( consume the most calories have a shorte...)Caloric restriction won't dramatically extend life span in humans: UCLA research

consume the most calories have a shorter life span, and that if people severely restrict their calories over their lifetimes, their life span increases by between 3 percent and 7 percent -- far less than the 20-plus years some have hoped could be achieved by drastic caloric restriction. He considers the 3 percent figure more likely than the 7 percent.

"The trade-off between calories and longevity appears to be close to a linear relationship, but the slope isn't very steep," said Phelan, whose model predicts the relationship between calories consumed and life span.

Phelan's conclusion is that the few extra years of life are not worth the suffering necessary to achieve them.

"Do you want to spend decades severely limiting what you eat to live a few more years? You will be unhappy and then your life will end shortly after mine ends," Phelan jokes.

Scientists have known for six decades that cutting the caloric intake of rodents by 40 percent or 50 percent results in dramatically longer lives for them.

"You can practically double their life span," Phelan said. "The same result has been found in fish, spiders and many other species. If it works for them, some thought, it should work for us; I'm here to tell you it doesn't."

Phelan, co-author of the book, "Mean Genes," conducted his dissertation at Harvard University 10 years ago on caloric restriction and on why it works in extending the lives of rodents.

"When you restrict the caloric intake of rodents, the first thing they do is shut off their reproductive system," said Phelan, citing a finding from his dissertation. A normal rodent reaches maturity at one month of age, and begins reproducing its body weight in offspring every month and a half. If humans shut off reproduction by severely limiting calories, "our reduction in wear and tear on the body is minimal," he said.

The rodents placed on severely restricted diets bit people who tried to hold them, and
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Source:University of California - Los Angeles

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