The randomized controlled trial found evidence contradicting the belief that dietary interventions can’t modify how fast a person ages.
Though previous research has found that limiting calories slows the aging process in mice, worms, and flies, the effects of calorie restriction on humans have remained unclear.
Now, new research published online in the journal Nature Aging found evidence that reduced caloric intake may have the same anti-aging effect on humans.
The 'Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy' (CALERIE™) Phase-2 randomized controlled trial — funded by the U.S. National Institute on Aging and led by the Butler Columbia Aging Center at the Columbia University Mailman School of Public Health — is the first of its kind to examine the effects of long-term calorie restriction in humans.
The study included 220 healthy men and women without obesity. At recruitment, the research team analyzed the participant’s blood samples for biomarkers that measure how quickly a person is aging.
Specifically, they looked at the PhenoAge and GrimAge clocks, which are measurements of DNA methylation data — also known as 'epigenetic clocks.' These clocks estimate biological age and can gauge how much aging has occurred in the body. In addition, the team also measured DunedinPACE, an indicator of how fast biological aging occurs.
Then, the participants were randomized to either a regular diet or a diet with a calorie intake 25% below the participant’s baseline.
The team followed up by taking more blood samples after 12 months and again at 24 months.
After analyzing the data, the scientists found that calorie restriction slowed the speed at which the participants aged, especially for the DunedinPace measure. However, according to the GrimAge clock, calorie restriction only modestly postponed increases in age.
In contrast, the PhenoAge measurements did not show any of these effects and may have indicated an opposite effect.
The study authors suggest that their findings contradict the belief that aging rates may not be modifiable and add evidence that calorie restriction may have the same positive impact on aging in humans as previous studies have shown in animals.
In a news release, co-lead author Calen Ryan, Ph.D., a research scientist at Columbia’s Butler Aging Center, said:
"Our findings are important because they provide evidence from a randomized trial that slowing human aging may be possible. They also give us a sense of the kinds of effects we might look for in trials of interventions that could appeal to more people, like intermittent fasting or time-restricted eating."
According to the news release, the research team is continuing to follow-up the study participants to determine if calorie restriction has any long-term benefits on healthy aging.
What is calorie restriction?
Although not appropriate for everyone, calorie restriction is a dietary approach where a person reduces their caloric intake below what is considered typical or average for their age, sex, weight, and activity level.
However, calorie restriction is not the same as skipping meals or engaging in extreme diets that eliminate entire food groups. Instead, it is a gradual and controlled reduction in caloric intake, typically accompanied by a balanced diet including a variety of foods to ensure that the body receives all the essential nutrients it needs.
But before embarking on a limited-calorie diet, it’s important to discuss it with a healthcare professional, as a low calorie diet may not be safe for everyone.