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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
The SWIFT trial - Supporting weight loss in adults with whole-food diets, intermittent fasting and high-intensity interval training
Scientific title
The effect of different support strategies on weight loss, indicators of health, and lifestyle behaviours in overweight men and women
Secondary ID [1] 285689 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 293545 0
Condition category
Condition code
Diet and Nutrition 293820 293820 0 0
Public Health 293821 293821 0 0
Other public health

Study type
Description of intervention(s) / exposure
Participants will be randomised to one of 5 intervention groups for a 12 month period followed by a further 12 month follow-up: 1) control, 2) brief support - will meet with researchers once a month for 5-10 minutes to be weighed and have a brief discussion about progress and to address any concerns, 3) self-weighing - will be asked to weigh themselves at the same time every day and enter weight into our online database, email feedback on progress will be provided once a month, 4) My Fitness Pal - participants will be shown how to use this online/mobile app which allows them to track their dietary intake. Participants will use the app daily for the first month and then one week per month for 11 months, 5) Hunger training - participants will be taught how to eat to hunger and satiety using a combination of fingerprick blood glucose testing and awareness of hunger types. Participants will meet face-to-face with a dietitian for a 2-hour training session on day 0, followed by a quick phone call to assess progress on day 2 and a 30-60 minute face-to-face session on day 14. Participants will be monitoring their blood glucose and using the booklet daily for the first fortnight, after which blood glucose monitoring becomes optional. They will continue to use the booklet daily for the second fortnight, and then one week every month for the remaining 11 months.

While participants are randomised to a certain support group and thus have no choice in this, they are allowed to choose which diet and exercise regime they would like to follow over the course of the 24 month study (including group 1 - the control group). Potential dietary approaches they can choose from include the Mediterranean diet, a modified Paleo approach (allows limited legumes and dairy) and intermittent fasting (5:2 approach). The mediterranean diet approach encourages wholegrains, fresh fruit and vegetables but limits red meat, sugar and saturated fat. The modified paleo (whole-food diet) approach encourages consumption of minimally processed foods with an emphasis on plant foods and animal proteins, but limiting sugar or grain-based foods. Small amounts of dairy and legumes are permitted if wanted by participants. The intermittent fasting approach outlines restriction of energy intake on 2 days a week to a quarter of normal intake. All dietary interventions are given with an extensive printed resource with recipes and guidance, as well as a half hour session with one of the researchers to answer questions.
Potential exercise approaches include current recommendations, or a home-based high-intensity interval training (HIIT) programme. Participants choosing current recommendations discuss their choice of exercise type with a researcher and HIIT participants undergo a medical assessment and a one-off HIIT session training with heart rate monitoring.
Intervention code [1] 290629 0
Intervention code [2] 290834 0
Treatment: Other
Intervention code [3] 290835 0
Comparator / control treatment
Control participants will receive the dietary and exercise intervention as outlined earlier but no additional support. They will undertake all outcome assessments as for the other participants.
Control group

Primary outcome [1] 293605 0
Body weight will be measured in duplicate using electronic digital scales
Timepoint [1] 293605 0
0, 6, 12, 24 months
Secondary outcome [1] 311460 0
Percentage body fat by DXA
Timepoint [1] 311460 0
0, 12 months
Secondary outcome [2] 311461 0
Intuitive Eating Scale
Timepoint [2] 311461 0
0, 12, 24 months
Secondary outcome [3] 311462 0
Disordered eating questionnaire - EDE-Q
Timepoint [3] 311462 0
0, 12, 24 months
Secondary outcome [4] 311881 0
Physical activity by 7-day accelerometry (Actigraph)
Timepoint [4] 311881 0
0, 12, 24 months
Secondary outcome [5] 311992 0
Adherence to support strategies:
Brief support - by electronic records of attendance at monthly sessions
Self-weighing - participants enter weight online each day onto a specialised database which is checked weekly by researchers for completion.
MyFitnessPal - Data are collected by the app, which the participant shares with the researchers by setting their food diary as "public"
Hunger training - from participant completed diaries which outline when they ate, what their blood glucose was, and what their hunger ratings were before eating
Timepoint [5] 311992 0
Brief support monthly from 0-12 months
Self-weighing daily from 0-12 months
MyFitnessPal daily for month 1, then one week in each of months 2-12
Hunger training daily for month 1, then one week in each of months 2-12
Secondary outcome [6] 311993 0
Adherence to diet and exercise interventions
Adherence to the dietary regimes will be measured using the 3-day diet records. Those choosing to follow intermittent fasting will complete a 4-day diet record (2 fasting, 2 non-fasting days) at 6, 12 and 24 months. Adherence to the exercise regime will be measured by the accelerometers. In addition, HIIT participants will wear a Polar RC3 GPS heart rate monitor during all home HIIT sessions for a one-week period at baseline, 3, 6, 9 and 12 months to evaluate intensity attained during the sessions.
Timepoint [6] 311993 0
Diet records at 0, 6, 12 and 24 months
Accelerometry at 0, 12, 24 months
Heart rate monitoring (for HIIT participants only) for a one-week period at 0, 3, 6, 9, 12, and 24 months

Key inclusion criteria
Body mass index greater than 27 and otherwise healthy
Minimum age
18 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Pre-existing disease (diabetes, cancer, cardiovascular disease requiring medical management), endocrine disorders, systemic inflammatory diseases, or history of serious medical problems
Pregnant or planning to become pregnant in the next two years
Musculoskeletal disorders preventing exercise
Fasting blood glucose greater than 7 mmol/L (as not suitable for hunger training)
Systolic blood pressure greater than 160 mmHg or diastolic blood pressure greater than 100mmHg (as require medical intervention)

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 will complete an initial eligibility questionnaire online. If eligible, researchers will contact them, establish their willingness to continue participation and schedule the participant for baseline measurements. After informed consent has been obtained, additional baseline measurements are undertaken. One a participant has been confirmed eligible and has completed all baseline assessments, they choose which diet and exercise regime they would like to try. Randomisation to support condition will occur using sequentially numbered opaque sealed envelopes prepared by the statistician. The participants will be stratified by sex and random length blocks will be used to allocate the treatment. Participants will then be booked into their first intervention session.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

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
SWIFT is a 24-month RCT involving a 12-month intervention with a follow-up at 24 months. Weight (primary outcome) will be measured at 0, 6, 12 and 24 months as will most of the secondary outcomes, with the exception of the accelerometers and some questionnaires (0, 12 and 24 months only).

Based on a standard deviation (SD) for baseline weight of 15kg, and a correlation between repeat measures of r = 0.90 (obtained from our previous studies involving similar populations), our study has 90% power using a two-sided 5% level of significance to detect a clinically important difference in change in body weight of 4kg between any pair of groups with 42 participants per group. Thus we will recruit 250 participants in total across the five groups which allows for 15% drop-out/unusable data. Fifty per group at baseline also provides 80% power to detect differences of 5cm in waist circumference (baseline SD 12, r = 0.80).

The primary analysis will follow modified intention-to-treat principles (using all available data) and will compare the outcomes resulting from the five different support strategies (RCT analysis). Linear mixed models will be used to model outcomes at 6, 12 and 24 months after adjusting for baseline values. Standard mixed model diagnostics will be performed.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 6483 0
New Zealand
State/province [1] 6483 0

Funding & Sponsors
Funding source category [1] 290256 0
Name [1] 290256 0
University of Otago
Address [1] 290256 0
PO Box 56
Dunedin 9054
New Zealand
Country [1] 290256 0
New Zealand
Funding source category [2] 290424 0
Name [2] 290424 0
Private bequest
Address [2] 290424 0
Edgar Diabetes and Obesity Research Centre
PO Box 56
Dunedin 9054
Country [2] 290424 0
New Zealand
Primary sponsor type
University of Otago
PO Box 56
Dunedin 9054
New Zealand
Secondary sponsor category [1] 289138 0
Name [1] 289138 0
Address [1] 289138 0
Country [1] 289138 0

Ethics approval
Ethics application status
Ethics committee name [1] 291956 0
University of Otago Ethics Committee
Ethics committee address [1] 291956 0
University of Otago
PO Box 56
Dunedin 9054
Ethics committee country [1] 291956 0
New Zealand
Date submitted for ethics approval [1] 291956 0
Approval date [1] 291956 0
Ethics approval number [1] 291956 0

Brief summary
Although people argue over whether there is a "best" diet for weight loss, it is becoming increasingly apparent that a variety of diets are healthy and appropriate. What is more important is determining how best we can support people to adhere to appropriate dietary change over the long-term. This project will let people choose from a selection of appropriate dietary approaches that they would like to follow (a paleo-type diet, intermittent fasting, or a mediterranean diet) as well as choosing whether to try high-intensity interval training or current recommendations, then randomise them to one of five different ways of supporting them to make those changes to their diet/activity over a two-year period.
Trial website
Trial related presentations / publications
Taylor RW et al. Determining how best to support overweight adults to adhere to lifestyle change: protocol for the SWIFT study. BMC Public Health 2015;15:861.
Jospe MR et al. Adherence to hunger training using blood glucose monitoring: a feasibility study. Nutr Metab 2015;12:22
Jospe M et al. The effect of different types of monitoring strategies on weight loss: a randomised controlled trial. Obesity 2017;25(9):1490–1498.
Public notes

Principal investigator
Name 52846 0
A/Prof Rachael Taylor
Address 52846 0
Department of Medicine
University of Otago
PO Box 56
Dunedin 9054
Country 52846 0
New Zealand
Phone 52846 0
+64 3 470 9180
Fax 52846 0
Email 52846 0
Contact person for public queries
Name 52847 0
Ms Jenny McArthur
Address 52847 0
Department of Medicine
University of Otago
PO Box 56
Dunedin 9054
Country 52847 0
New Zealand
Phone 52847 0
+64 3 479 5953
Fax 52847 0
Email 52847 0
Contact person for scientific queries
Name 52848 0
A/Prof Rachael Taylor
Address 52848 0
Department of Medicine
University of Otago
PO Box 56
Dunedin 9054
Country 52848 0
New Zealand
Phone 52848 0
+64 3 470 9180
Fax 52848 0
Email 52848 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