Irregular meal timing linked to higher cardiovascular disease risk, French study finds
A groundbreaking study has found that maintaining consistent meal times throughout the week is crucial for cardiovascular health. The research, published Tuesday, September 1, in the journal Communications Medicine from Nature Portfolio, demonstrates that alternating between different eating schedules on workdays versus days off significantly elevates the risk of cardiovascular and coronary heart diseases.
The study was conducted by researchers from the French National Research Institute for Agriculture, Food and Environment (INRAE), the French National Institute of Health and Medical Research (INSERM), and Sorbonne Paris Nord University and Paris Cité University. The team introduced the term "eating jet lag" to describe the mismatch in meal timing between weekdays and weekends, a pattern they found particularly harmful to men's heart health.
This phenomenon extends far beyond shift workers. While approximately 14% of the UK working population—over 4 million people—work shifts that naturally disrupt eating patterns, the demands of modern life mean that social and eating jet lag affect the general population broadly. Many people delay morning meals, adopt irregular eating patterns, and extend eating into nighttime hours due to work, family, and social commitments.
The biological mechanism behind eating jet lag
The human circadian system operates through a central clock located in the suprachiasmatic nucleus of the brain and peripheral clocks embedded in metabolic tissues. While light exposure primarily synchronizes the central clock, feeding schedules serve as critical synchronizers for peripheral clocks throughout the body. This dual-clock system explains why mistimed eating can disrupt metabolic function even when sleep patterns remain stable.
"During the week, we do not necessarily live according to our natural biological rhythm, but rather to the one imposed by society or our work. In a sense, we are forcing our internal clocks, while on weekends, many people return more to their natural rhythm, which causes a shift."
Bernard Srour, a research director at INRAE who supervised the study, explained the shift. Srour, who coordinates the French National Cancer Food Research Network and has previously demonstrated links between ultra-processed foods and cancer, cardiovascular disease, type 2 diabetes and obesity, brings extensive expertise in nutritional epidemiology to this emerging field of chrononutrition—a growing scientific discipline investigating the relationship between circadian rhythms, nutrition, and metabolism.
Broader health implications of circadian disruption
The cardiovascular risks identified in the French study align with broader patterns observed in shift work research. A 2018 meta-analysis found that shift workers face approximately 17% higher risk of cardiovascular disease events and 26% higher coronary heart disease morbidity compared to day workers. The health consequences of circadian disruption extend even further: the World Health Organization has classified shift work as a probable carcinogen due to its impact on biological rhythms.
Controlled laboratory studies have demonstrated how rapidly mistimed eating can damage metabolic health. When researchers redistributed participants' eating to nighttime hours, subjects developed elevated cholesterol, increased blood pressure, and heightened inflammation. In simulated night-shift protocols, approximately one-third of participants became prediabetic in just ten days, illustrating the swift metabolic consequences of eating at odds with circadian rhythms.
The findings underscore that meal patterns can vary dramatically based on professional obligations, family commitments, and social activities, all of which can disrupt the body's internal timing systems. The research suggests that maintaining regular meal schedules throughout the entire week, rather than alternating between weekday and weekend patterns, may represent an important but often overlooked strategy for protecting cardiovascular health in modern society.
