Хооллох цаг хугацаа нь хүний эрүүл мэнд, наслалтад нөлөөлж болзошгүйг судалгаагаар тогтоожээ

Most breakfast advice focuses on what to put on your plate. But a large study of US adults suggests the clock may deserve attention, too: The time you consume your first and last calories of the day could be linked to how long you live.

The findings show an association, not proof that changing the clock changes a person’s fate. Still, they add to evidence that health may depend not only on what we eat, but when.

Earlier studies linked skipping breakfast and late-night eating with poorer health, but the risks associated with specific times remained unclear.

Researchers therefore analyzed data from 31,044 adults aged 40 and older in the US National Health and Nutrition Examination Survey between 1999 and 2018.

Participants reported everything they had eaten or drunk during the previous 24 hours, including the time of each item.

The study, published in the European Journal of Clinical Nutrition, decided that any calorie-containing food or drink consumed after 4 am could count as the “first meal,” meaning it was not necessarily a conventional sit-down breakfast.

The final caloric intake became the last meal, and the time between them became the eating window.

The team linked these records to deaths registered through the end of 2019.

During a median follow-up of 8.6 years, 7,129 participants died, including 2,259 from cardiovascular causes.

The analysis accounted for factors including age, smoking, physical activity, diet quality, body mass index, energy intake, income, and existing disease.

A pattern emerged as the first meal moved later.

Compared with eating between 7 and 8 am, a first meal between 8 and 10 am was associated with a 10 percent higher risk of death from any cause. The difference rose to 19 percent between 10 am and noon, and 29 percent after noon.

Cardiovascular mortality followed a similar trajectory.

Eating for the first time after noon was associated with a 46 percent higher risk of cardiovascular death than eating between 7 and 8 am. At age 50, the later group also had an estimated life expectancy 2.46 years shorter on average.

The day’s final meal produced a more surprising result.

Rather than risk simply rising with every later hour, the relationship was U-shaped. Compared with finishing between 7 and 8 pm, eating before 7 pm was associated with a 13 percent higher risk of death from any cause, while eating after midnight was associated with a 27 percent higher risk. The lowest modeled risk was around 8 pm.

“However, this does not mean that 7-8 pm is a universally optimal dinner time for everyone,” senior author Zhilei Shan, from Huazhong University of Science and Technology, told ScienceAlert.

Very late eating may disrupt circadian rhythms and metabolism, Shan explained. But a very early last meal could reflect schedules, illness, or lower energy intake.

Early eaters tended to be older, eat less often, and have more existing illness, so the clock may be revealing something about their health rather than causing it.

The eating window added another complication.

Once first-meal timing was considered, its length showed no consistent relationship with mortality across the whole sample. Its association instead varied according to when eating began.

That adds nuance to concerns about very short eating windows: Counting fasting hours alone may miss part of the picture.

“Meal timing is an important cue for peripheral circadian rhythms,” Shan said. “A later first meal or late-night eating may contribute to circadian misalignment and metabolic disturbances, including impaired lipid and glucose metabolism.”

Animal studies point to possible pathways involving weight gain, fat accumulation in the liver, disrupted clocks in organs outside the brain, and altered fat absorption. Whether these mechanisms explain mortality patterns in people remains unknown.

Reverse causation is also possible. Late eating may be a consequence or marker of poor health, poor sleep, shift work, or socioeconomic circumstances. A previous study of older adults similarly found thatbreakfast shifted later as health problems accumulated.

“Therefore, later eating should be interpreted as a potential risk marker, and possibly a modifiable behavior, rather than definitive evidence of a direct causal effect,” Shan said.

Related: Men And Women May Need Different Breakfasts For Weight Loss

The study’s biggest limitations follow from its observational design. Meal timing was primarily captured by a single 24-hour recall at the start, which may not represent years of habitual eating.

Chronotype, detailed sleep patterns, activity timing, and other unmeasured factors could still influence the results despite extensive adjustments and sensitivity analyses.

“Based on these findings alone, people should not make extreme changes to their eating schedules,” Shan said.

The study was published in theEuropean Journal of Clinical Nutrition.