We tend to focus on what we eat, but a huge new study suggests the time of day might matter just as much when it comes to breakfast and dinner.
Researchers looked at data from over 31,000 adults in the US and found a clear link between when people ate their first and last meals and how long they went on to live. Their findings were published in the European Journal of Clinical Nutrition. It doesn’t prove that shifting your meal times will change your lifespan, but it does add to a growing pile of evidence that timing plays a bigger role in health than we might think.
The study was extensive and extremely in-depth.
Scientists tracked more than 31,000 adults aged 40 and over, all of whom reported everything they’d eaten or drunk over a 24-hour period, including the exact time. Anything eaten after 4 a.m. counted as the first meal of the day, whether or not it was a proper sit down breakfast, and the last thing eaten became the final meal. The gap between the two was treated as each person’s eating window.
Researchers then tracked these participants for close to nine years on average, cross-checking against death records to see who had died and why. Over 7,000 participants died during that time, with heart related causes accounting for around 2,000 of those deaths. The team adjusted for things like age, smoking, exercise levels, weight, income and existing health conditions, so the patterns that showed up weren’t simply down to one group being generally less healthy than another.
Eating breakfast later was linked to a higher risk of death.
The later someone had their first meal of the day, the higher their risk of death from any cause appeared to be. Compared to eating between 7 and 8 a.m., having breakfast between 8 and 10 a.m. was linked to a 10% higher risk. That climbed to 19% for a first meal between 10 a.m. and noon, and jumped to 29% for anyone eating for the first time after midday.
The pattern was even starker for heart related deaths. People who didn’t eat until after noon had a 46% higher risk of dying from a cardiovascular cause compared to early breakfast eaters. At 50 years old, that group also had a life expectancy that was, on average, roughly two and a half years shorter.
Dinner timing told a slightly different story.
Unlike breakfast, eating dinner later didn’t simply mean a higher risk the later it got. Instead, researchers found something closer to a U shape. Eating before 7 p.m. was linked to a 13% higher risk of death compared to eating between 7 and 8 p.m., while eating after midnight came with a 27% higher risk. The lowest risk overall showed up around 8 p.m.
The lead researcher was careful to point out that this doesn’t mean 8 p.m. is the perfect dinner time for everyone. Eating very late may genuinely throw off the body’s internal clock and how it processes food, but eating unusually early could be a sign of something else going on, like illness, a restrictive schedule, or simply eating less overall. People who ate very early tended to be older and often had more existing health conditions, so their meal timing may be reflecting their health rather than causing it.
How long your eating window is didn’t seem to matter as much as when it started.
Once the researchers accounted for what time people started eating, the total length of their eating window on its own showed no clear link to how long they lived. What mattered more was the starting point rather than how many hours passed between the first and last meal. That’s a useful nuance for anyone following an intermittent fasting style approach, since simply cutting the number of eating hours in a day may not tell the whole story if the window itself falls at the wrong time.
Meal timing appears to act as a cue for the body’s internal clocks, and eating too late in the day may throw those rhythms off, potentially affecting things like blood sugar and fat processing. Animal studies have pointed to a few possible explanations, including weight gain, fat building up in the liver, and disruption to clocks in organs beyond the brain, though it’s still not clear whether the same mechanisms are behind what’s happening in people.
Why this isn’t a reason to overhaul your entire routine.
It’s important to remember that this was an observational study, meaning it can show a link without proving that meal timing directly causes any of these outcomes. Late eating could just as easily be a symptom of poor health, disrupted sleep, shift work or difficult circumstances, rather than a cause of it. A previous study on older adults found breakfast tended to shift later as people’s health declined, which fits with that idea.
Meal timing was also only recorded once, based on a single 24-hour recall, so it may not reflect someone’s habits over months or years. Other factors like natural sleep patterns and general daily routine weren’t fully accounted for either. Because of that, the researchers were clear that nobody should be making drastic changes to their eating schedule based on this alone. It’s better viewed as a signal to pay attention to, rather than a strict rule to follow.
