Cutting calories by 25% can slow the rate of aging in humans and lead to a significant reduction in mortality risk, according to a new study from Columbia University.

In a randomized controlled trial, one group was fed a calorie-restricted diet for two years, while others followed their regular diets. Researchers examined levels of a biomarker in the volunteers’ DNA — measured before and after the study — that’s known to change with age.

Results showed those eating a calorie-restricted diet displayed a 2% to 3% slowing in the pace of aging, which, according to earlier studies, equates to a 10% to 15% reduction in mortality risk — similar to that experienced by a smoker who has quit.

Calen Ryan, research scientist at Columbia’s Butler Aging Center and co-lead author of the study, acknowledged long-term calorie restriction isn’t practical for much of the population.

“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.”

The team is now monitoring the trial’s participants to see whether slowing the pace of aging in the short term could have longer-term effects on healthy aging.