That's the question of the moment in fashion capitals across the world. Here are some of things people within the industry have been saying about the debate.
New York Fashion Week came and went last month with little talk on the issue, other than a few fashion-show regulars noting that they were seeing even more ribs and vertebra than usual.
Meanwhile, Madrid banned ultra-thin models from appearing in its Fashion Week. The British culture secretary urged London to do the same, but organizers rejected her plea, saying that designers deserved creative control of their catwalk.
It was announced that in Milan, Italy, models will soon have to present a health certificate to appear on the runway, just like athletes need to do before playing competitive sports.
Catwalkers -- now mostly an anonymous group of models since Daria Werbowy, Carmen Kass and Karolina Kurkova seem to eschew the runway in favor of ad work -- are the primary target.
"The place you tend to see very thin is the runway, and models on the runway tend to reflect trends in fashion design," says Katie Ford, CEO of Ford Models. After a parade of "womanly" models in the 1980s, "The counter-fashion trend in the '90s was grunge. That was a look that appealed to very young people, it was almost the opposite of womanly. The models were androgynous, very thin -- heroin chic, which ended pretty quickly because people rebelled against it -- but on the runway, some of that stayed on."
While the debate over runway models has created lots of headlines, runway modeling is only a small chunk of the business. Catalogs, advertising and magazine editorial pages spend far more money on models -- and they also are seen by a much bigger audience.
Those models are still slimmer than most U.S. women, but they are more likely to be fit.
Witness some of the nation's most popular models, including Naomi Campbell, Heidi Klum and Gisele Bündchen. They're all pop culture queens, and no one could say they look hanger thin, even though they're certainly slim and trim. "Womanly" superstars of the '80s and '90s -- Linda Evangelista, Claudia Schiffer and Christy Turlington -- are also still going strong.
"That very thin look isn't for us," says Rachel Di Carlo, spokeswoman for American Eagle Outfitters. She says with teens and young women as the brand's target customer, the company is more interested in models who look healthy and energetic.
There is movement to broaden the definition of "beautiful." Dove famously started to use "regular" women as models two years ago, and now is set to be honored by the Cosmetic Executive Women, a beauty industry group, for its Campaign for Real Beauty.
"Self-esteem is closely linked to body image," says Philippe Harousseau, vice president of Dove's North American skin care unit. "This was about raising self-esteem, especially with younger girls. It's extremely damaging for younger girls who suffer from body-issue self-esteem issues. It can keep them from realizing their full potential in life."
Dove also sought to draw men into the debate, airing a TV commercial full of teenagers discussing their insecurities during the Super Bowl. The result? Dads started visiting the company's online chat rooms to weigh in.
For the first time in recent memory, a top designer -- Dolce & Gabbana, in this case -- used a plus-size model in an editorial campaign. Crystal Renn appeared in fall ads.
While the industry tackles these issues, it also points out that no one should confuse the runway with reality.
"In magazines, they are icons of what is a fantasy," said Katie Ford. "Anything that's entertainment is a fantasy. You see people jump off buildings in the movies, but you wouldn't do that. Anytime people start incorporating fantasy and reality, you have a huge issue."