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

Abstract

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).

“Mars Bar and a Tin of Red Bull Kept Me and My Patients Alive”: Exploring Barriers to Healthy Eating through Facebook Comments of Shiftworkers

“…Understanding and optimizing the timing of eating for shiftworkers is an established research need [ 22 ]. Strategies for scheduled eating, such as TRE and IF are popular amongst the general population and have been shown to be effective for weight loss and cardiometabolic health [ 31 , 51 , 52 , 53 , 54 ]; investigating the effectiveness and feasibility of these strategies in shiftworking populations is an emerging research area [ 22 , 55 ]. Findings of the current study suggest that altered eating schedules and not knowing when to eat is a common problem experienced by shiftworkers and thus, scheduled eating strategies may be useful in this population.…”

“…Intermittent fasting was only minimally represented in the comments of the current study, with several describing fasting as doable due to minimal time to eat on shift given their work schedule. Compared to TRE, IF has been less explored in shiftworkers, with one study currently underway [ 55 ]. While there were positive attitudes towards IF in the current study, there is emerging evidence that promoting fasting strategies could encourage disordered eating [ 57 , 58 , 59 ].…”

Fasting: From Physiology to Pathology

“…[316] The efficacy of fasting in reducing weight is also reflected in other populations, such as shift workers or obese individuals with sedentary lifestyles. [197,317,318] In contrast, fasting fails to cause weight loss in obese subjects with low income. [319,320] Interestingly, both short-term (81-day) and long-term (12-month) TRF in low-income women with obesity could result in a decrease in waist circumference, albeit no obvious effect on weight loss was observed, suggesting TRF as an alternative strategy for combating obesity socially vulnerable population.…”

Evaluation of the “Shifting Weight using Intermittent Fasting in night-shift workers” weight loss interventions: a mixed-methods protocol

“…These factors offer a target for dietary weight loss approaches for night-shift workers. In order for weight loss interventions to be successful in the night-shift working population, meal timing may need to be considered in addition to energy restriction ( 10 , 11 ). The Shifting Weight using Intermittent Fasting in night shift workers (SWIFt) study is a randomized-controlled (RCT), three-arm parallel intervention to compare the effectiveness of three dietary interventions on weight loss in night-shift workers, to investigate whether the timing of energy restriction is beneficial for night-shift workers ( 11 ).…”

“…In order for weight loss interventions to be successful in the night-shift working population, meal timing may need to be considered in addition to energy restriction ( 10 , 11 ). The Shifting Weight using Intermittent Fasting in night shift workers (SWIFt) study is a randomized-controlled (RCT), three-arm parallel intervention to compare the effectiveness of three dietary interventions on weight loss in night-shift workers, to investigate whether the timing of energy restriction is beneficial for night-shift workers ( 11 ). The SWIFt trial aims to investigate whether a 5:2 intermittent fasting approach that aligns two fast periods with night shift has benefits on both weight and metabolic outcomes ( 11 ).…”