Evaluating the Accuracy of Declared Eating Schedules by Continuous Glucose Monitoring

Background/Objectives: Chrononutrition is an emergent field concerning the effect of eating patterns on human health and their relationship with biological rhythms. Current evidence points towards the benefits of early eating in the prevention of non-communicable diseases and circadian health. Despite the importance of eating/fasting rhythm, current methods are neither specific nor validated against physiological variables. This work aimed to explore an objective metabolic outcome, postprandial glucose, as an accuracy indicator of self-declared meal schedules registered in a mobile app. Methods: A 1-week protocol of ambulatory monitoring of meal schedules, glucose, and circadian variables was performed in 20 young adults. Meal annotations were registered using KronoEat 1.0, a smartphone app, allowing for both prospective and recall entries. A circadian monitoring device provided data on movement intensity, distal skin temperature, and prospective food annotation. Results: Participants annotated an average of 3.5 food events/day/participant with KronoEat. Breakfast (92.7%) and lunch (86.4%) showed the highest proportion of food events related to a glycemic excursion, whereas this proportion was lower for dinner (79.7%) and snacks (67.7%). Postprandial glucose after main meals differed significantly from average glucose levels. Interesting couplings were found in circadian variables and glucose-for example, between post-breakfast glycemic excursions and the morning increase in activity. Conclusions: Meal schedules registered under free-living conditions in KronoEat show high levels of correlation with postprandial glucose and glycemic excursions derived from continuous glucose monitoring.