Wednesday, August 31, 2005

Cranky, hungry rodents

Most people have probably heard that deliberately underfeeding mice and other animals can have a dramatic effect on increasing their life span. Some people have been known to try it too. Problem is, according to this story, it seems it doesn't work to any very significant degree for human, 'cos we aren't rodents. To quote:

"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." "

But for humans:

"Their mathematical model shows that people who 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."

What's more, just because a rodent lives longer doesn't necessarily mean they're enjoying it:

"The rodents placed on severely restricted diets bit people who tried to hold them, and had an unpleasant demeanor, unlike the more docile animals given more "normal" amounts of food, Phelan said."

And why does it work well for rodents but not humans?

""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."

Makes sense.

I will go enjoy my moderately sized dinner tonight, and I probably won't feel like biting anyone either.

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