Researchers still don’t know exactly why cutting calories may slow aging, but there is evidence it prompts changes at the cellular level.
Eating fewer calories appears to slow the pace of aging and increase longevity in healthy adults, according to a study published Thursday in the journal Nature Aging.
The study, which was funded by the National Institute on Aging, part of the National Institutes of Health, is the first-ever randomized controlled trial that looked at the long-term impact of calorie restriction.
It adds to an already large body of evidence that a calorie-restricted diet can provide substantial health benefits, including delayed aging, said the study’s senior author, Dan Belsky, who is assistant professor of epidemiology at Columbia University’s Mailman School of Public Health in New York City.
“The main take-home of our study is that it is possible to slow the pace of biological aging and that it may be possible to achieve that slowing through modification of lifestyle and behavior,” Belsky said.
In a phase 2 clinical trial, which ran for two years, 220 adults were randomized to cut their caloric intake by as much as 25% — 500 calories for people who generally consume 2,000 calories a day — or to make no changes to their diet. The participants had a body mass index, or BMI, ranging from 22 to 27.
People in the calorie-restricted group were given three prepared meals each day for the first month to familiarize themselves with portion sizes. They were also provided behavioral counseling about diet over the first 24 weeks. The participants who weren’t in the calorie-restricted group weren’t told how much they should eat and did not get any counseling.
Dr. Evan Hadley, director of the geriatrics and clinical gerontology division at the National Institute of Aging, said that most people in the calorie-restriction group only ended up cutting their daily caloric intake by about 12%.
“But that 12% was enough to have significant changes,” he said.
To measure the rate of aging, the researchers used an algorithm to see how certain DNA biomarkers in the blood changed over time.
The algorithm was based on previously acquired data from about 1,000 people who were followed for 20 years to see how rapidly their organ functioning — including the heart, liver, kidney and lungs — declined as they grew older, Belsky said. The algorithm, he added, acted as a sort of “speedometer,” helping to gauge how quickly participants in the study were aging.
The researchers found that people who cut their calories slowed the pace of their aging by 2% to 3%, compared to people who were on a normal diet.
That translates, Belsky said, to a 10% to 15% reduction in the likelihood of dying early.
“We all have the power to change the trajectories of aging,” he said.
It’s not yet known whether the slowdown in aging would hold out after two years, Hadley said. Participants in the study were not followed up with after the two-year intervention. A separate study, also funded by the agency, is planning to look at the effects of a calorie-restricted diet after 10 years, he added.
Still, Hadley said, the new study reinforces findings from previous research that some calorie restriction can promote health benefits, including living longer and healthier lives.