Cutting Calories To Live Longer

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Michael Sherman doesn't do anything halfheartedly. When he was a power lifter, he pushed his body to extremes.

"I'd like to have that body back again," says says Sherman.

Now that he's dieting, as CBS News Correspondent Bill Whitaker reports, he's pushing his body to extremes.

"I fill up the bowl, it's about 100 calories," he says.

The average American male eats more than 2,600 calories a day.

"Now I'm at 1,600 a day - about half the number of calories I think I'd like to eat," says Sherman.

He's part of the mushrooming calorie-restriction movement, based on the theory that the less you eat, the longer you live.

He fills up on salads, fruits and his own low-cal, high-nutrient mega-muffins.

"I'd rather have the extra years than the extra food," says Sherman.

It's not just pie in the sky. Scientists long have known that in primates and other animals, lifespan goes up when calories go down. It's only a theory, but they think semi-starvation somehow toughens up the body's cells.

For the first time, in three separate government-funded trials, researchers are testing the theory on humans. So far the results have been promising: lower blood pressure, cholesterol and lower chance of diabetes.

Brian Delaney, president of the Calorie Restriction Society, says such results are making converts.

"So people are starting to realize it's worth trying, especially people with heart disease or cancer in their family," says Delaney.

It's not for everybody. But more and more extreme calorie watchers from Southern California to Harvard Yard, share a hunger for life.

"If I could make it to 100 that would be great," says Kenton Mullins. "I do experience hunger on a daily basis."

"I want to do some good in the world and the longer that I have to do that, in whatever way possible, the better," says Hillary Catherine Robinson, a Harvard law student.

But adding two to three decades to life?

"And the thing that I think that is most important is exercise," says Dr. Michael Alderman, of the Albert Einstein College of Medicine. "To exercise adequately, you have to consume a fair number of calories."

Sherman exercises, but is counting calories.

Thought we're all going to die, Sherman says, "dying later is better than dying earlier."

And, he's counting on having the last laugh.