Anaheim, CA - It may easy to live longer - just lay off the pizza and hamburgers, experts said.
Experiments on mice - and one unplanned experiment on people - show that following a lifetime diet about 30% lower in calories than the average American diet can set in motion physical responses that help the body resist ageing, the researchers told the annual meeting of the American Association for the Advancement of Science.
Dr. Roy Walford of the University of California Los Angeles was among eight men and women sealed inside Biosphere 2, an experiment aimed at determining whether humans could ever live in space.
From 1991 to 1993 they were locked away from the rest of the world, having to grow every bite of food, generate their own air supply and recycle all their water. But they ran low on food and Walford saw the perfect opportunity to run an experiment.
He knew of studies in mice that showed mild starvation caused them to live longer. Perhaps, he thought, the same was true of people.
As the Biosphere team members ate less, Walford observed their body statistics. "The men lost an average of 18% of body weight, the women 10%,” Walford told a news conference.
Blood pressure fell on average by 20%. Indicators for diabetes, such as blood sugar and insulin levels, decreased by 30% on average.
Cholesterol levels fell from an average of 195 - considered normal - to 125, considered extremely healthy.
It would take years to tell if humans really live longer on such a diet. Most of the Biosphere team, with the exception of Walford, have since gone back to eating normal American diets.
But since the physiological effects of mild starvation were the same in mice and people, Walford thinks it follows that the anti-ageing effects would be the same, too.
Other experts think they are closing in on an explanation of why steady dieting might benefit the body.
Gentle starving may start up a stress response that rescues cells from dying, said James Nelson of the University of Texas Health Sciences Centre. Cell death also is an important component of ageing.
Nelson said several experiments in creatures such as the fruit fly showed that the same genes that become active when an animal fights off stress such as a toxin, become active when calories are restricted.
In mice, a hormone similar to the human corticoid stress hormone is elevated by chronic food restriction, he said. He would like to see if that is also true in humans.
Starved mice not only have healthier hearts, but lower instances of cancer and autoimmune diseases, Walford said. They also stay fertile much longer than normal mice.
People who want to try this low-calorie diet cannot simply eat less, but have to eat better, Walford said.
"Basically it is what you would assume is a very wholesome diet - a whole lot of vegetables, some fruits, whole grains, a little bit of meat. It's not that mysterious.”
The key is to make sure you are getting enough vitamins and other nutrients, while losing a little weight, he said.
How much that adds up to will vary from person to person.
In the Biosphere, each person got 1,800 calories a day. But they were working hard, growing rice, tilling fields and doing other chores.
Walford and Nelson both noted metabolism varies from person to person.
"One 120 pound (50 kg) woman will maintain her weight on a 2,500 calories a day diet but another will maintain her weight on 1,700,” Walford said.
Walford was so impressed by the findings that he keeps to a disciplined restricted-calorie diet.
But Nelson admits he does not. "Probably for the same reasons that most people have difficulty doing this sort of thing,” he laughed. "I just happen to be graced with genes that make me skinny.”
Meat Industry Insights News Service
P.O. Box 553
Northport, NY 11768
Phone: 631-757-4010
Fax: 631-757-4060
E-mail: sflanagan@sprintmail.com
Return to Home Page