Eat less to live longer? Several recent studies show that eating fewer calories (known as calorie restriction) may Benefit for health… to the point where it can even extend the lifespan. This service life extension observed in mice, among other animals. Findings suggesting that eating less can slow down the cellular aging process. demonstrated in rat cells. At the moment, we have no evidence of this beneficial effect on human aging. But the first randomized trial in healthy people would show that we, too, can benefit from this lifelong good, even if the effect seems small.
Assessment of biological aging after 24 months of calorie restriction
A study conducted at Columbia University in the USA and published February 9, 2023 in the journal Nature Agingestimated the effect of reducing calorie intake by 25% over two years. A total of 220 healthy adults aged 20 to 50 years (mean 38 years), including 70% of women (pre-menopause), were randomly divided into two groups: 105 were on a calorie-restricted diet and 59 were able to eat as much as possible. less. how much you wanted. Calorie reduction was calculated based on each person’s caloric requirements at baseline (assessed after two weeks of follow-up prior to intervention).
To analyze aging, the researchers studied the rate of DNA methylation, a mechanism that is part of epigenetics that controls gene expression. This methylation changes with aging, which makes it possible to estimate a person’s biological age. To do this, they collected blood samples from the participants at the beginning of the intervention, after 12 months, and at the end of the study (at 24 months). Three calculation methods were used to calculate biological age from DNA methylation, and thus to estimate the rate of aging between these three time points.
This interference will have little effect on the rate of aging.
Not surprisingly, the biological age of all participants increased over time. But the rate of this aging seemed to be slightly slower in the calorie restricted group: their rate of aging slowed by about 2-3 percent compared to people without dietary restrictions. However, this result is not very reliable, since it was observed with only one of the three calculation methods (no difference with the other two). There was no significant difference between men and women.
This small effect may be due to lower than expected calorie restriction. Indeed, the majority of participants in this group failed to reduce their calorie intake by 25%, with an average of only 12%. But the effect seems very real because it depended on the “dose” of treatment: those who managed to restrict calories by more than 10% had a more noticeable slowdown in cellular aging than those who had a restriction of less than 10%. On the other hand, it is obviously not possible to conclude that caloric restriction actually affects lifespan, since the study participants were not followed up for more than two years of the study.
Longer life doesn’t necessarily mean slower aging
These early results in humans are encouraging, but need to be confirmed by examining other markers of cellular aging. Because it is possible that what is observed is not a real effect on aging, but on the health status of individuals, which is not necessarily the same thing. The same study has already shown that calorie restriction, for example, improved participants’ heart health (results published in 2019), among other physiological markers of health status. It is possible that the epigenetic changes identified in the study reflect improved health rather than aging, in part because two of the three calculation methods used did not show an intervention effect.
This is reminiscent of the results obtained in November 2022 by German researchers (published in NatureCommunication), which showed in mice that multiple life-prolonging interventions in mice would have no real effect on aging. For example, intermittent fasting, a diet similar to calorie restriction, improves several aspects of health, but this improvement is independent of age. That is, according to the authors, this diet prolongs life by reducing the risk of death, and not by slowing down aging. Thus, the findings of this Columbia University study should be treated with caution pending confirmation before we can say that eating less can actually slow down the passage of time for us.