Calorie Restriction & Longevity

Scientists began studying whether eating less food increased the longevity of living organisms in the 1930s. Since then, they have learned that calorie restriction dramatically lengthens the lifespan of "everything from yeast to primates" and improves their health, according to a Sept. 20, 2007, Harvard Medical School news release.
There is no definitive proof that calorie restriction improves the longevity of human beings, but the research is extremely promising.

Lifespan vs. Life Expectancy

The average life expectancy of Americans has soared from about 20 years before 1800 to about 77, Stanford (Calif.) Center for Longevity director Laura Cartensen said at a longevity conference, reported the "Stanford University News" on April 22, 2009. Cartensen attributed this increase mostly to the fact that "fewer youngsters died by the age of 5" and added that the maximum lifespan of humans hasn't changed.

History of Research

According to "The New Pritikin Program," the first research on calorie restriction and longevity was performed by Cornell University scientist Dr. Clive McCay, who dramatically reduced the amount of food he fed laboratory rats in the 1930s. The result was that the rats' maximum lifespan "nearly doubled."
Since then, calorie restriction has increased the lifespan of "almost every organism it has been tried on," including fish, spiders, worms and yeast, Harvard Medical School longevity researcher David Sinclair told the "Harvard University Gazette" in an article published on May 30, 2002.

Aging Slowed

Animals on diets that have cut their calorie intake in half have lived nearly twice as long as animals on regular diets because they are "remarkably free of the common ailments of old age, including heart disease and cancer," Sinclair told the "Harvard University Gazette."
Human beings live for so long that it might take decades before scientific researchers conclude that calorie restriction improves longevity. However, experiments have already shown that humans who dramatically reduce their calories have a significantly lower rate of age-related diseases and conditions, reported the Feb. 28, 2003, edition of "Science Magazine."

Human Diseases Reduced

At a Longevity Conference at Stanford University in April 2009, Stanford assistant professor of genetics Anne Brunet reported that people who have participated in calorie-restriction experiments have had fewer cases of age-related diseases like type 2 diabetes, cancer and stroke than people who ate typical diets.
In addition, the National Institutes of Health (NIH) reported that preliminary calorie-restriction experiments showed that the risk of coronary heart disease, an age-related disease, "was significantly lower among patients who reported a history of routine periodic extended fasting." The NIH said that humans who ate significantly less than the norm had lower blood pressure and cholesterol levels.

Genes Discovered

Scientific researchers took a big step toward proving that calorie restriction in humans improves longevity when they discovered two genes that prove a diet-longevity connection.
According to a Sept. 20, 2007, Harvard Medical School press release, scientists from the NIH and Cornell and Harvard medical schools discovered two genes in "mammalian cells" that increase the longevity of those cells. "When cells experience certain kinds of stress, such as calorie restriction, these genes rev up and help protect cells form diseases of aging," reported the Harvard researchers. The genes are called SIRT3 and SIRT4.