- A study in mice suggests that meal timing is important for maximizing the anti-aging effects of calorie restriction.
- On a low-calorie diet, mice that ate only during the active phase of their circadian cycle lived almost 35% longer than control mice that ate when they wanted to.
- Mice on a low-calorie diet that ate only during their inactive phase lived only 10% longer than control mice.
- If the results hold true for humans, they suggest that to maximize lifespan, people should reduce calorie intake and avoid late-night eating.
Research shows that in all of these organisms, food shortages trigger physiological changes that promote longevity and delay the onset of age-related diseases.
Animal studies have revealed that the timing of caloric restriction can have an effect due to the circadian system, which controls the daily cycles of physiology, metabolism, and behaviors such as eating. This has also been linked to aging.
This led researchers at the University of Texas (UT) Southwestern Medical Center in Dallas, Texas to investigate whether meal timing contributes to the effects of calorie restriction on lifespan.
Numerous studies have shown that calorie restriction increases the average lifespan of mice. But most of that research has involved scientists feeding lab mice during the day on low-calorie diets.
Unlike humans, mice are nocturnal, meaning they evolved to feed at night.
So for their study, the scientists used automatic feeders to ensure that some mice ate only at night.
To determine if meal timing had an effect on lifespan – independent of calorie restriction and fasting – they divided the animals into 6 groups.
In one group, which served as a control, the animals could eat ad libitum (as much as they wanted, when they wanted).
The remaining 5 groups followed low-calorie diets (30-40% fewer calories) with the same total calorie intake but different eating schedules.
Control mice eating ad libitum had a median lifespan of 800 days, while mice on a low-calorie diet with food available 24 hours a day lived 875 days, or 10% longer.
Mice on a low-calorie diet that only ate during the day (the inactive phase of their circadian cycle) and fasted for 12 hours overnight lived 959 days. In other words, they lived almost 20% longer than the controls.
But the calorie-restricted mice that ate only during their active phase and then fasted for the remaining 12 hours lived the longest. These animals recorded an average lifespan of 1,068 days, nearly 35% longer than the control animals.
The scientists reported their findings in Science.
“We have discovered a new facet of calorie restriction that dramatically extends the lifespan of our laboratory animals,” says lead author Dr. Joseph Takahashi, a Howard Hughes Medical Institute researcher and chair of neuroscience at UT Southwestern Medical Center.
“If these findings turn out to be true in people, we might want to rethink if we really want that midnight snack,” he adds.
They also found that low-calorie diets improved the regulation of glucose levels and insulin sensitivity in animals, but the improvements were greatest for mice that ate only at night (their active phase).
This suggests the mice were healthier and aged more slowly, Dr. Takahashi said. Medical News Today.
The researchers found that, in all mice, aging increased the activity of genes involved in inflammation and decreased the activity of genes involved in metabolism and circadian rhythms.
Calorie restriction slowed these age-related changes, but mice that ate only one night saw the greatest benefits.
“Since aging can be thought of as a gradual rise in inflammation, [calorie restriction] also delays this age-related increase in inflammation, which is also consistent with delaying the aging process,” Dr. Takahashi said.
The authors note some limitations of their study.
In particular, they write that sleep disruption in mice that ate during the day (during their inactive phase) may have contributed to their shorter lifespans.
Additionally, all of the mice in the study were male. The authors write that in women, ovarian hormones may provide some protection against disruptions in circadian rhythms.
As with all research involving animal models, the study may not translate well to humans.
If the results apply to humans, who have the opposite active phase than mice, the scientists suggest that eating early at night is better for healthy aging.
One day, it may even be possible to develop drugs that target circadian genes, or the proteins they make, to mimic the anti-aging benefits of eating only during the active phase.
“[W]We are working on this idea and researching drugs that can improve circadian alignment,” Dr. Takahashi said. “Crossed fingers!”
Eating late at night interferes with the body’s ability to keep blood sugar within a healthy range.
A recent study found that this was especially true for people with a particular melatonin receptor gene variation.
Melatonin is a hormone that helps regulate the sleep-wake cycle. As its levels increase in the evening, it not only triggers drowsiness, but also
As a result, the body has a harder time controlling blood sugar levels after meals close to bedtime.
“Since many people opt for late-night carbohydrate-rich snacks, such as chips, cookies, candy, or popcorn, these snacks are more likely to impair blood sugar control and increase the risk of prediabetes and diabetes,” said Mariam Eid, RD. , LD, registered dietitian and founder of A Happy AOneC, which counsels adolescents and young adults recently diagnosed with prediabetes.
“Therefore, eating carbohydrate-rich meals and snacks earlier in the day promotes better blood sugar control and helps prevent prediabetes and diabetes,” she said. DTM.