Eating Jetlag: Weekend Meal Times and Heart Health

A large French cohort study published on 1 September 2026 in Communications Medicine found that men whose first and last meals moved between weekdays and weekends had a higher rate of cardiovascular disease over the following years. The researchers call that weekly shift "eating jetlag". The study is observational, the association was reported in men, and the authors themselves say it needs to be confirmed elsewhere.

What eating jetlag means

You probably know the idea of social jetlag: sleeping on one schedule during the work week and another on days off. Eating jetlag is the same idea applied to food. The paper defines it as meal timing regularity between free days and work days.

If breakfast is early on a Tuesday and mid-morning on a Sunday, your eating day has shifted, even if the food on the plate is identical. The plain language summary of the paper notes that fixed work schedules often force people to adapt their eating rhythm through the week, and that this kind of shift can disrupt biological clocks and circadian rhythms. That is the reason the team went looking for a link with heart disease.

What the study did

The data come from NutriNet-Santé, a French prospective cohort that followed volunteers between 2009 and 2023.

Who	104,806 adults, 79% women, mean age 42.7 years
Design	Prospective observational cohort
Diet data	Repeated 24-hour dietary records, 5.8 per person on average
Exposure	Absolute difference between weekends and weekdays in the times of the first and last caloric intake
Outcome	Cardiovascular disease, self-reported and validated against medical records
Follow-up	Median 8.1 years

The researchers measured eating jetlag in two ways. Intensity is the size of the gap between weekend and weekday timing, whichever direction it goes. Direction sorts people into three groups: "Advance" (eating earlier on weekends than on weekdays), "Maintenance" (about the same) and "Delay" (eating later on weekends).

They then used statistical models adjusted for many other factors to compare how often cardiovascular disease appeared in each group.

What it found

The associations were reported in male participants.

• Intensity. In men, eating jetlag was associated with a higher risk of cardiovascular disease (hazard ratio 1.14, 95% confidence interval 1.05 to 1.23) and of coronary heart disease (hazard ratio 1.21, interval 1.11 to 1.33).
• Eating earlier on weekends. Men in the "Advance" group had higher risks of cardiovascular disease (hazard ratio 1.44, interval 1.08 to 1.93) and coronary heart disease (hazard ratio 1.68, interval 1.19 to 2.39) than men in the "Maintenance" group.
• Eating later on weekends. Men in the "Delay" group had a higher coronary heart disease risk (hazard ratio 1.36, interval 1.05 to 1.77) than men in the "Maintenance" group.

A hazard ratio above 1 means the event was more common in that group over the follow-up period. The abstract does not say what increment of eating jetlag the intensity figures refer to, so they should not be read as "per hour".

What about women? The abstract gives no figures for women. It reports the associations "in male participants", and its conclusion says the results suggest a role for meal timing regularity in cardiovascular disease "specifically in males". The plain language summary puts it as "especially among males". Since 79% of the cohort were women, that is a notable gap, not a footnote.

The authors add that the association was independent of sleep duration and diet quality, meaning it remained after their models accounted for both.

What it does not show

This is the part to read slowly.

• It is observational. Nobody was assigned to regular or irregular meal times. People who keep steady meal times may differ from people who do not in ways the models cannot fully capture, such as the kind of job they have. An association is not proof that the shift itself causes heart disease.
• Meal times came from self-reported diet records. An average of 5.8 recorded days per person is a sample of someone's habits, not a complete picture.
• Weekends stood in for days off. The full paper names this as its main limitation: work schedules were not collected, so Monday to Friday was assumed to be working days and Saturday and Sunday rest days. That will be wrong for some participants.
• The result is confined to men in a cohort of French volunteers who were mostly women.
• It awaits confirmation. The authors write that "if confirmed in other studies, meal timing regularity could be a strategy to mitigate cardiovascular disease risk". That sentence starts with "if".

So the study does not show that moving your weekend breakfast lowers your heart risk. No one has tested that here.

What this means if you fast

Intermittent fasting is, among other things, a decision about when your first and last meals happen. If you already keep an eating window on workdays, this study is a reason to notice what happens to it on Saturday, not a reason to worry about one late brunch.

A few low-stakes observations:

• A schedule you can keep seven days a week is easier to keep regular than one that only fits your office days. If your current plan falls apart every weekend, a gentler window may suit you better. Our guide on choosing a fasting schedule for your lifestyle walks through that choice, and the fasting schedule overview lists the common options.
• How you arrange food inside the window still matters for how you feel. See how to structure your eating window for sustained energy.

Fasting content is general information, not medical advice. If you are pregnant or breastfeeding, have diabetes or take blood-sugar medication, have a history of eating disorders, take other regular medication, or are under 18, talk to a doctor before fasting. If you have heart disease or are being treated for cardiovascular risk factors, changes to how you eat belong in a conversation with the person treating you.

QoFast is a fasting tracker app for iPhone and Android, with intermittent plans (16:8, 18:6, 20:4, OMAD and custom) and a fasting history that lets you see when your fasts actually started and ended on each day of the week. It gives general information, not medical advice. It is free to download, with an optional Pro subscription: App Store and Google Play.

FAQ

What is eating jetlag? It is the difference in meal timing between work days and free days. In this study it was calculated from the times of the first and last caloric intake on weekends compared with weekdays.

Does eating at the same time every day protect your heart? This study cannot answer that. It found an association in men in an observational cohort, and the authors say the finding needs confirmation in other studies before meal timing regularity could be considered a strategy.

Did the study find the same thing in women? The abstract reports the associations in male participants and describes the result as specific to males. It gives no figures for women.

Sources

• Le Folcalvez X, et al. "Eating jetlag based on meal timing discrepancies and risk of cardiovascular disease using the prospective cohort NutriNet-Santé." Communications Medicine, 1 September 2026. DOI: 10.1038/s43856-026-01758-5, PubMed 42680779