Study 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

Michelle Rogers; Alison Coates; Catherine E Huggins; Jillian Dorrian; Angela B Clark; Corinne Davis; Gloria Kw Leung; Rochelle Davis; Yan Yin Phoi; Nicole J Kellow; Marina Iacovou; Crystal L Yates; Siobhan Banks; Tracey L Sletten; Maxine P Bonham

doi:10.1136/bmjopen-2021-060520

Study 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

BMJ Open. 2022 Apr 26;12(4):e060520. doi: 10.1136/bmjopen-2021-060520.

Authors

Michelle Rogers^{1

2}, Alison Coates^{2

3}, Catherine E Huggins⁴, Jillian Dorrian¹, Angela B Clark⁵, Corinne Davis⁵, Gloria Kw Leung⁵, Rochelle Davis⁵, Yan Yin Phoi^{2

3}, Nicole J Kellow⁵, Marina Iacovou^{6

7}, Crystal L Yates^{1

8}, Siobhan Banks^{1

8}, Tracey L Sletten^{5

9}, Maxine P Bonham¹⁰

Affiliations

¹ UniSA Justice & Society, University of South Australia, Adelaide, South Australia, Australia.
² Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, South Australia, Australia.
³ Allied Health and Human Performance, University of South Australia, Adelaide, South Australia, Australia.
⁴ Institute for Health Transformation, Deakin University, Burwood, Victoria, Australia.
⁵ Department of Nutrition, Dietetics and Food, Monash University, Notting Hill, Victoria, Australia.
⁶ Centre of Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia.
⁷ Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia.
⁸ Behaviour-Brain-Body Research Centre, University of South Australia, Adelaide, South Australia, Australia.
⁹ Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Notting Hill, Victoria, Australia.
¹⁰ Department of Nutrition, Dietetics and Food, Monash University, Notting Hill, Victoria, Australia maxine.bonham@monash.edu.

Abstract

Introduction: Shift workers are at an increased risk of developing obesity and type 2 diabetes. Eating and sleeping out of synchronisation with endogenous circadian rhythms causes weight gain, hyperglycaemia and insulin resistance. Interventions that promote weight loss and reduce the metabolic consequences of eating at night are needed for night shift workers. The aim of this study is to examine the effects of three weight loss strategies on weight loss and insulin resistance (HOMA-IR) in night shift workers.

Methods and analysis: A multisite 18-month, three-arm randomised controlled trial comparing three weight loss strategies; continuous energy restriction; and two intermittent fasting strategies whereby participants will fast for 2 days per week (5:2); either during the day (5:2D) or during the night shift (5:2N). Participants will be randomised to a weight loss strategy for 24 weeks (weight loss phase) and followed up 12 months later (maintenance phase). The primary outcomes are weight loss and a change in HOMA-IR. Secondary outcomes include changes in glucose, insulin, blood lipids, body composition, waist circumference, physical activity and quality of life. Assessments will be conducted at baseline, 24 weeks (primary endpoint) and 18 months (12-month follow-up). The intervention will be delivered by research dietitians via a combination of face-to-face and telehealth consultations. Mixed-effect models will be used to identify changes in dependent outcomes (weight and HOMA-IR) with predictor variables of outcomes of group, time and group-time interaction, following an intention-to-treat approach.

Ethics and dissemination: The study protocol was approved by Monash Health Human Research Ethics Committee (RES 19-0000-462A) and registered with Monash University Human Research Ethics Committee. Ethical approval has also been obtained from the University of South Australia (HREC ID: 202379) and Ambulance Victoria Research Committee (R19-037). Results from this trial will be disseminated via conference presentations, peer-reviewed journals and student theses.

Trial registration number: Australian New Zealand Clinical Trials Registry (ACTRN-12619001035112).

Keywords: NUTRITION & DIETETICS; PUBLIC HEALTH; SLEEP MEDICINE.

Publication types

Clinical Trial Protocol
Research Support, Non-U.S. Gov't

MeSH terms

Diabetes Mellitus, Type 2* / prevention & control
Fasting
Humans
Insulin Resistance*
Obesity / therapy
Quality of Life
Randomized Controlled Trials as Topic
Victoria
Weight Loss