Dietary jetlag increases heart disease risk in men, study finds

Understanding Dietary Jetlag and the NutriNet-Santé Study Findings

The study analyzed the eating habits of participants to determine how schedule shifts between workdays and days off impact long-term health. Work schedules often force individuals to restrict their meal timings during the week, while weekends allow for a return to hours that align more closely with internal biological rhythms. Researchers calculated the intensity of this dietary jetlag by tracking the timing of the first and last meals of the day during both periods. When comparing weekday and weekend routines, investigators categorized the shifts into three distinct groups: an “advance” category where eating windows shifted an average of two hours earlier on weekends, a “maintien” or maintenance category where windows remained practically identical, and a “retard” category where meals were delayed by an average of one hour and forty minutes on weekends. For men, the analysis revealed that each additional hour of dietary jetlag—regardless of whether meal times were moved earlier or later—corresponded to a 14 percent average increase in the risk of developing cardiovascular diseases and a 21 percent average increase in coronary heart disease risk. Both the advance and retard groups experienced these elevated risks compared to the maintenance group.

Biological Mechanisms and Study Limitations

The human body operates on a central biological clock driven by sunlight, while peripheral organs such as the liver, pancreas, and adipose tissues synchronize themselves based on food intake. Abruptly altering meal schedules on weekends sends contradictory signals to the body, disrupting glycemic control, blood pressure, and fat metabolism, which eventually strains the cardiovascular system. Crucially, the elevated risks calculated by the research team accounted for and eliminated the impacts of other variables, including age, marital status, number of children at home, socio-professional category, smoking, alcohol consumption, physical activity levels, diet quality, and sleep duration. However, the researchers observed no statistically significant associations between dietary jetlag and cardiovascular disease risks among women. According to the study authors, this discrepancy might stem from biological and hormonal differences between the sexes or variations in lifestyle and occupational rhythms. Because this research is observational, the scientific team noted that further studies are necessary to establish direct causality.