It works in the lab—what about the real world?

By Jillian Kramer
Updated May 24, 2017
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Calorie Restrictions
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It seems that eating dramatically fewer calories than usual has a bevy of benefits: it can help you shed pounds, catch better Z's, and even improve your sex life. And a new study suggests reducing your caloric intake could even increase your lifespan. (At least, it does in mice.)

Does that mean you should start eating mini foods at every meal? Maybe not quite yet, say experts.

The study in question, published in Molecular & Cellular Proteomics, analyzed two sets of mice, one that was allowed unlimited access to food and another that was given 35 percent fewer calories than their normal diets. (Don't worry: despite their dip in calories, the mice were still getting all the nutrients they needed to survive.) At the end of the experiment, researchers at Brigham Young University saw that the calorie restricted diet had slowed down the rodents' cells rate of aging.

As the study itself notes, this isn't the first time a connection has been made between eating fewer calories and living longer. (In fact, this 2014 study offers up a similar conclusion.) However, there's no direct evidence that the same mechanism works in humans, and there's no real evidence our species can add years to our lives by reducing our diets.

A better plan, then, is to attempt to not exceed the calories your own body needs each day. Rather that significantly restricting our calorie intake, says Keri Gans, R.D. and author of The Small Change Diet., we should identify our ideal number of daily calories and aim to eat that number through a mix of healthy fruits, vegetables, lean proteins, and whole grains. "Most people are overeating, and not eating the proper amount [or ingredients] for ideal health," she says.

Your magic calorie count, of course, has a lot to do with your gender, age, and lifestyle, and the USDA has a chart to help you determine just how many calories you might need each day. But no matter your metrics, Gans warns that number should never dip below 1,200 calories. "That's dangerously low for the average person," she says. "Most people need between 1,500 to 2,000 calories per day."

If you find you're eating too many calories on any given day, be careful what you cut out. Like those mice, you still need to get enough nutrients to support your body function, says Claire Shorenstein, M.S., R.D., and C.D.N. "In other words, you cannot simply cut calories from wherever you like," she says. "You still need to maintain some nutritional balance in what you eat to prevent malnutrition from occurring." It should go without saying, but lean proteins, fruits, and vegetables can't be cut so that you can eat a slice of pizza and still hit your daily calorie count.

What's more, severely cutting calories over the long term often doesn't work. While it's possible to maintain a healthy lifestyle—eating the correct number of calories—over the years, it's anything but easy to restrict calories for long stretches of time. "Calorie restriction is not sustainable," warns Brigitte Zeitlin, M.P.H., R.D., C.D.N. "As humans, we often overeat later to make up for our restrictive diet patterns." Severely cutting calories can lead to unhealthy yo-yo dieting. "You want to eat better, not less," she says.

Should a human study on longevity and calorie-cutting be conducted, we may find that reducing our diets is the key to a longer life. But until then, these experts recommend that you try to eat exactly what you need—no more, and no less.

In the meantime, you can eat your way to anti-aging benefits by adding antioxidant-rich foods—think: vegetables, fruits, nuts, seeds, legumes, and whole grains—to your diet, Zeitlin says. "Antioxidants fight free radicals in your body that cause mature signs of aging, disease, and inflammation," she explains. "So, to actually feel andlook younger, eat more plant based foods."