Meal replacement as a weight loss strategy for night shift workers with obesity: a protocol for a randomized controlled trial

BACKGROUND: Shift work is considered a risk factor for a number of chronic health conditions including obesity. Weight reduction in obese patients lowers the risk for cardiovascular disease, diabetes, certain cancers, and mortality. Achieving a negative energy balance by providing low-calorie meal replacements is widely used for weight management. This study aims to evaluate the impact of a low-calorie “meal-replacement” on the weight and metabolic parameters of shift workers with obesity. METHODS: This trial will be conducted in a parallel, randomized controlled design for a period of 8 weeks. A total of 44 shift workers with body mass index over 25 kg/m(2) will be recruited after assessing eligibility. Participants will be randomly assigned to the test and control groups on a 1:1 ratio. The intervention group (N = 22) will be provided with a low-calorie (~200 kcal) meal replacement shake as dinner, and the control group (N = 22) will continue their habitual diets. The visits and the evaluations will be done as follows: screening (visit 0), 4 weeks (visit 1), and 8 weeks (visit 2). Anthropometric measurements will be taken at 0, 4, and 8 weeks. Body composition, biochemical parameters, dietary intake, and physical activity will be assessed during the first and the last visit. OUTCOMES: The primary outcome will be the proportion of participants that had a 5% body weight loss from baseline. The secondary outcomes will be post-intervention changes in other metabolic parameters. DISCUSSION: To our knowledge, this is one of the first randomized controlled trials evaluating the effects of a meal replacement as the night meal for weight loss in shift workers with obesity. Moreover, improvement of metabolic parameters in shift workers will be an added benefit to this high-risk group. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622000231741. Registered on 09 February 2022. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06784-x.