Khurram Hashmi has drastically cut the calories he consumes eating mostly salads and raw vegetables in the hopes of living a longer, better life.

But he's hungry almost all the time. "That's something for me that has never gone away, but it is easier to accept now," says Hashmi, 37. He says he used to cheat, but not anymore. The hunger tells him that the diet's working, he says.

The diet is not for everyone: Hunger and low libido are facts of life for Hashmi and other followers. But they put up with what amounts to a near-starvation diet because a slew of studies has shown that mice and other lab animals that eat a very low-calorie diet live about 30% longer than they otherwise would. These studies also suggest that the diet protects the body from age-related diseases such as diabetes.

"It is the only nutritional regimen thought to retard aging," says Richard Weindruch at the University of Wisconsin-Madison. His studies have suggested that middle-aged mice can start the diet and still get the longevity benefit.

Heart markers

In an ongoing study of monkeys, Weindruch has found that the very low-calorie diet seems to shield these animals from type 2 diabetes, a common disease of old age. None of the monkeys on the diet, which are now about 70 in human terms, has developed diabetes. Monkeys fed the usual lab chow already are developing this life-threatening disease, he says.

But will the diet work for humans? Hashmi and the 1,800 other members of the Calorie Restriction Society, a non-profit group that advocates the diet, believe it will.

Hashmi, who runs his own Internet marketing business from his home in Gardena, Calif., consumes about 1,800 calories a day, far below the 2,400 consumed by the average American man. He weighs 129 pounds, which on his 5-foot-11 frame looks gaunt. He says the diet gives him enough energy for an active life that includes a 4-mile-run every other day and 50-mile bike rides once a week.

"I have lost some of the fat on my face," he says. "People think that it makes you look older."

But he's willing to put up with that because he believes the diet will slow his aging and make him look younger in the future.

More scientific evidence to support Hashmi's choice arrived in April 2004.

Luigi Fontana, a researcher at Washington University in St. Louis, and his colleagues reported results from a small study of people who had been following the diet for up to 15 years. All 18 people on the diet were members of the Calorie Restriction Society. They reported consuming 1,100 to 1,950 calories a day, depending on their height, weight and gender.

The team collected blood and measured biomarkers that put people at risk of cardiovascular disease. They found that the people on the diet, who were 35 to 82 years old, had greatly reduced their risk of clogged arteries, which can lead to heart attacks and stroke.

For example, when the team measured a type of fat in the blood that often signals high cardiovascular risk, they found that the people on the diet had levels that were lower than 95% of people in their 20s. The average blood pressure for people on the diet was 100/60 about what is expected for an average 10-year-old, Fontana says.

It comes with a cost

The study, which appeared in the Proceedings of the National Academy of Sciences, still doesn't offer any proof that the diet will push the human life span past normal limits.

Skeptics say flat-out it won't work the way it does in mice.

John Phelan, an evolutionary biologist at UCLA, constructed a math model of the diet and found that people who drastically cut calories starting very early in life (and never cheated) might live four to five years longer. The diet won't push the maximum human life span much past 120, he says.

To Phelan, the diet's small benefit doesn't begin to make up for the downside. He says mice on the diet, which provides food at near-starvation levels, appear cranky. "If you take the lid off the cage, they immediately bite you," he says.

And in addition to constant hunger, followers say the diet can lower their libido. Hashmi, who is single, says that although his libido is low for someone his age, he expects to maintain an interest in sex throughout his life, into old age. He says he was cranky when he first started the diet five years ago. But Hashmi says his mood quickly stabilized after his body adjusted to fewer calories.

Phelan once considered following the diet himself but changed his mind when he plugged the numbers into his math model. "It's a starvation diet for decades with very little payoff," he says.

Following the diet also can be risky. People who cut calories but eat mostly junk or highly processed food run the risk of malnutrition, Fontana says.

People don't have to starve to get a benefit from the diet, says Brian Delaney, president of the Calorie Restriction Society. He says most Americans would gain by cutting out unnecessary calories: They'd lose weight and if the studies on rodents are correct they might age slightly more slowly.

That's what Hashmi is banking on. And that's why he now carefully follows his diet. He considers everything he eats whole-grain muffins, vegetables and other foods loaded with nutrients.

To Hashmi, the effort is worth it. He is betting the diet will result in a longer life.

"If I can live to be 120 that wouldn't be bad."

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