Avoiding late-night meals may help you live longer.

According to a mouse study, meal time is crucial for maximizing the anti-aging effects of calorie restriction.

Mice that only ate during the active part of their circadian cycle lived over 35 percent longer on a calorie-restricted diet than control mice who ate whenever they wished.

Mice on a calorie-restricted diet who only ate when they were sedentary survived just 10% longer than control mice.

If the findings hold true in humans, people should limit their calorie intake and avoid eating late at night to extend their lives.Diets that drastically restrict total calorie consumption while providing all required nutrients have been shown to increase average lifespan in worms, flies, rats, and monkeys.

Food shortages cause physiological changes in all of these organisms that improve longevity and delay the development of age-related disease, according to the findings.

Calorie-restricted eating plans

Though concrete data is currently lacking, Trusted Source in humans, which involves cutting average calorie intake by roughly a third, may also enhance human lifetime.

The circadian clock, which controls daily cycles of physiology, metabolism, and behaviors like eating, has been shown in animal experiments to have an effect on calorie restriction time. This has been connected to aging as well.

This prompted researchers at the University of Texas Southwestern Medical Center in Dallas, Texas, to look into whether meal timing affects the life-extending effects of calorie restriction.

Calorie restriction has been demonstrated in numerous studies to enhance the average longevity of mice. However, the majority of this study has involved scientists feeding laboratory mice calorie-restricted diets during the day.

Mice, unlike humans, are nocturnal, meaning they evolved to feed at night.

As a result, the researchers installed automatic feeders to ensure that some of the mice only ate at night during their research.

How the research was carried out

They divided the animals into six groups to see if meal time had an influence on lifespan, independent of calorie restriction and fasting.

The animals in one group, which functioned as a control, were free to consume whatever they chose (as much as they wanted, whenever they wanted).

The remaining 5 groups followed calorie-restricted diets (30–40% fewer calories) but had various feeding times.

Mice on an ad libitum diet lasted 800 days on average, while mice on a calorie-restricted diet with food accessible 24 hours a day lived 875 days, or 10% longer.

Mice on a calorie-restricted diet who ate only during the day (during their circadian cycle's inactive phase) and fasted for 12 hours overnight lived for 959 days. To put it another way, they lived nearly 20% longer than the controls.

The mice who were fed solely during their active period and then fasted for the remaining 12 hours lived the longest. The average longevity of these animals was 1,068 days, which was over 35% longer than the control animals.

The researchers published their findings in the journal Science.

Dr. Joseph Takahashi, senior author and Howard Hughes Medical Institute Investigator and chair of neurology at UT Southwestern Medical Center, says, "We have identified a new dimension to calorie restriction that greatly improves lifespan in our lab animals."

"If these findings hold true in individuals, we would want to reconsider whether that midnight snack is actually necessary," he says.

Aging gracefully

They also discovered that calorie-restricted meals enhanced the animals' glucose regulation and insulin sensitivity, with the biggest gains shown in mice who ate only at night (their active phase).

According to Dr. Takahashi, this indicates that the mice were healthier and aged more slowly.

Aging raised the activity of genes involved in inflammation and lowered the activity of genes involved in metabolism and circadian rhythms in all of the mice, according to the researchers.

Calorie restriction reduced these age-related changes, but mice who only ate at night benefited the most.

"Because aging involves a progressive ramping up of inflammation," Dr. Takahashi explained, "calorie restriction is delaying this age-related increase in inflammation, which is also consistent with delaying the aging process."

Sleep disturbance

The authors point up some of the study's limitations.

Sleep disruption in mice that ate during the day (during their inactive period) may have contributed to their lower longevity, they write.

Furthermore, the mice in the study were all male. Ovarian hormones may provide some protection against abnormalities in circadian rhythms in females, according to the scientists.

The study, like any research involving animal models, may not translate well to people.

If the findings are applicable to people, who have the active phase opposite that of mice, the researchers indicate that eating early in the evening is ideal for good aging.

One day, medications targeting circadian genes or the proteins they produce may be developed to imitate the anti-aging effects of eating just during the active phase of the day.

"We're working on this concept and looking for medications that can help with circadian alignment," Dr. Takahashi added. "Crossing my fingers!"

Blood sugar levels have risen.

Eating late at night interferes with the body's capacity to maintain a balanced blood sugar level.

A recent study found this was particularly true for people with a particular variation of the gene for the melatonin receptor.

Melatonin is a hormone that helps to govern the sleep-wake cycle. As its levels increase in the evening, this not only triggers sleepiness but also impairs insulin secretionTrusted Source.

As a result, the body has more difficulty controlling blood sugar levels after meals close to bedtime.

“Since many people opt for carbohydrate-rich snacks in late evenings, such as chips, cookies, candy, or popcorn, these snacks are more likely to impair blood sugar control and increase one’s risk for prediabetes and diabetes,” said Mariam Eid, R.D., L.D., a dietitian and founder of A Happy AOneC, which advises teens and young adults recently diagnosed with prediabetes.

"As a result, eating carbohydrate-rich meals and snacks earlier in the day promotes better blood sugar balance and helps to prevent prediabetes and diabetes," says the study.