Navigating Nutrition in a 24/7 World: A Scoping Review of Dietary Intake and Chrononutrition Assessment in Shift...

Shift work affects 15-20% of the global workforce and significantly increases risk for obesity, type 2 diabetes, and cardiovascular disease. While dietary disruption is a recognised mechanism, whether research adequately captures meal timing as a critical metabolic determinant remains limited. This scoping review systematically mapped dietary and chrononutrition assessment in shift workers following PRISMA-ScR guidelines, searching five databases through July 2025. Quality assessment was conducted using the Joanna Briggs Institute checklists. Twenty-four studies representing 27,537 participants from 13 countries were included. Shift workers demonstrated consistent dietary disruption with heterogeneous energy patterns: 55% reported excess intake (103-303 kcal/day), 14% showed substantial deficits (1521-1698 kcal/day), and 14% found no differences despite temporal redistribution. Despite energy variability, macronutrient patterns were consistent: increased saturated fat and simple carbohydrates (63%), reduced fibre (24% decrease), and lower fruits, vegetables, and micronutrients (vitamin D, calcium, iodine, iron, carotene). Diet quality indices deteriorated in 88% of studies. Critically, 54% of studies examining shift worker diet failed to assess chrononutrition variables. Among the 46% measuring meal timing, results were remarkably consistent: eating windows extended 2.3-2.6 h, caloric midpoint delayed ~2 h, and last meals occurred 2-3 h later during night shifts, with later timing and longer eating windows consistently associated with greater daily energy intake (β = 0.32(N)-0.47(D); p < 0.001). This evidence mapping reveals that shift work is associated with disruption of both dietary composition and meal timing, yet chrononutrition remains critically neglected. Future research should prioritise validated, time-stamped dietary assessments and test timing-based interventions addressing this modifiable risk factor.