Scientists Gain Insights on Life-Extending Diet

(April 15) -- The perils of overeating are no secret. Scientists, writers, activists and politicians have been warning the public for years that carrying excess weight increases your risk of heart disease, diabetes and more. But researchers have also been exploring the health ramifications of the opposite approach to the dinner plate -- diets centered on calorie restriction. Numerous studies have shown that limiting calories can lead to longer, healthier lives in yeast, insects and several animals.

Now, according to a new paper in Science, experts are starting to understand the biological mechanisms at play and closely monitoring the results of limiting food intake in people, too. "Calorie restriction is extending lifespan, and extending healthy lifespan, by preventing many chronic diseases in yeast, worms, mice and monkeys," Luigi Fontana, a scientist at the Washington University School of Medicine in St. Louis and one of the study's co-authors, tells AOL News. "For the first time, we are basically trying to move from the typical animal models of longevity to humans."

The new paper isn't solely about skimpy diets. Fontana and co-authors Linda Partridge of University College London and Valter Longo of the University of Southern California also report on the life-extending benefits of certain genetic modifications, which limit activity in key molecular pathways. Eating less, it turns out, ends up affecting the same biological processes.

Fontana says the health benefits of calorie restriction probably stem from our evolutionary past, when humans were more likely to suffer through periods of starvation. We may have evolved mechanisms to protect our DNA during these sparse periods. Today, the scientists are essentially stimulating these built-in protections through forced calorie restriction or genetic manipulation. In the animal models the results are particularly striking. "Basically, these animals, because of these protections, they are living longer."

That said, the findings from yeast, worms, mice and monkeys don't translate directly to people. The fact that some simple organisms live two to three times longer on limited diets doesn't mean we will all see the year 2200 if we start subsisting solely on lettuce. Giving up food all together and living on air, a la the breatharians, will not help either. Fontana says that proper nutrition is essential and cautions that there is no universal life-extension diet. In fact, it's more likely that there is an optimal life-extension diet for each person based on age, sex, genetic background and other factors.

Fontana has been tracking a group of people sticking to nutrient-rich but calorie-restricted diets for the last 10 years in hopes of learning more about these processes. He looks at how they have adapted in terms of their physiology, metabolism and more. He's also aware that in our consumption-focused society, such strict regimens might not catch on. Now that scientists have begun to detail the biological mechanisms involved with calorie restriction, though, he says it might be possible to develop medicines or other interventions that deliver the same health effects to people who can't cut out the extra helpings.

His goal isn't to extend lifespan to 150 years, but to enable people to stay healthier longer and to ward off the age-related diseases that plague humans later in life. And he cautions that despite the recent progress, he is not quite there yet. "There is a lot of work to be done," he says. "We are just at the beginning."