"Heavy Burden" will be broadcast Saturday at 8 p.m. ET/PT.
Supermodel Carol Alt swears by a "raw" food diet, which basically includes fruits and vegetables that are grown organically and not cooked. "My weight maintains itself," she says. "Sometimes I actually have to eat a little more to put weight on."
Alt says cooking food destroys enzymes and minerals and claims that since she's been on the raw diet, "I've never taken another aspirin. I've never taken another Tums. I never had another sinus infection."
But University of Southern California food scientist Roger Clemens disagrees. He says that cooking actually liberates nutrients so that the body can absorb them properly.
Correspondent Bill Lagattuta follows three women who want to get healthy and lose weight through a 21-day program called "de-toxing," a strict vegetarian diet that emphasizes raw food, and is designed to cleanse the body of toxins.
Lagattuta speaks to "de-tox" program developers John Wood, a nutritionist, and Richard DeAndrea, a medical doctor.
"This is a harmless technique that has been done for thousands of years," says DeAndrea, who claims that people need to detox now more than ever: "There's over 7.1 billion pounds of chemicals and neurotoxic waste dumped into the air, food and water."
However, Peter Pressman, a clinical medicine teacher at USC, says it's all a myth: "If you find that this works for you and you do it again and again...you're likely to become deficient in many vital nutrients. You're gonna begin to break down."
Plus, Anchor Lesley Stahl and ABC's Barbara Walters share their fitness secret. They work out just once a week for 20 minutes with fitness guru Adam Zickerman. His program, "Power of 10," is based on very slow weightlifting. Zickerman says no cardio is needed. However, several health organizations disagree, recommending at least five to six days of moderate exercise per week. Correspondent Troy Roberts puts "Power of 10" to the test.
And, one third of all women with eating disorders are over the age of 30. These disorders, which commonly affect teenage girls, are killing thousands of older women each year. Correspondent Peter Van Sant reports on Pat Melillo, a 55-year-old homemaker from Long Island, N.Y., who began suffering from stomach problems five years ago. When Melillo's doctor recommended a low-fat diet, she took his advice to a dangerous extreme. She became obsessed with what she thought was the perfect diet.
Melillo became anorexic and had to be hospitalized when her weight dropped from 110 pounds to 73 pounds. She became so malnourished that she developed a hole in her lung and was at risk of having a heart attack. Dr. Joseph Donnelan, who treated Melillo, says, "So many people think that eating disorders are just a bunch of teenage girls who wanna be thin. ... It has nothing to do with eating. ... It's about self-esteem and self-confidence and how you feel about yourself."
Don't miss "Heavy Burden," Saturday, Nov. 29 at 8 p.m. on 48 Hours Investigates.