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Restrict Calories, Revive Your Life

Forget about super-sizing, a restricted-calorie diet may add health, youthfulness, and longevity to your life.

WebMD Feature

Reviewed By Brunilda Nazario

Looking to tack a few years on to the end of your life, or enjoy your golden years with vigor, good health, and youthfulness? Research on animals shows a restricted-calorie diet may have these effects and slow the hands of time.

Now, practitioners of calorie restriction are hoping that human beings can also drink from the fountain of youth. While only time will tell if it actually works, experts and believers weigh in on the science behind the theory, and the pros and cons of a restricted-calorie diet.

The Science

With evidence dating back to 1935, when Cornell scientist Clive McCay unexpectedly discovered that rats on a calorie-restricted diet lived nearly 30% longer than those on "normal" diets, according to a Cornell press release, scientists have been testing the impact of a calorie-restricted diet on everything from mice and worms, to flies, spiders, guppies, dogs, and primates.

"There seem to be two mechanisms by which a restricted-calorie diet increases life span," says Mark Mattson, PhD, chief of the Laboratory of Neurosciences at the National Institute on Aging. "First, it reduces free radical production, or the production of highly damaging forms of oxygen, and the second is that calorie restriction increases the resistance of cells to stress. We think that both of these are important in protecting against a number of different diseases that have a negative impact on life span, such as cardiovascular diseases and cancer."

A restricted-calorie diet has been shown to reduce cholesterol levels and improve blood glucose levels in animals, but the burning question, now, is will a restricted-calorie diet have any long-term benefits for humans?

"There is a lot of evidence to support the benefits of a restricted-calorie diet in rats and mice and other species," says Mattson. "And we can assume that because calorie restriction is important in mice and rats, it's probably important in humans as well, because rats and mice have the same physiology as humans -- they get diabetes and cancers and many of their causes of death are the same as humans."

So it might work, but what's the cost?

Cutting Calories

The underlying premise of calorie restriction, according to the Calorie Restriction Society web site, is, "to eat fewer calories, while not consuming fewer vitamins, minerals, and other components of a healthy diet, and by doing so achieve a longer and healthier life."

The bottom line? The average male in the U.S. consumes about 2,745 calories every day, and the average female 1,833 calories, according to the CDC. A calorie-restricted diet, depending on how severe a person wants to practice, takes that number and, over time, reduces it by more than one-third.

In 2000, Dean Pomerleau, at 35 years old, 5 feet 8 inches and 172 pounds, described himself as pretty typical.

"My weight was creeping up and I was beginning to see the signs of my own mortality," says Pomerleau, who lives in Pittsburgh. "I was on the downhill side of my youth, and then I heard about the calorie- restriction diet, and the science behind it intrigued me -- that it had a real serious potential for health and longevity. I ended up giving it a try and it really agreed with me."

Four years later and 51 pounds lighter, Pomerleau practices a rigid form of calorie restriction that balances lower calorie intake with proper nutrition.

"I eat the same thing twice a day, seven days a week, 365 days a year," says Pomerleau, of his diet of 1,200 calories a day. "It's a lot of veggies with olive oil-based salad dressing, a lot of mixed fruits, almonds and hazelnuts, and flaxseed oil for omega-3 fatty acids."

Along with a rigorous exercise plan, Pomerleau believes this is adding longevity and quality to his life.

"The animal data, if we can extrapolate, which is pretty extensive all the way up to dogs and primates, suggest that for every calorie you forgo, you can add about 30 seconds on to your life span," says Pomerleau. So in essence, "If you have a slice of pizza, you give up three hours of life. If you skip that slice, you'll get that three hours back. Would you rather have the pizza, or live for three more hours? But it's not just about longevity, there are a number of health and psychological benefits that are here now that are at least rewarding for me than as is the potential for life span expansion."