We already know that eating too much is detrimental to your health. But what if eating less is better for you in more than one way? According to a new study, restricting calorie intake can help slow down the aging process down to your genetic material.

The recommended calorie intake can vary substantially based on things like your height, sex, and lifestyle, but a commonly-cited rule of thumb approximates the recommended calorie intake for women to 2,000 and 2,500 for men. In the study, scientists at Columbia University, New York, carried out a randomized control trial with 220 healthy adults, asking half of them to cut their calories by a quarter.

They followed the participants’ diet and overall health for two years, taking blood samples at the start of the study, midway through it, and at the end. Looking at key DNA markers, they found a clear difference between those who had cut down on their calorie consumption and those who had not.

Eating less is like giving up smoking

Getting people to eat less isn’t easy. People in the calorie-restricted group had to be counseled and familiarized with how their new portions will look. They were given three prepared meals each day for the first month, so they could get used to it. But even like this, most couldn’t stick to a 25% calorie reduction.

Instead, researchers estimate that most people in the calorie-restriction group only ended up cutting their daily caloric intake by about 12%. But 12% was enough to see the differences.

It’s always challenging to interpret this type of genetic change, but researchers note that the speed of DNA aging was 2-3% slower for the people on the calorie-restricted diet. They say this translates to a 10-15% decrease in the risk of early death. That’s about the same type of impact you’d see in someone who quit smoking.

In day-to-day life, this could carry implications for people who implement dietary strategies such as intermittent fasting or time-restricted eating.

“Our findings are important because they provide evidence from a randomised trial that slowing human ageing may be possible,” said Calen Ryan, a Research Scientist at Columbia’s Butler Aging Center and co-lead author of the study. However, Ryan also added the calorie restriction may not be the way to go for everyone.

Other researchers also praised the work, but said it doesn’t add much new information — instead, it just seems to confirm what we already knew (or strongly suspected).

“This seems [to be] well-done research on complex markers in the context of a small-scale calorie reduction trial, but do we really need to prove that eating less calories slows aging processes?” asks Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow. “This should be evident from national data sets that show people from Japan who remain leaner than most are amongst the longest-living of any nation.  There is also evidence from trials that drugs that remove excess sugar calories and appear to help attenuate “cellular overnutrition” also lower many outcomes linked to ageing such as heart failure or chronic kidney disease.   This new work, therefore, fits with an emerging body of evidence all pointing in the same direction.”

Indeed, previous studies on both animals and humans have also suggested that calorie-restricted diets can have a beneficial effect on health, but this is still insufficiently explored (and is difficult to explore because of the complexity of the involved phenomena).

Meanwhile, Duane Mellor, a registered dietitian and senior lecturer at Aston University in the UK emphasized that we shouldn’t be making any major decisions based on this study, and having a healthy, varied nutrition, is more important.

“Although interesting, it is important to be cautious and not encourage especially older adults just to reduce their food intake to slow ageing.  As, in ageing adults, maintaining a healthy weight, being physically active and eating a varied and healthy diet with enough protein is known to reduce the risk of falls.”

A follow-up of trial participants is now ongoing to determine if the intervention had long-term effects on healthy aging.

The study was published in Nature Aging.