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Trial registered on ANZCTR


Registration number
ACTRN12619001035112
Ethics application status
Approved
Date submitted
29/05/2019
Date registered
19/07/2019
Date last updated
21/12/2021
Date data sharing statement initially provided
19/07/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
Developing effective weight loss strategies for shift workers.
Scientific title
Shifting weight in night shift workers with obesity: A randomised parallel intervention study
Secondary ID [1] 298009 0
Nil known
Universal Trial Number (UTN)
U1111-1231-9653
Trial acronym
SWIFt Study
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obesity 312456 0
Metabolic Syndrome 312457 0
Condition category
Condition code
Diet and Nutrition 311005 311005 0 0
Obesity
Metabolic and Endocrine 311006 311006 0 0
Metabolic disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Diet 1: 5:2 Day fasting diet
For five days of the week participants will eat their habitual diet, and on two days of the week (the two ‘fast’ days) they will be required to restrict their energy intake to 2100 kJ/day (female) or 2500 kj (male). These two days will correspond with days that incorporate a day shift. Participants will be provided with study food on each of the energy restriction days.

Diet 2: 5:2 Night fasting diet
For five days of the week participants will eat their usual diet, and on two days of the week (the two ‘fast’ days) they will be required to restrict their energy intake to approximately 2100 kJ/day (female) or 2500 kJ (male). These two days will correspond with days that incorporate a night shift. Participants will be provided with study food on each of the energy restriction days.

Diet 3: 20% Continuous daily Energy Restriction (20% ER)
Based on a participant’s habitual diet (recorded at baseline), usual intake of total energy (kJ) will be reduced by 20%. Participants will be provided with study meals on two days of the week so that the same level of support is provided to each of the three intervention groups.

Each dietary strategy (5:2 Day; 5:2 Night; 20% CER) will be followed for 6 months. Dietitians will deliver the intervention to each individual in person. Following their baseline visit, participants will meet with a dietitian in person every 2 weeks for the first two months (4 visits), and then monthly (4 visits). Following the intervention period, there will be a 12 month maintenance phase during which time participants will be monitored. During the 12 month maintenance phase, participants will receive a phone call from a study dietitian one month into the maintenance phase, and then meet the study dietitian in person at 2 months, 6 months and then at 12 months.

Adherence to dietary interventions will be monitored and assessed through a combination of food diaries, 24 hr diet recalls and checklists.
Intervention code [1] 314236 0
Lifestyle
Intervention code [2] 314237 0
Treatment: Other
Comparator / control treatment
Diet 3 (20% continuous energy restriction) is considered the active control and is the current best practice approach to weight loss in individuals who are overweight.
Control group
Active

Outcomes
Primary outcome [1] 319799 0
Body weight in kg will be assessed using scales
Timepoint [1] 319799 0
0, 3, 6, 12 and 18 months (0 and 6 months primary time points for hypothesis testing)
Primary outcome [2] 320191 0
HOMA-IR
Fasting glucose (clinical chemistry analyser) and fasting insulin (ELIZA)
Timepoint [2] 320191 0
0, 6 months
Secondary outcome [1] 369571 0
Fasting blood glucose
Clinical chemistry analyser
Timepoint [1] 369571 0
0, 6, 18 months
Secondary outcome [2] 370807 0
Fasting lipids
Clinical chemistry analyser,
Timepoint [2] 370807 0
0, 6, 18 months
Secondary outcome [3] 370808 0
Blood pressure will be measured using a sphygmomanometer
Timepoint [3] 370808 0
0, 6, 18 months
Secondary outcome [4] 370809 0
Sleep outcomes will be measured using GENEActiv activity monitors and sleep diaries (exploratory outcome)
Timepoint [4] 370809 0
0, 6, 18 months
Secondary outcome [5] 370810 0
Body composition (fat and fat free mass) using DXA scans.
Timepoint [5] 370810 0
0, 6, 18 months
Secondary outcome [6] 370811 0
Gut microbiome from faecal samples which is an opt in only for Melbourne participants (exploratory outcome)
Timepoint [6] 370811 0
0, 6 months
Secondary outcome [7] 370812 0
Dietary intake and quality assessed using 7 day food diary and 24 hr recall analysis (exploratory outcome)
Timepoint [7] 370812 0
0, 6, 18 months
Secondary outcome [8] 370813 0
Physical activity patterns by wearing GENEActiv activity monitors and questionnaire (IPAQ) (exploratory outcome)
Timepoint [8] 370813 0
0, 6, 18 months
Secondary outcome [9] 370814 0
Quality of Life using AQoL total score and subscales (exploratory outcome)
Timepoint [9] 370814 0
0, 6, 18 months
Secondary outcome [10] 370816 0
Functional mobility Timed up and go test (exploratory outcome)
Timepoint [10] 370816 0
0, 6, 18 months
Secondary outcome [11] 370817 0
Waist circumference using an anthropometric retractable measuring tape
Timepoint [11] 370817 0
0, 6, 18 months
Secondary outcome [12] 370819 0
Depression scale measured by the DASS-21 questionnaire (exploratory outcome)
Timepoint [12] 370819 0
0, 6, 18 months
Secondary outcome [13] 370820 0
Fasting insulin levels as analysed using ELISA
Timepoint [13] 370820 0
0, 6, 18 months
Secondary outcome [14] 370823 0
Survey of shiftworkers (exploratory outcome)
Timepoint [14] 370823 0
0, 6, 18 months
Secondary outcome [15] 371122 0
Anxiety scale measured by the DASS-21 questionnaire (exploratory outcome)
Timepoint [15] 371122 0
0, 6 and 18 months post enrolment
Secondary outcome [16] 371123 0
Stress scale measured by the DASS-21 questionnaire (exploratory outcome)
Timepoint [16] 371123 0
0, 6 and 18 months post enrolment
Secondary outcome [17] 371152 0
HOMA-IR from fasting blood samples
Timepoint [17] 371152 0
18 months post enrolment
Secondary outcome [18] 372315 0
Time to drop out (days) will be assessed by date of last contact i.e last recorded weight, last visit, official withdrawal
Timepoint [18] 372315 0
Anytime after baseline (days)
Secondary outcome [19] 404446 0
HbA1C from whole blood
Timepoint [19] 404446 0
0, 6 and 18 months post enrolment

Eligibility
Key inclusion criteria
For Caucasian, BMI greater than or equal to 28 kg/m2
For Asians, BMI greater than or equal to 26 kg/m2
Weight loss in the past 3 months with weight change of no more than 5kg
Minimum age
25 Years
Maximum age
65 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
• Within healthy weight range
• Individuals that do not work night shift i.e., day shift only workers are excluded
• Have a genetic condition that impacts weight, appetite and/or metabolic measures (e.g., Prada Willi)
• Diagnosed with a medical condition (e.g., Inflammatory bowel disease, Diabetes, Polycystic Ovarian Syndrome, CVD)
• Pregnancy / breastfeeding
• Dietary allergies / intolerance preventing consumption of provided study-meals
• Prescription medication and over-the-counter-medication that affect metabolic outcomes/measures
• Require drug-therapy (e.g., Insulin, Levothyroxine, anti-depressants, statins) that impacts weight, appetite and or metabolic measures. Assess on a case-by-case basis.
• Failure to satisfy the investigator regarding suitability to participate for any other reason
• Had previous weight loss surgery
• Unwilling or unable to provide informed consent
• Pregnant, planning a pregnancy or breastfeeding, and not prepared to do a pregnancy test
• Not able to complete a 6-month weight loss intervention and a 12-month maintenance follow-up
• Dietary allergies or dietary restrictions that prevent consumption of provided study foods
• Taking extended leave from work in the next 6 months

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation concealment to be maintained by use of a randomisation procedure to be performed centrally by an independent body, The NHMRC Clinical Trials Centre
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation to be performed by adaptive methods, in particular minimisation stratified by Site (Monash, Uni. SA), Gender (male, female) and age
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?


The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
N/A
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
The aim of this study was to compare weight loss in night shift workers randomised to three diets. There is currently insufficient information to enable predictions about which diet will perform best, however this study will rank the three diets from most successful to least successful based on absolute amount of weight loss achieved at 6 months.

Our primary hypothesis is that there will be weight loss in all three groups during the treatment phase. To test this hypothesis, mixed effects models will specify a dependent variable of weight (kg) with a predictor variable of Time (baseline, 6 months), controlling for site (Melbourne, Adelaide), and a random effect of subject on the intercept, allowing participants to vary according to individual baseline levels, as well as tracking progress over time, appropriately accounting for serial correlation. We will undertake intention-to-treat and per protocol analyses. The primary effects of interest are the hypothesised change over time in each group. Power calculations are based on previous research, which found a small-medium within-subjects effect for a 14-week workplace weight loss program (f=0.16; [1]). Using this as a minimum expected amount of weight loss in a given study group over a six-month time period, (accounting for serial correlation between baseline and 6 months) at the end of the treatment phase we would require 93 participants (a=0.05, 1-ß=0.8), accounting for an expected 27% drop-out [1], we need to randomise 120 participants into each diet group. Therefore, we need a total of 360 participants.

Descriptive analyses will quantify the effect size of the weight loss in each diet group. We will calculate point estimates and their variability (bootstrapping for 95% Confidence Intervals). These will be calculated for the active phase, and for the maintenance phase (18 months).

A secondary hypothesis is that there will be a differential effect of the diets across time on HOMA-IR (insulin resistance). Based on previous research suggesting the potential metabolic benefits of avoiding food consumption during night time hours (e.g. [2] Grant et al., 2017), we hypothesise that the 5:2 Nighttime fasting group will display an improvement in metabolism (as indicated by HOMA-IR) relative to the other diet groups. To test this hypothesis, mixed effects models will specify a dependent variable of HOMA-IR. Models will specify predictor variables of Group (20% ER, 5:2 Day time fasting, and 5:2 Night time fasting), Time (baseline, 6 months), and Group*Time, with a random effect of subject on the intercept. The primary effect of interest is the Group*Time interaction effect. Power calculations are based on previous research, which found effect sizes for differences in night and day shift workers in HOMA-IR that ranged from small-medium (f=0.14; [3]), to medium-large (f=0.33; [4]). Conservatively powering for a small-medium interaction effect, we require 111 participants per group (a=0.05, 1-ß=0.8), and accounting for an expected 27% drop-out [1], we need to recruit a total of 423 participants.

Additional analyses will examine changes in HOMA-IR in each of the groups during the maintenance phase (18 months). Mixed effects models will specify a dependent variable of HOMA-IR and predictor variables of Group (20% ER, 5:2 Day time fasting, and 5:2 Night time fasting), Time (6 months, 12 months, 18 months), and Group*Time, with a random effect of subject on the intercept.

In order to make sure that there is sufficient power to adequately test all of study hypotheses, we require the largest sample size estimate from the above calculations. Therefore, to detect all the effects of interest, 141 participants per group (Total = 423) will be recruited over the two sites.

[1] Morgan, P. J., Collins, C. E., Plotnikoff, R. C., Cook, A. T., Berthon, B., Mitchell, S., & Callister, R. (2011). Efficacy of a workplace-based weight loss program for overweight male shift workers: The Workplace POWER (Preventing Obesity Without Eating like a Rabbit) randomized controlled trial. Preventive medicine, 52(5), 317-325.
[2] Grant, C. L., Coates, A. M., Dorrian, J., Kennaway, D. J., Wittert, G. A., Heilbronn, L. K., ... & Banks, S. (2017). Timing of food intake during simulated night shift impacts glucose metabolism: A controlled study. Chronobiology international, 34(8), 1003-1013.
[3] Padilha, H. G., Crispim, C. A., Zimberg, I. Z., Folkard, S., Tufik, S., & de Mello, M. T. (2010). Metabolic responses on the early shift. Chronobiology international, 27(5), 1080-1092.
[4] Akour, A., Farha, R. A., Alefishat, E., Kasabri, V., Bulatova, N., & Naffa, R. (2017). Insulin resistance and levels of cardiovascular biomarkers in night-shift workers. Sleep and Biological Rhythms, 15(4), 283-290.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
16/09/2019
Actual
19/09/2019
Date of last participant enrolment
Anticipated
31/01/2022
Actual
Date of last data collection
Anticipated
31/07/2023
Actual
Sample size
Target
423
Accrual to date
148
Final
Recruitment in Australia
Recruitment state(s)
SA,VIC
Recruitment postcode(s) [1] 27177 0
5000 - Adelaide
Recruitment postcode(s) [2] 27178 0
3168 - Notting Hill

Funding & Sponsors
Funding source category [1] 302533 0
Government body
Name [1] 302533 0
NHMRC (National Health and Medical Research Council)
Country [1] 302533 0
Australia
Primary sponsor type
Individual
Name
A/Professor Maxine Bonham
Address
Be Active Sleep Eat (BASE) Facility
Department of Nutrition, Dietetics and Food,
Monash University
Level 1,, 264 Ferntree Gully Road, Notting Hill,
Victoria 3168
Country
Australia
Secondary sponsor category [1] 302444 0
Individual
Name [1] 302444 0
Professor Siobhan Banks
Address [1] 302444 0
School of Psychology, Social Work and Social Policy
University of South Australia Magill Campus
St Bernards Road, Magill
Adelaide 5072,
South Australia,
Country [1] 302444 0
Australia
Secondary sponsor category [2] 302856 0
Individual
Name [2] 302856 0
A/Professor Alison Coates
Address [2] 302856 0
Alliance for Research in Exercise, Nutrition and Activity (ARENA),
School of Health Sciences,
University of South Australia,, City East Campus,
108 North Terrace,
Adelaide SA 5001
South Australia.
Country [2] 302856 0
Australia
Secondary sponsor category [3] 302857 0
Individual
Name [3] 302857 0
A/Professor Jill Dorrian
Address [3] 302857 0
School of Psychology, Social Work and Social Policy
University of South Australia Magill Campus
St Bernards Road, Magill
Adelaide 5072,
South Australia,
Country [3] 302857 0
Australia
Secondary sponsor category [4] 302858 0
Individual
Name [4] 302858 0
Dr Nicole Kellow
Address [4] 302858 0
Be Active Sleep Eat (BASE) Facility
Department of Nutrition, Dietetics and Food,
Monash University
Level 1,, 264 Ferntree Gully Road, Notting Hill,
Victoria 3168
Country [4] 302858 0
Australia
Secondary sponsor category [5] 302859 0
Individual
Name [5] 302859 0
Dr Catherine Huggins
Address [5] 302859 0
Be Active Sleep Eat (BASE) Facility
Department of Nutrition, Dietetics and Food,
Monash University
Level 1,, 264 Ferntree Gully Road, Notting Hill,
Victoria 3168
Country [5] 302859 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 303183 0
Monash University Human Research Ethics Committee
Ethics committee address [1] 303183 0
Monash Research Office, 26 Sports Walk, Monash University, Wellington Road, Clayton, Vic 3800
Ethics committee country [1] 303183 0
Australia
Date submitted for ethics approval [1] 303183 0
03/04/2019
Approval date [1] 303183 0
04/06/2019
Ethics approval number [1] 303183 0
18426

Summary
Brief summary
For shift workers there is an increased risk of 23% of developing obesity and 44% of developing type 2 diabetes. There are currently 1.5 million Australians (~16% of workforce population) who are at risk. The risk of obesity and type 2 diabetes in this population group do not appear to be related solely to overall energy intake. Previous research has shown that meal timing i.e. eating late into the night, as is common among shift worker, is associated with metabolic complications such as impaired glucose tolerance and insulin resistance, potentially contributing to weight gain. However, there is currently a lack of evidence to identify effective weight loss strategies in shift workers with obesity. We aim to compare three weight loss regimens in a population of shift workers to identify weight loss strategies that will a) result in successful weight loss and b) be flexible to the demanding lifestyles of the shift working population. This six month dietary intervention study will compare continuous energy restriction (diet 1) with intermittent fasting (5:2). The two fast days will either be days that participants work a day shift (diet 2) or days that participants work night shift (diet 3). The study hypothesises that each of the dietary interventions will be effective at inducing weight loss but there will be a differential effect of the diets across time on HOMA-IR (a measure of insulin resistance).
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 92774 0
A/Prof Maxine Bonham
Address 92774 0
Department of Nutriton, Dietetics and Food
Level 1, 264 Ferntree Gully Road, Notting Hill,
Monash University,
Victoria, 3168
Country 92774 0
Australia
Phone 92774 0
+61 3 9902 4272
Fax 92774 0
Email 92774 0
[email protected]
Contact person for public queries
Name 92775 0
Maxine Bonham
Address 92775 0
Department of Nutriton, Dietetics and Food
Level 1, 264 Ferntree Gully Road, Notting Hill,
Monash University,
Victoria, 3168
Country 92775 0
Australia
Phone 92775 0
+61 3 9902 4272
Fax 92775 0
Email 92775 0
[email protected]
Contact person for scientific queries
Name 92776 0
Maxine Bonham
Address 92776 0
Department of Nutriton, Dietetics and Food
Level 1, 264 Ferntree Gully Road, Notting Hill,
Monash University,
Victoria, 3168
Country 92776 0
Australia
Phone 92776 0
+61 3 9902 4272
Fax 92776 0
Email 92776 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
After de-identification; individual participant data underlying published results only
When will data be available (start and end dates)?
Beginning 12 months and ending 5 years following main results publication
Available to whom?
Only researchers who provide a methodologically sound proposal, case-by-case basis at the discretion of Primary Sponsor
Available for what types of analyses?
Any purpose that has ethical approval and meets the approval of the primary sponsor
How or where can data be obtained?
Access subject to approvals by Principal Investigator, requirement to sign data access agreement


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
SourceTitleYear of PublicationDOI
EmbaseStudy protocol for the Shifting Weight using Intermittent Fasting in night shift workers (SWIFt) study: A three-arm randomised controlled trial comparing three weight loss strategies in night shift workers with obesity.2022https://dx.doi.org/10.1136/bmjopen-2021-060520
EmbaseEvaluation of the "Shifting Weight using Intermittent Fasting in night-shift workers" weight loss interventions: a mixed-methods protocol.2023https://dx.doi.org/10.3389/fpubh.2023.1228628
N.B. These documents automatically identified may not have been verified by the study sponsor.