Michael Lowe, a Philadelphia psychologist who specializes in eating disorders, said while weight loss is usually the first sign of anorexia, the vast majority of diets "do not spin out of control."
And, for those predisposed to anorexia, images of skinny fashion models and television stars can have a "devastating effect" on young girls.
In the case of television shows like "Survivor" and "The Biggest Loser," where contestants can experience large weight losses, anorexia could "theoretically happen," said Lowe. "Anyone running a show where weight loss is a part of it, it increases the responsibility and they need to manage the risk."
CBS said it has a "tremendous track record" monitoring its contestants, taking their blood pressure and gauging their health.
When things go wrong, viewers see it on camera. In 2006, Gary Stritesky was medi-vacced out of Fiji. In Australia, contestant Michael Skupin blew out a fire, inhaled the smoke and fell into the flames, requiring medical attention.
But, Geoffry White, media psychologist and consultant to reality TV producers, told ABCNEWS.com that the network has no responsibility for cast members who put their health in danger.
"The cast signs a consent agreement acknowledging the network will be held harmless for pretty much anything that happens to them," he said.
Still there can be an insidious pressure to stay on a show, despite suffering health effects. The network must allow contestants to leave the show, but few do, White said.
"We know from 30 years of psychology research on conformity that practically no one will leave or 'disobey' the implicit pressure," he said. "They're psychologically trapped. It's a little like being in a cult. The celebrity pressure is enormous."
Of course, weight loss on a show like "Survivor" does not always signal anorexia, according to Edward Abramson, a California psychologist and diet specialist.
"There may be stresses associated with competition and other psychological variables that are quite powerful, but they don't meet the criteria for body image issues," he said.
Depression and anxiety can also cause weight loss. Yates may be "responding to the stress of participating and being on television," he said.
Abramson, too, worries about the message that fitness shows like "Survivor" send to young girls struggling with their body images.
"Clearly the overemphasis on a slender physique as prerequisite for success in dating, marriage and life is really kind of ridiculous," he said.
Suffolk University, which graduated Yates in 2003, is proud of its thin, but tough alumna.
"Courtney is very popular," said public affairs officer Tony Ferullo. "We appreciate what she has done for the school. It's a very difficult challenge for these people and the fact that she's gone this far is a credit to her perseverance."
The school featured her in its alumni magazine and has fed progress reports to local newspapers. Now, a month away from the Dec. 16 finale and a shot at the $1 million jackpot, Yates is looking like the college's mascot.
"Courtney represents our alumni well," said Ellen Solomita, director of the university's alumni association. "She's hardworking, pull up your boot straps, and that's who we are."
It also helps to have a fast metabolism on a show like "Survivor," said Solomita. "You don't have a bag of Doritos right there with you."
"She is a survivor in a positive, not a pejorative, sense," said her English professor Connolly. "She has developed a good strategy."
So, too, has the television publicity machine.