Cutting Calories Could Slow the Pace of Aging: Study

3 min read

Feb. 14, 2023 – A new study says we can slow the pace at which we age by 2% to 3% if we lower the number of calories we eat by 25%. That may seem like a little benefit for a large cut in calories. But experts say it's actually a pretty big deal. 

“In other studies, that same difference in pace of aging had meaningful consequences for people's risk of dying,” says senior study author Daniel W. Belsky, PhD, a researcher at the Butler Columbia Aging Center at Columbia University Mailman School of Public Health in New York City.

Cutting calories by 25% slowed down the pace of aging in young and middle-aged adults by a few percentage points, compared to people who continued eating normally, the new research reveals. This first-of-its-kind study in humans adds to evidence from animal studies that the rate of aging can be changed. 

Compared to 75 people who ate normally, the 145 people randomly assigned to cut back their calories slowed their pace of aging by 2% to 3% over 2 years in the  randomized controlled trial. 

For example, a similar slowdown in the pace of aging was associated with a 10% to 15% lower risk of dying over 10 to 15 years in previous work, Belsky says. “So 2 to 3% slower aging doesn't sound like maybe that big of a deal – but 10 to 15 percent reduction in risk of dying seems like a big deal.” 

Results of the study were published last week in the journal Nature Aging

Even though the pace of aging slowed, the researchers did not find significant changes on two biological aging measures in the study, suggesting more work is needed. 

The findings “are intriguing in that caloric restriction seemed to show a slower pace of aging in healthy adults,” says Vandana Sheth, a registered dietitian nutritionist and owner of a nutrition consulting firm in Los Angeles. “This can have a significant impact on population health. However, larger studies need to be done to follow up on these findings.”

‘Exciting Result’

Asked if the findings imply aging could be slowed down in people, Belsky said, “That is the … exciting result from the trial. These results suggest it may be possible to slow the pace of biological aging with a behavioral intervention.”

But not everyone is completely convinced. 

“This is good suggestive evidence that caloric restriction can modify aspects of biological aging in humans, similar to what has been known in laboratory animals for many decades,” says Matt Kaeberlein, PhD, director of the Healthy Aging and Longevity Research Institute at the University of Washington in Seattle and senior author of Antiaging diets: Separating fact from fiction,” a 2021 review article in Science. 

Part of his concern is that cutting your calories by a quarter may not be a sustainable long-term strategy.  

“It’s important to keep in mind that these measurements only report on a portion of biological aging and are probably not an accurate overall measurement of biological age or the rate of biological aging,” Kaeberlein says. The findings might suggest that “at the population level, a 25% reduction in caloric intake is unlikely to have large effects on biological aging unless implemented over many years, which is likely not reasonable for most people.”

Insight Into Intermittent Fasting?

Cutting back on calories is related to other dietary strategies, including intermittent fasting and time-restricted eating, Belsky says. “Intermittent fasting and time-restricted eating are nutritional interventions that have been developed, in part, because in experiments with animals, they have some of the same biological effects as calorie restriction.”

There remain many unanswered questions. 

“There are people who would argue that the reason calorie restriction does what it does is because when people are calorie-restricted, they also tend to restrict the times when they eat,” Belsky says. “They tend to have these longer fasts during the day.”