Key takeaways
- Researchers followed 104,806 French adults for a median of 8.1 years to investigate “eating jet lag”—differences between weekday and weekend meal timing.
- Among men, each additional hour of eating jet lag was associated with a 14% higher relative risk of cardiovascular disease and a 21% higher relative risk of coronary heart disease.
- Both earlier and later weekend eating schedules were associated with coronary heart disease in men compared with keeping meal times relatively consistent.
- Researchers found no statistically significant association in women or with cerebrovascular disease.
- The study was observational, so it cannot show that changing meal times causes heart disease or that keeping a consistent eating schedule prevents it.
Many people eat according to the clock during the workweek but relax their schedules on weekends. Breakfast becomes brunch, dinner moves later, and the day’s entire eating window may shift by several hours.
Regularly shifting the timing of meals between weekdays and weekends is known as “eating jet lag”.
Could repeatedly changing that schedule matter for heart health?
A large prospective study published in Communications Medicine suggests there may be an association, particularly in men.
Researchers analyzing data from more than 100,000 adults found that larger differences between weekday and weekend eating times were associated with higher risks of cardiovascular disease and coronary heart disease among male participants (Le Folcalvez et al., 2026).
The researchers call this pattern “eating jet lag.” Like social jet lag—the mismatch between weekday and weekend sleep schedules—it describes a recurring shift in the timing of a daily behavior.
However, the study found an association, not cause and effect. Its findings do not mean that an occasional late breakfast, brunch, or weekend dinner is harmful to the heart.
What is eating jet lag?
Eating jet lag refers to the difference between the timing of a person’s eating window on workdays and days off.
Researchers calculated it using the midpoint between each participant’s first and last caloric intake of the day.
For example, someone who consumes calories from 7 a.m. to 7 p.m. has an eating midpoint of 1 p.m. If that person eats from 10 a.m. to 10 p.m. on weekends, the midpoint shifts to 4 p.m.—a difference of three hours.
This measurement captures a shift in the overall eating window. It is not simply a measure of eating breakfast or dinner late.
Researchers also classified participants according to the direction of the weekend shift:
- Maintenance: The weekend eating midpoint remained within one hour of the weekday midpoint.
- Advance: The midpoint shifted more than one hour earlier on weekends.
- Delay: The midpoint shifted more than one hour later on weekends.
About 71% of participants maintained a relatively consistent schedule, 5% shifted earlier, and 24.2% shifted later.
How the study was conducted
The study included 104,806 adults participating in the French NutriNet-Santé cohort between 2009 and 2023. The average age at enrollment was 42.7 years, and 79% of participants were women.
Participants completed repeated 24-hour dietary records documenting what they consumed and when. Each participant provided an average of 5.8 records that included both weekdays and weekends.
Researchers followed participants for a median of 8.1 years. Across 814,338 person-years of follow-up, they documented 2,368 cardiovascular events:
- 1,270 coronary heart disease events
- 1,098 cerebrovascular events
Reported cardiovascular conditions were validated using medical records and administrative health databases.
The researchers adjusted their statistical models for numerous factors that could influence cardiovascular risk, including age, education, employment, marital status, physical activity, smoking, alcohol consumption, body mass index, energy intake, diet quality, family cardiovascular history, and average daily meal timing.
A secondary analysis among participants with available sleep data also considered bedtime, sleep duration, and social jet lag.
What did the researchers find?
The clearest associations appeared among men.
For each additional hour of eating jet lag, male participants had:
- A 14% higher relative risk of cardiovascular disease
- A 21% higher relative risk of coronary heart disease
In the smaller subgroup with available sleep information, the estimates remained similar: approximately 15% higher relative risk for cardiovascular disease and 20% higher relative risk for coronary heart disease.
These figures describe relative differences in risk. They do not mean that a man’s personal chance of developing heart disease increases by 14 or 21 percentage points every time his eating schedule shifts by an hour.
Nor can these results predict how changing an individual’s meal schedule would affect his personal risk. Actual cardiovascular risk depends on many factors, including age, smoking, blood pressure, cholesterol, diabetes, family history, and existing cardiovascular disease.
Both earlier and later weekend schedules were associated with risk
The direction of the weekend shift also produced an interesting result.
Compared with men who maintained relatively consistent weekday and weekend eating schedules, men whose eating midpoint shifted more than one hour earlier on weekends had:
- A 44% higher relative risk of cardiovascular disease
- A 68% higher relative risk of coronary heart disease
Men whose eating midpoint shifted later had a 36% higher relative risk of coronary heart disease.
The estimated 14% increase in overall cardiovascular disease risk among men who shifted their eating later was not statistically significant.
This means the findings cannot simply be interpreted as evidence that “eating late on weekends is bad.” Both substantial advances and delays in the eating schedule were associated with coronary heart disease in men, with the larger estimates appearing among those who shifted earlier.
Researchers also observed that the relationship appeared to level off at around 1.5 hours of eating jet lag. However, relatively few participants had very large differences in their eating schedules, making estimates at the upper end less certain.
What about women and stroke?
Researchers did not find statistically significant associations between eating jet lag and cardiovascular disease among women.
They also found no statistically significant association between eating jet lag and cerebrovascular disease.
That does not prove that meal-time irregularity has no cardiovascular relevance for women or no relationship with stroke. Rather, this particular study did not provide sufficient statistical evidence of those associations.
The sex difference is especially notable because women represented 79% of the study population.
Why might changing meal times matter?
Human physiology follows approximately 24-hour circadian rhythms that help coordinate sleep, metabolism, hormone activity, and cardiovascular function. Light is the primary timing signal for the brain’s central circadian clock, while food intake can act as a timing signal for peripheral clocks in organs involved in metabolism.
Researchers have proposed that repeatedly shifting food intake relative to the body’s internal rhythms could contribute to circadian misalignment.
Experimental studies involving altered sleep and eating schedules have found changes in metabolic and cardiovascular markers, providing some biological support for this possibility.
However, the NutriNet-Santé study did not directly test how eating jet lag might affect the cardiovascular system. It therefore cannot establish that circadian disruption explains the associations researchers observed.
Eating jet lag could also be a marker for other lifestyle patterns. People whose eating schedules vary substantially may differ in work schedules, stress, sleep, nighttime light exposure, exercise, medication timing, or other behaviors that could independently influence cardiovascular health.
Why was the association found only in men?
The study cannot explain why statistically significant associations were observed in men but not women.
Biological differences, lifestyle patterns, work schedules, or other factors could potentially contribute, but the research was not designed to determine the reason for the sex difference.
Importantly, a lack of statistical significance in women does not establish that irregular meal timing is harmless for women. It means this study did not provide sufficient evidence of an association among female participants.
Earlier research involving the same French cohort also produced a different pattern. A 2023 study linked later first and last meals with cardiovascular outcomes, with some associations particularly apparent among women (Palomar-Cros et al., 2023).
The two studies examined different questions.
The earlier investigation focused on whether people generally ate earlier or later in the day. The newer study examined how much an individual’s eating schedule changed between weekdays and weekends.
Someone could eat relatively late every day while maintaining a highly consistent schedule. Another person could eat early during the workweek and several hours later every weekend.
Those are different exposures and should not be treated as interchangeable.
The male-specific finding in the newer study is therefore better viewed as a result requiring further investigation rather than evidence of a settled biological difference between men and women.
How do the findings compare with earlier research?
The new findings add to growing research examining not only what people eat but also when—and how consistently—they eat.
Later meal timing and cardiovascular risk
A 2023 NutriNet-Santé study involving 103,389 adults examined the timing of participants’ first and last meals.
Having a first meal later in the day was associated with greater cardiovascular risk, while later last meals were also associated with cardiovascular outcomes (Palomar-Cros et al., 2023).
That study also suggested that a longer overnight fasting period may be more favorable when achieved by finishing the day’s eating earlier rather than delaying the first meal.
Like the newer research, however, it was observational and cannot establish that changing meal times would change cardiovascular risk.
Irregular eating patterns and cardiometabolic health
A smaller U.S. study followed 115 women for one year. Greater variability in daily eating patterns and larger weekday-to-weekend timing differences were associated with less favorable cardiometabolic measures, including blood pressure and blood-sugar control (Makarem et al., 2021).
Again, the findings were associations and do not establish causation.
Experimental evidence from simulated night work
Experimental research offers limited mechanistic support.
In a randomized controlled trial, 20 healthy adults were assigned to simulated night work with either daytime-and-nighttime eating or daytime-only eating; 19 participants were included in the reported analyses.
The daytime-and-nighttime group experienced unfavorable changes in measures of cardiac autonomic function and plasminogen activator inhibitor-1 (PAI-1), a protein involved in blood-clot regulation, while these changes were not observed in the daytime-only eating group (Chellappa et al., 2025).
Because researchers deliberately manipulated meal timing, the experiment provides stronger evidence about short-term physiological effects than an observational study can.
But it was small and short-term, and it measured cardiovascular risk markers—not heart attacks, strokes, or long-term cardiovascular disease.
Taken together, these studies suggest that the cardiovascular relevance of diet may extend beyond food quality and calorie intake to include when people eat and how consistent that timing is.
They do not yet establish an ideal eating schedule for preventing cardiovascular disease.
Important limitations
Several limitations affect how the findings should be interpreted:
- The study cannot establish causation. It was observational, so researchers cannot determine whether eating jet lag itself contributed to cardiovascular disease.
- Workdays were assumed. Researchers treated Monday through Friday as workdays and weekends as days off, which may not reflect the schedules of shift workers and others with nontraditional workweeks.
- Meal timing was self-reported. Repeated dietary records provide substantial detail but remain vulnerable to reporting and recall errors.
- The participants were not nationally representative. NutriNet-Santé participants tend to be more educated and health-conscious than the general French population.
- Women were overrepresented. Women made up 79% of the cohort even though the statistically significant eating-jet-lag associations were observed primarily in men.
- Residual confounding is possible. Researchers adjusted for many cardiovascular risk factors, but unmeasured or imperfectly measured behaviors could still influence the results.
- Sleep data were available for only a subset of participants. This limits researchers’ ability to fully separate eating jet lag from differences in sleep and social jet lag.
- The findings may not generalize to other populations. Meal culture, work schedules, lifestyles, and baseline cardiovascular risk differ across countries and populations.
- Multiple comparisons were conducted. The researchers reported that they did not apply a specific statistical correction for multiple comparisons, making independent replication particularly important.
The NutriNet-Santé cohort also experienced fewer cardiovascular events than the broader French population, further limiting how directly the risk estimates can be applied to other groups.
Should you keep the same meal times every day?
The evidence does not justify prescribing an exact breakfast, lunch, or dinner time for everyone.
It also does not suggest that occasionally sleeping late, having brunch, eating a late dinner, traveling, or disrupting your normal schedule will damage your heart.
The study examined habitual differences in eating schedules over time—not isolated meals.
Maintaining reasonably consistent meal times may be a practical habit for people whose eating and sleep schedules otherwise vary substantially. But there is not yet enough evidence to prescribe meal-time consistency as a proven strategy for preventing cardiovascular disease.
It should also remain secondary to heart-health measures backed by much stronger evidence, including:
- Not smoking
- Exercising regularly
- Eating a nutritious diet
- Managing blood pressure and cholesterol
- Managing diabetes when present
- Getting adequate sleep
- Taking prescribed medications as directed
People should not replace established medical care or proven cardiovascular prevention strategies with an unproven meal-timing regimen.
Frequently asked questions
Does eating later on weekends cause heart disease?
No. The study found an association between differences in weekday and weekend eating schedules and cardiovascular outcomes in men. Because it was observational, it cannot establish that changing meal times caused heart disease.
Is eating earlier on weekends healthier than eating later?
Not according to this study. Both earlier and later weekend shifts were associated with coronary heart disease among men compared with maintaining a relatively consistent schedule. The larger risk estimates were actually observed among men whose eating midpoint shifted earlier.
Does a one-hour change increase everyone’s heart disease risk by 14%?
No. The 14% figure is a relative-risk estimate from the male participants in this study. It is not an individual prediction, and it does not mean a person’s absolute risk rises by 14 percentage points.
Did eating jet lag increase stroke risk?
The researchers did not find a statistically significant association between eating jet lag and cerebrovascular disease.
Should everyone eat breakfast before 8 a.m.?
No. This study did not assign participants to specific breakfast times and cannot establish a universal ideal time for breakfast.
Previous observational research has found associations between later first meals and cardiovascular outcomes, but that does not prove that eating breakfast before a particular hour prevents heart disease.
Is eating jet lag the same as intermittent fasting?
No. Eating jet lag describes how much the timing of a person’s eating window changes between workdays and days off.
Intermittent fasting and time-restricted eating generally focus on how long someone eats or fasts each day. A person could follow time-restricted eating while keeping the same schedule every day and therefore have little eating jet lag.
Final thoughts
The study adds meal-time consistency to a growing area of research on circadian rhythms and cardiovascular health.
Among men, larger differences between weekday and weekend eating schedules were associated with higher risks of cardiovascular and coronary heart disease. However, the observational findings do not show that irregular meal timing caused those outcomes or that keeping identical meal times would prevent them.
For now, maintaining reasonably consistent meal times may be a practical habit for people who want to do so, but it should not be treated as a proven method of preventing heart disease.
Established measures—including avoiding tobacco, exercising regularly, eating a nutritious diet, getting adequate sleep, and appropriately managing blood pressure, cholesterol, and diabetes—remain far better supported by evidence.
References
Chellappa, S. L., Gao, L., Qian, J., Vujovic, N., Li, P., Hu, K., et al. (2025). Daytime eating during simulated night work mitigates changes in cardiovascular risk factors: Secondary analyses of a randomized controlled trial. Nature Communications, 16, 3186. https://doi.org/10.1038/s41467-025-57846-y
Le Folcalvez, X., Obeid, E., Palomar-Cros, A., Fezeu, L. K., Bourhis, L., Bellicha, A., et al. (2026). Eating jetlag based on meal timing discrepancies and risk of cardiovascular disease using the prospective cohort NutriNet-Santé. Communications Medicine, 6, 453. https://doi.org/10.1038/s43856-026-01758-5
Makarem, N., Sears, D. D., St-Onge, M.-P., Zuraikat, F. M., Gallo, L. C., Talavera, G. A., Castaneda, S. F., Lai, Y., & Aggarwal, B. (2021). Variability in daily eating patterns and eating jetlag are associated with worsened cardiometabolic risk profiles in the American Heart Association Go Red for Women Strategically Focused Research Network. Journal of the American Heart Association, 10(18), e022024. https://doi.org/10.1161/JAHA.121.022024
Palomar-Cros, A., Andreeva, V. A., Fezeu, L. K., Julia, C., Bellicha, A., Kesse-Guyot, E., Hercberg, S., Romaguera, D., Kogevinas, M., Touvier, M., & Srour, B. (2023). Dietary circadian rhythms and cardiovascular disease risk in the prospective NutriNet-Santé cohort. Nature Communications, 14, 7899. https://doi.org/10.1038/s41467-023-43444-3
