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

• Published in: BMJ open Vol. 12; no. 4; p. e060520
• Main Authors: Rogers, Michelle, Coates, Alison, Huggins, Catherine E, Dorrian, Jillian, Clark, Angela B, Davis, Corinne, Leung, Gloria KW, Davis, Rochelle, Phoi, Yan Yin, Kellow, Nicole J, Iacovou, Marina, Yates, Crystal L, Banks, Siobhan, Sletten, Tracey L, Bonham, Maxine P
• Format: Journal Article
• Language: English
• Published: England British Medical Journal Publishing Group 26-04-2022; BMJ Publishing Group LTD; BMJ Publishing Group
• Series: Protocol
• Subjects: Circadian rhythm; Clinical trials; Diabetes; Diabetes Mellitus, Type 2 - prevention & control; Energy; Fasting; Humans; Hyperglycemia; Insulin Resistance; Intervention; Metabolism; NUTRITION & DIETETICS; Nutrition and Metabolism; Obesity; Obesity - therapy; PUBLIC HEALTH; Quality of Life; Questionnaires; Randomized Controlled Trials as Topic; Shift work; SLEEP MEDICINE; Victoria; Weight control; Weight Loss; Victoria; PUBLIC HEALTH; SLEEP MEDICINE; NUTRITION & DIETETICS
• ISSN: 2044-6055; 2044-6055
• DOI: 10.1136/bmjopen-2021-060520

IntroductionShift 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 analysisA 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 disseminationThe 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 numberAustralian New Zealand Clinical Trials Registry (ACTRN-12619001035112).