Could a 5-Day Fasting Diet Prolong Your Life?

Calorie restriction may be a key to longevity—as long as you can stick with the plan. REUTERS/Mike Blake

Starvation probably doesn't sound like a key to living well into old age. But as strange as it seems, calorie restriction, done intermittently, appears to be one of the gateways to lasting long-term health.

The concept has already been proved effective in mice, rats, dogs and monkeys. However, very limited research has been done to evaluate the health impact of calorie restriction in humans. In animals, calorie restriction is associated with longevity, decreased risk for cancer and inflammatory diseases and lower cognitive decline. The challenge has been to translate the concept to the real world in which humans need to eat to get through the day.

A new study tested out a modified version of the concept on humans. Researchers at the University of Southern California have designed what they call a "fasting mimicking diet" that provides all the benefits of starving yourself...with a little less starvation.

The plan lasts for five days a month, with a cycle that's repeated for three months. On Day One, a dieter eats food from the prescribed plan that totals 1,090 calories (10 percent protein, 56 percent fat, 34 percent carbohydrates). On Days Two through Five, dieters consume just 725 calories (9 percent protein, 44 percent fat, 47 percent carbohydrates).

People on the diet ate vegetable soup, energy bars, energy drinks and low-calorie snack chips, and drank a lot of chamomile tea. They also took vegetable-based dietary supplements. On non-dieting days they ate normally.

"It's all stuff you can safely eat without being too concerned. It's not the same as having a great steak," says Jan Vijg, chair of the Department of Genetics at the Albert Einstein College of Medicine. "But at least you're not hungry."

It may sound gimmicky, but Vijg says existing science already backs up the claim that the plan could effectively improve human health and prolong life. In humans, the diet provided a number of physiological changes that could reduce risk factors for age-related conditions such as reduced blood glucose and insulin levels.

The study, published in the journal Cell Metabolism, involved 19 participants on the plan, who completed three cycles of the fasting mimicking diet, and 19 participants who ate normally. Before testing the plan on humans, the researchers tried it out on yeast and mice.

In adult mice, they implemented the diet twice a month for four days in a row. The mice on the diet lived up to seven months longer than those not on it. These mice also had decreased incidences of cancer and other diseases and performed better on memory and cognitive tests. In autopsies, the researchers also discovered their organs were smaller, which they say suggests less inflammation in the body and leaner body composition.

Vijg wasn't involved in the research, but he says scientists generally believe this phenomenon may be related to survival of the fittest. "The normal situation in nature, of course, is you never have enough food," he says. "We believe that during evolution this mechanism started to emerge as a survival mechanism."

In essence, fasting has the ability to improve stress response on a cellular level. A person on this program is likely to lose weight over time, but researchers say better health in old age is the real benefit. With the right marketing, Vijg believes a fasting mimicking diet could become the next commercially branded diet craze, like Atkins or Paleo. However, it could also have some practical applications in a medical setting. A physician could prescribe the diet to a patient for a specific amount of time before surgery, chemotherapy and other types of treatments and procedures that are known to cause trauma and stress to the body.

More research would be needed, but the science already indicates that such a diet may help speed up a patient's recovery time, Vijg says. "To me, that would be the immediate application of it: to increase your cells' immediate resistance to stress."