Calorie restriction is the process of lowering the average amount of calories a person would normally consume in a day without depriving themselves of the essential vitamins and minerals they need to stay healthy.

An average person needs between 1,600 to 3,000 calories a day, depending on their biological sex, height, age, and activity level.

A calorie-restricted diet reduces food intake by between 20% to 40% while still meeting the recommended daily intake of essential nutrients.

When following a calorie-restricted diet, it is important to talk to a doctor or nutritionist first as cutting too many calories can lead to health issues.

Intermittent fasting can also be used as an alternative to calorie restriction as research shows it offers many of the same benefits.

For many years, researchers have studied how calorie restriction affects a person’s overall health.

Previous studies show eating fewer calories each day can support weight loss and improve cardiovascular health and cognitive function.

The current study is also not the first to link calorie restriction with longevity. Research published in April 2016 found that calorie restriction helps protect the body from aging through inflammation prevention and other mechanisms.

Moreover, a study published in September 2017 reported that calorie restriction may lead to positive changes in the genes associated with aging.

And research published in February 2022 found that following a calorie-restricted diet may help increase a person’s “health span.”

For this study, scientists examined how calorie restriction helped improve muscle health and conserve muscle function, as a decline in muscle mass and function is known to occur with aging.

“Previous studies have found that while people on calorie restriction were losing muscle mass, they did not lose muscle strength, which suggests that something occurred in the muscle that improves their performance, [and] we wanted to know what,” Dr. Luigi Ferrucci, scientific director of the National Institute on Aging and corresponding author of this study explained to Medical News Today.

“Also, there is evidence in animal models that [calorie restriction] enhances the production of spliced variants of different proteins,” he added.

Dr. Ferrucci and his team analyzed data from study participants in the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE) study. This study, supported by the National Institute on Aging, looked at whether moderate calorie restriction in humans offered the same health benefits seen in animal studies.

Although CALERIE study participants were asked to achieve a 25% calorie reduction over 2 years, the highest the group reached was a 12% reduction.

The scientists used thigh muscle biopsies from CALERIE participants to examine how calorie restriction affects human genes.

Using messenger RNA (mRNA) molecules isolated from the biopsies, researchers found that consuming fewer calories upregulated the genes associated with energy generation and metabolism, and downregulated inflammatory genes, resulting in less inflammation.

When explaining how calorie restriction may affect a person’s genes and lead to healthier aging, Dr. Ferrucci said there are many integrated mechanisms involved:

“The most directly understandable is [an] improvement of mitochondrial health and reduction of inflammation. However, very interesting is also the effect on the clock gene that regulates the rhythm of many metabolisms in our body. Overall, these and other mechanisms improve muscle health and function.”

After reviewing this study, Monique Richard, a registered dietitian nutritionist, owner of Nutrition-In-Sight, and national media spokesperson for the Academy of Nutrition Dietetics, not involved in this research, told MNT that the results of this study are not surprising, judging by data gathered by previous research.

“As we age, cellular processes [and] cell regeneration and turnover slow down,” she explained. “If we work to preserve and support these systems, we will be able to preserve function, support longevity, and quality of life.”

“An analogy would be thinking of our body as a vehicle,” Richard continued. “In order to get the most miles and performance out of a vehicle, it is important to provide quality energy — high-grade gas or electricity for the vehicle, high-quality vitamins, minerals and nutrients for our body — regular maintenance and check-ups for the functional pieces — brakes, tires, [and] engine like our brain, heart, and body — and tender, love, and care.”

“Decreasing excess, nonessential calories, but making sure individual needs are met, will preserve cellular function [and] muscle tissue and extend the ability for cells to function and turnover,” she noted.

MNT also spoke with Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA, about this study. Dr. Cutler was not involved in this research.

He commented he was happy this study was done as it helps get the message out to people that it is, in some cases, better to eat less.

“The public health aspects are the most important thing — just getting the message out to people about eating less and the dangers posed by being overweight, by being obese, by having diabetes, and all the other ramifications of overeating,” said Dr. Cutler.

For those looking to cut calories, Dr. Cutler said there are certain food groups to start with.

“I’d start number one with processed meats,” he detailed. “Any meat that has been salted or cured or processed in any way — the salamis, the bolognas, the hotdogs. These should all be off our list. I think red meat in general should be severely limited. And carbohydrates should be geared towards a much lower glycemic index — less sweet and processed carbohydrates.”