What we eat and when we eat it are important lifestyle factors that shape our wellbeing, and scientists continue to unearth valuable insights into exactly what habits can bring the most benefits to our health. New research has probed this question through a multi-year study in hundreds of mice, and found that a careful balance of restricting calorie intake and limiting eating to the most active hours of the day could significantly extend lifespan.
Scientists are piecing together a sizable body of evidence around the ways fasting might impact long-term health in positive ways. One compelling 2017 study from Harvard, for example, showed how fasting can slow aging and improve health by bringing youthful plasticity to mitochondrial activity inside our cells.
Other studies since have probed the biological mechanisms underpinning this relationship, with some fascinating results. One in 2019 demonstrated that fasting can drive metabolic changes in the blood associated with longevity and healthy aging. Mouse studies have also shown that fasting can boost gene expression associated with improved long-term memory and reduced age-related cognitive impairment. Meanwhile, studies on monkeys have shown that caloric restriction can also increase lifespan and improve health.
The latest findings in this area come from a team at the Howard Hughes Medical Institute, who studied hundreds of mice that were placed on different dieting regimes over a four-year period. The scientists set out to explore not just how time-restricted eating can slow aging, but how, when paired with careful caloric restriction, its effects might be enhanced even further.
The mice were housed with automatic feeders, with some allowed to eat as much as they wanted, while others had calories restricted by 30 to 40 percent and underwent different eating schedules, with some being fed only at night when they were most active. The calorie restriction alone was found to extend the rodents' lifespan by 10 percent, but when combined with the night-time only eating, their lifespan was extended by 35 percent.
The results indicate that time-restricted eating benefits the body and does so independently of weight loss. An interesting study published last month found limiting food intake to short periods of time each day to be no more effective for weight loss than restricting calories. Indeed, the authors of this new study observed no difference in body weight between the mice on different eating schedules, but "profound differences in lifespan,” according to study author Joseph Takahashi.
The combination of reduced caloric intake with night-time eating added nine months to the typical two-year lifespan of the mice. A similar plan in humans would equate to eating only in the daytime hours, according to the scientists. Learning more about the way calorie-restrictive diets interact with the body clock, known as our circadian rhythm, is a key focus for the scientists moving forward. This could lead to more effective calorie-restricted diets or even drugs that mimic these effects.
"iIf we find a drug that can boost your clock, we can then test that in the laboratory and see if that extends lifespan," said Takahashi.
The research was published in the journal Science.
Source: Howard Hughes Medical Institute
