NEW YORK — In the lobby of 275 W. 39th St., in the heart of the Garment District, a clutch of towering teenagers stand waiting for the elevator. Their tiny doll-like heads bob and swivel atop reed-thin bodies. They are hipless and cleavage-free, but with the luxuriously long, slender legs of a racehorse. They are about to be inspected like thoroughbreds.

The young women are headed to the 11th-floor showroom of womenswear designer Tracy Reese, who is casting her fall 2007 fashion show.

Along with a casting director from Los Angeles, who has already winnowed the pool of models down from almost 100, Reese will see some 60 young women. She will select about 20 to walk her runway under the tents in Bryant Park. Similar scenes unfolded across the city as Seventh Avenue prepared for the opening of New York's fashion week, which began Friday.

This real-life version of "America's Next Top Model" is unfolding while the industry engages in vigorous hand-wringing over whether the models it uses are dangerously thin, perhaps even anorexic.

Consumers have long grumbled that girls in their gangly adolescent years are held up as the ideal of beauty for women who are long past their 30th birthdays. But over the past decade, models have been shrinking. The average runway sample has gone from a size 6 in the early 1990s to a size 2, the current standard. In that same time, models have been asked to show less personality on the catwalk. The industry has exchanged the ballerina carriage of the sparrowlike Shalom Harlow in the 1990s for emotionless stickpins.

Last year, two underweight South American models died. City officials in Madrid set a body-mass minimum for women on the runways there. Milan announced it would develop a nationwide campaign to prevent anorexia. With the media spotlight on New York, the Council of Fashion Designers of America, which represents many of the designers — including Reese — who will show their collections over eight days, offered a six-point health initiative intended to protect models.

The plan includes workshops to educate the industry on eating disorders, a minimum age of 16 for runway work, and the availability of nutritious food during fittings, which often run late into the evening. On Monday the council hosted a panel discussion — with a nutritionist, personal trainer, model and designer and CFDA President Diane von Furstenberg — to elaborate on its initial proposals.

PROTECTING YOUNG GIRLS

"I think our most responsible guideline was the age requirement," says Steven Kolb, executive director of the CFDA. "One agent called and said he had two girls, one was going to be 16 the day after fashion week ended and another was a month shy of her 16th birthday, but her mother would be accompanying her. The fact that they even thought to call is positive."

"A younger girl is still going through a lot of changes in her body. And then the industry says, 'We like you like this.' As she becomes bigger and fuller, there's nothing she can do," Kolb says.

Eating-disorder specialists have not been impressed with the CFDA initiative. The problem isn't so much age or the fashion industry's familiarity with eating disorders. It's the size-2 ideal.

"What we know is there are people out there who are more or less predisposed to eating disorders. People who are more predisposed are more sensitive to their environment," says Cynthia Bulik, a psychologist and eating-disorder expert in the School of Medicine at the University of North Carolina at Chapel Hill. "Genes load the gun and environment pulls the trigger. And the fashion industry is sitting there with its finger on the trigger."

Bulik notes that designers seem more interested in preserving their right to make aesthetic choices than in dealing with the broader impact of them.

For the fashion industry, where race is often regarded as little more than a paint chip, body image is just another way of describing the season's silhouette.

In the aesthetic of designer Narciso Rodriguez, for example, hips are an asset. His models are thin, but not emaciated. "The girls I like are curvaceous," he says.

"There have been moments when I've built a collection where that sort of (skinny) frame is better. When I worked at Calvin (Klein), it was desirable that clothes hang from the collar and shoulder bones," says Rodriguez, who showed his signature collection last evening. "With super-skinny clothes, you want super-skinny girls. The sad thing is, that has a impact."

A diverse range of models has shown up to Reese's model call: white, Asian, black. On average, they are about 5-10 and 33-23-34. "Some of them you can tell it's small bone structure," Reese says. "Some just look hungry."

Reese looks for models who are well-proportioned; she doesn't want a young woman who is all legs and no waist. Like most other designers, Reese's runway samples are a size 2 or 4. They were a 6 when she started out.

A model walks into the casting with an elegant face and short, dark hair. "She's beautiful," Reese says quietly, "but she's less than a 0." The model ducks behind a screen and slips into a pair of trousers. They hang on her like sweat pants meant for someone twice her size. She also has tiny scars running up both arms. Reese notices them and intimates that she believes they're indicative of "cutting." She does not hire the model.

Another young woman wears black leggings and a striped cardigan. Her hipbones protrude beneath her woolly top. A pale blonde in narrow gray jeans and high boots stands awkwardly before the judges. Her thin hair hangs lank around her face; she is at least 20 pounds lighter than the other girls in the room. Neither model is hired.

Only one model arrives who is substantially larger than the new standard. She looks strangely ... normal. Could she be a size 6? Ultimately, it doesn't matter. She's too much of a novice. And she's a stomper.

This is the designer's dilemma: Because the size-2 models are the most popular, they have the most experience. The size-6 model is inexperienced. Hire her for aesthetic reasons and she'll stand out not only because of her size but also because she isn't as qualified.

It's hard not to notice that as the models have gotten thinner, the general population has gotten fatter. "The extremes are getting more extreme. People who are already large are getting larger and on the other side is this shrinking ideal," Bulik says. "That makes the gulf between the actual and the ideal even bigger and that makes self-esteem plummet."

Consider this: When Reese opened her first free-standing store last spring in New York, she offered sizes 2 to 12. She was prepared to expand to 14. Instead, the demand was for size 0. Her best-selling size is 4.

People buying designer clothes are super-thin. In the meantime, companies catering to the mass population, such as Coldwater Creek and Chico's, offer sizes 14 and 16 in lieu of 0 and 2.

Those in fashion offer this reassurance: The pendulum will swing the other way. In due time, the industry will celebrate a more athletic ideal. This is discussed as if it will magically happen — as if an outside force beyond the control of the industry will determine when that shift will occur.

But change may be a long time coming. In advance of fashion week, a promotional package went out to editors. Inside was a bright red box labeled "NV." The contents? A "rapid weight-loss beauty pill."