Once a year, Filip Vanzhov shuts his fridge and doesn't open it for seven days. Vanzhov, a naturopathic physician from British Columbia, isn't on a diet. He abstains from food as a tune-up for mind and body. "I feel strongly that fasting should be part of everybody's health plan," he says.
Advocates like Vanzhov believe that fasting gives the body a break from the work of digesting food all the time, allowing it time to heal. "The body can do amazing things," he says. "We don't realize how much we overload our systems."
Many environmentally minded people are interested in fasting as a tool for removing chemicals from their systems. And it's true we store pesticides, mercury, and dioxin in our fat. Fasting and detox programs such as the Lemonade Diet are also becoming more popular as Hollywood celebrities tout their weight-loss benefits.
But the science of using fasting as a way to lose weight or clean your insides is murky. Robert S. Baratz, a Boston-area internist and president of the National Council Against Health Fraud, does not see the value in fasting. "There's no magic about this--you're talking about starvation," he says.
When people fast, their bodies break down protein from their muscles to provide glucose for the brain, and then they tackle fat cells. This can overload the kidney and liver with toxic by-products like ammonia and urea. It also can upset electrolyte balance, leading to a heart attack risk. Your organs don't rest during a fast, explains Sheri Zidenberg-Cherr, a nutrition professor at the University of California at Davis. They're actually working overtime. "It's really the opposite of cleansing and detoxifying," she says.
The idea that fasting detoxifies the body is a myth, according to Baratz: "There's no so-called body cleansing that occurs. . . . The body doesn't work that way." Dawn Jackson Blatner, a spokeswoman for the American Dietetic Association in Chicago, agrees. "We were born with our own detoxification systems: our liver and kidneys."
Little research has focused on what happens to humans when our bodies release large amounts of toxins during fasting. Researchers at Cornell University's Center for the Environment noted a 293 percent increase in the concentration of polychlorinated biphenyls (PCBs) in dogs that fasted for just 48 hours. Could the same thing happen to us? It pays to be cautious, experts advise.
"Big pulses of chemicals going out of you may not be healthy," says Sonya Lunder, a senior analyst for the Environmental Working Group, a nonprofit research organization based in Washington, D.C. "Once things are in your body, there may not be a safe way to remove them."
Doctors and dietitians say they might endorse fasting if they could find some objective, credible proof that it's safe and effective. "If there is enough evidence in five years, I'll be recommending this to people," says Jackson Blatner.
Meanwhile, other health professionals are concerned that the trend toward fasting may give people with eating disorders an excuse for starving themselves. While fasting for a day or two isn't a problem, the body goes into a deprivation mode during longer fasts, says psychologist Maria Rago, clinical director of the eating disorder program at Linden Oaks Hospital in Naperville, Illinois. "Fasting has also been universally shown to set people up for binge eating," Rago says. "If they're fasting, they might not be able to help overcompensating for that with a binge."
People with diabetes should not fast, nor should women who are pregnant or nursing (fasting could release lead and mercury into the bloodstream), infants, children, elderly people, anyone with irregular heartbeats, and people who take prescription medication (which could be toxic to the kidneys during a fast). If you are young and healthy and want to try a prolonged fast, seek guidance from a doctor or other health care provider first.
Or you might consider prevention. It sounds boring, says Zidenberg-Cherr, but plain old moderation, exercise, and clean living will go farther toward improving your health than fasting.
"Fasts and detox diets give people a false sense of security," says Jackson Blatner. "We need to eat lots of fruits and veggies and drink lots of clean water every day--it's more of a lifelong process." And limiting our exposure to chemicals prevents more toxins from entering our bodies in the first place, adds Lunder.
Reprinted from E (May/June 2007), the environmental magazine published by Earth Action Network Inc. Subscriptions: $29.95/yr.
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