
Phone 78355 0
+61 8 83022579
Fax 78355 0
+61 8 8302 2389
Email 78355 0
Contact person for scientific queries
Name 78356 0
A/Prof Jennifer Keogh
Address 78356 0
School of Pharmacy and Medical Sciences, University of South Australia
Office: P1-23 Playford Building City East Campus
Postal address: GPO Box 2471 Adelaide SA 5000
Country 78356 0
Phone 78356 0
+61 8 83022579
Fax 78356 0
+61 8 8302 2389
Email 78356 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
No IPD data will be available for this trial as this was not approved by ethics.
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