Is living longer worth it?

If you have to live on a boring, restrictive diet?

UCLA evolutionary biologist John Phelan said he believes the diet may extend human life by a few years, but at a high price.

"It may increase your life span 2-3 percent if you eat this diet for decades," UCLA evolutionary biologist John Phelan, "but you'll be miserable the whole time."

Phelan studied caloric intake with mice and found they lived longest when they consumed barely enough to stay alive -- slashing calorie intake by 50 percent. However, their reproductive organs shut down, and the rodents became vicious.

"Usually when you work with mice you can pet them," Phelan said. "But any mouse on a restricted diet would try to jump out of the cage and bite you."

The Calorie Restriction Society, a Newport, N.C., nonprofit group dedicated to promoting the diet, also warns of health risks, including anemia, reduced bone mass, loss of strength and stamina, menstrual irregularity and slower healing.

Phelan said he doesn't believe the risks are serious, but said he's fond of telling people, "You may not live forever, but it'll sure seem like it."