‘Eating Jetlag’ Was Linked to Higher Heart Risk in Men

Moving breakfast and dinner several hours between workdays and weekends may do more than change appetite. A large French cohort study found that greater “eating jetlag” was associated with higher cardiovascular risk in men, even after researchers accounted for diet quality and several lifestyle factors.

Eating jetlag heart risk was examined in 104,806 adults followed through the NutriNet-Santé project. For men, each additional hour of difference in the midpoint of daily eating between weekdays and weekends was associated with a 14% higher risk of cardiovascular disease and a 21% higher risk of coronary heart disease in the primary analysis. The study did not show that irregular meal timing caused those outcomes.

Published September 1 in Communications Medicine, the research adds timing consistency to a growing discussion about nutrition. What people eat remains central, but the body’s circadian system may also respond to when the eating window shifts from one part of the week to another.

What Eating Jetlag Heart Risk Means

Eating jetlag does not refer to traveling across time zones. It describes a recurring shift in meal timing between structured days and less structured days. Researchers calculated the midpoint between a person’s first and last caloric intake, then measured how far that midpoint moved between weekdays and weekends.

For example, someone who regularly eats from 7 a.m. to 7 p.m. has a 1 p.m. eating midpoint. If the weekend window moves to 10 a.m. through 10 p.m., the midpoint moves to 4 p.m.—three hours of eating jetlag.

The study treated both earlier and later weekend shifts as potentially meaningful. Among men, moving the eating midpoint earlier by more than an hour was associated with higher cardiovascular and coronary risk than maintaining timing within one hour. Moving it later was associated with higher coronary risk, although the total cardiovascular association for that group was not statistically significant after full adjustment.

Why Meal Timing Could Matter

The body uses light as a major signal for its central clock, but food intake can influence clocks in organs involved in metabolism, including the liver and pancreas. Large, recurring shifts in eating time may create a mismatch between behavioral schedules and these internal rhythms.

That mechanism is biologically plausible, but this study did not directly measure circadian disruption inside participants’ organs. It observed meal-timing patterns and later health events, then adjusted statistically for factors including age, occupation, education, smoking, alcohol, physical activity, BMI, energy intake and dietary patterns.

How Strong Was the Association?

During 814,338 person-years of follow-up, researchers recorded 1,270 coronary events and 1,098 cerebrovascular events. In the overall sample, each additional hour of eating jetlag was associated with an 8% higher cardiovascular risk before sleep adjustment. The association weakened and was no longer statistically significant in the smaller subgroup with detailed sleep data.

The clearer finding appeared in men. The association remained after adjustment for bedtime and sleep duration: cardiovascular risk was 15% higher per additional hour, and coronary risk was 20% higher. Researchers found no evidence of an association with stroke-type events.

The dose-response curves appeared to level off at about 1.5 hours, which argues against interpreting every additional minute as a continuously escalating danger. The findings describe relative risk in a population, not an individual’s immediate chance of a heart attack.

Why the Finding Was Different in Women

No statistically significant association was detected in women, even though women made up 79% of the cohort. The authors discuss possible biological and occupational explanations, but the study cannot establish why the patterns differed.

There is another important caution: the formal statistical interaction between sex and eating-jetlag intensity was not significant. That means the research did not prove that meal-timing effects truly differ between men and women. The male-only association is a subgroup result that should be tested in other cohorts.

What the Study Does Not Prove

Participants chose to join a long-running nutrition study and may be more health-conscious than the general population. Food timing was self-recorded, and the researchers assumed that weekdays were workdays and weekends were non-workdays. That assumption will not fit every participant, especially shift workers and people with nontraditional schedules.

Although cardiovascular events were checked against medical records, residual confounding remains possible. Irregular meal timing could reflect work stress, caregiving, sleep disruption or other factors that were not perfectly measured. The study also made several comparisons without a specific correction for multiple testing.

Most importantly, this was not a randomized trial. It cannot tell us whether asking people to keep meal timing within one hour will reduce cardiovascular events.

A Practical Way to Use the Finding

For someone with a conventional schedule, the most reasonable interpretation is modest: avoid swinging the entire eating window by several hours every weekend when consistency is realistic. That could mean keeping the first and last meals in roughly the same part of the day, rather than forcing an inflexible clock-based routine.

Consistency across sleep, exercise and eating may also be easier to sustain when treated as a pattern instead of three separate rules. In our recent coverage of regular exercise and sleep restfulness, people who started and maintained activity reported better sleep outcomes. The shared lesson is not perfection; it is building rhythms the body and schedule can repeat.

Why This Story Matters Now

Nutrition advice often emphasizes food quality and calorie totals while treating time as a minor detail. This study suggests timing regularity may deserve more attention, particularly for people whose workdays and free days create large behavioral shifts.

It may be especially relevant to shift workers, although the study’s weekday-versus-weekend definition was not designed to map complex rotating schedules. Future trials will need to test whether stabilizing meal timing produces measurable benefits and whether the same approach works across sexes, cultures and work patterns.