The fast track: trying to reduce your "body burden" may have the opposite effect.

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 for health reasons. To Vanzhov, fasting is a wonderful tune-up for mind and body. "I feel strongly that tasting should be part of everybody's health plan," he says.

Advocates like Vanzhov believe 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."

Relieving the Body Burden

Fasting and detox programs such as the Lemonade Diet are becoming more popular as Hollywood celebrities tout their weight-loss benefits. Many environmentally minded people also are interested in fasting as a tool for removing chemicals--the so-called "body burden"--from their system.

"Fasting isn't full, but you do feel healthy and energized a week or so after the fast is over," says Troy Reicherter, a history teacher and acupuncturist from California's Silicon Valley. "Fasting is very effective for a myriad of health problems and very important for spiritual well-being."

It's true that most of us store pesticides, mercury and dioxin in our fat. But medical experts say tasting is not the most effective way to shed pounds.

Who's Right?

When consumers use fasting as a way to lose weight or clean their insides, the science gets murky. Dr. 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 muscle and liver to provide glucose for the brain, and then tackle fat cells. This can overload the kidney and liver with toxic byproducts like ammonia and urea. It can also upset the electrolyte balance, leading to a heart attack risk. So your organs don't rest during a fast, explains University of California at Davis nutrition professor Sheri Zidenberg-Cherr. They are actually working overtime. "It's really the opposite of cleansing and detoxifying," she says.

The idea of a detox fast is a myth, Baratz says. "There's no so-called body cleansing that occurs," he says. "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."

Baratz also dismisses other detoxifying practices, such as sweating, enemas and colon cleanses. They are ineffective, he says, and, in some cases, dangerous.

A Little Help for the Body?

With all of the toxic threats in our environment, Vanzhov believes fasting is an easy and efficient way to detoxify. It's true that persistent chemicals like mercury and polychlorinated biphenyls (PCBs) stow away in our fat cells. But when those fat cells break down rapidly during fasting, the kidneys and liver might get overloaded. Instead, the chemicals could migrate to other parts of the body and cause trouble, says Sonya Lunder, senior analyst with the Environmental Working Group.

"Big pulses of chemicals going out of you may not be healthy" Lunder says. "Once things are in your body, there may not be a safe way to remove them."

Lunder says a woman of childbearing age should avoid fasting because it could release lead and mercury into the bloodstream. "That could be a dangerous thing for her fetus," she adds.

Little human research has focused on what happens when our bodies release toxins. Wildlife researchers at Cornell University's Center for the Environment noted a 293 percent increase in the concentration of PCBs in dogs that fasted for 48 hours. Could similar results happen with humans who go through rapid weight loss during fasting? It pays to be cautious, experts advise.

Doctors and dieticians 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 Blatner.

Meanwhile, other health professionals are concerned this new trend toward fasting may give people with eating disorders an acceptable excuse for starving themselves. While fasting for a day or two isn't a problem, says psychologist Maria Rago, director of Linden Oaks Hospital, an eating disorder program in Naperville, Illinois, during longer fasts, the body goes into a deprivation mode, which slows metabolism. "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."

Fast Avoidance

Certain people should not fast, including those with diabetes, women who are pregnant or nursing, infants or children, elderly people, anyone with irregular heartbeats and people taking prescription medications (which could be toxic to the kidneys during a fast). Anyone with a history of eating disorders or mental illness should also steer clear, health experts say. If you are young and healthy and want to try a prolonged fast, seek guidance from a doctor or health care provider first.

An alternative to fasting is prevention. It sounds boring, says Zidenberg-Cherr, but plain old moderation, exercise and clean living will go a much longer way to improving your health.

"Fasts or detox diets give people a false sense of security" says Blatner. "We need to eat lots of fruits and veggies and drink lots of clean water on a daily basis--it's more of a lifelong process." If we can limit our exposure to chemicals, we can prevent more toxins from entering our bodies in the first place, says Lunder.

CONTACTS: American Dietetic Association, [phone], www.eat right.org; Environmental Working Group, [phone], www.ewg.org; Organic Consumer Association, [phone], www.organicconsumers.org.