Restrict Those Calories For Long-term Health

July 10, 2009|By Karen Kaplan | Karen Kaplan,Tribune Newspapers

For a country in which about 200 million people are overweight or obese, scientists have discouraging news: Even those who maintain a healthy weight probably should be eating less.

Evidence has been mounting that the practice of caloric restriction - essentially, going on a permanent diet - greatly reduces the risk of age-related diseases and even postpones death. It has been shown to extend the lives of yeast, worms, flies, spiders, fish, mice and rats.

Now, in a study funded by the National Institutes of Health and released today, many of the same benefits have been demonstrated in primates, the best evidence yet that caloric restriction would help people.

The findings, published in the journal Science, tracked rhesus monkeys that were on a reduced-calorie regimen for as long as 20 years. The animals' risk of dying from cancer, heart disease and diabetes fell by more than two-thirds.

The study comes as some validation to the cadre of Americans who profess to practice caloric restriction in their daily lives. It was also welcomed by scientists who study the biological mechanisms of aging and longevity.

"It adds to the evidence piling up that caloric restriction, independent of thinness, is a healthy way to stay alive and healthy longer," said Susan Roberts of the Human Nutrition Research Center on Aging at Tufts University, who wasn't involved in the study. Fewer "diseases in old age has to be something most everyone wants."

Although the regimen sounds grueling, it is hardly a starvation diet, experts said.

It typically begins with an assessment to determine how many calories an individual needs to consume to maintain a healthy weight. Then that number is shaved by 10 percent to 30 percent.

People on caloric restriction can eat three meals a day. A typical menu includes cereal with fruit and nuts for breakfast, a big salad for lunch and dinner featuring lean meat and reasonable portion sizes. There's also room for a couple of snacks and even a small dessert from time to time.

Caloric restriction has produced consistent health benefits for animals.

In the new study, scientists tracked 76 adult rhesus monkeys from the Wisconsin National Primate Research Center starting in 1989. Half the animals were fed a typical diet of lab chow, and the rest got a version with a higher concentration of vitamins and minerals to make up for the 30 percent reduction in chow quantity.

Over the course of the study, the monkeys that ate the regular diet were three times more likely to die of an age-related disease than their counterparts on caloric restriction. Fourteen deaths in the control group were attributable to age-related diseases, compared with five such deaths among the animals that ate 30 percent fewer calories, according to the study.

In all, the monkeys on caloric restriction "appear to be biologically younger than the normally fed animals," the researchers wrote in their report.

Scientists aren't sure why eating less slows the aging process, but theories abound.

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