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Nicole Fernandez, a 25-year-old professional from Boston, has trouble finding clothes that fit. She's 5’4 and 105 pounds, and she’s been forced to find her clothing in the children's section her whole life.

“It’s hard for me to find suits and more professional clothes,” said Fernandez, who works at a law firm. “I’ve never been able to buy normal clothes because everything runs too big.”

One alternative would be to buy clothes in size 0, but “even size 0 is too large for me,” she said.

So with petite, short and/or very thin women like Fernandez in mind, some mainstream stores are going a step beyond: Now there's a size even smaller than 0. It's double zero.

“We made [size 00] available because of feedback from customers,” Gap Inc. spokeswoman Kimberly Terry said of the company's exclusive online introduction this spring of the size at Banana Republic (Gap Inc. is Banana Republic's parent company.)

“Regular women and especially petite women needed a smaller size,” she added.

But some shoppers say there should be nothing less than zero. They say size 00 is just the latest proof of "vanity sizing": stores cutting clothes larger so women can buy them in smaller sizes, and feel better about themselves by doing so (thereby making them more likely to buy).

"It's a very common practice," Tamara Albu, fashion design coordinator at Parsons School of Design, told FOXNews.com in 2002, when we first reported on the trend. "Designers make women feel they're a size 4 and they make a sale. It's a marketing trick."

Petite women say they've taken the brunt of this trend.

“It’s ridiculous because it ends up negatively affecting tiny women like me,” said Fernandez, who has tried the size 0 at stores like J. Crew, Banana Republic and even the 00 at Abercrombie & Fitch. “I have a friend who's normally a size 4, and fits into a size 0 in Abercrombie, while I’m shopping in the children’s section.”

In the 2002 article, we interviewed women who said they loved fitting into a size 6 when they knew very well they were more of a size 8, or a size 4 when they knew they were a size 6.

Other women are just as happy about it today.

“I like being able to go into a store and fitting into a size 10,” said Megan Connelly, 35, who lives in New York City. “I know that usually I’m a size 14, but it makes me self-conscious when I go into a high-end department store and they don’t have my size.”

Even men's sizes, which are considered more accurate because they are labeled in inches, often seem to be loosened to measure an inch larger than the advertised size.

“I’ve always been a size 32/33 around the waist,” said Geoff Sedaris, a 33-year-old from Cape Cod, Mass. But Sedaris says he buys pants in a size 30/31, even though he hasn’t lost any weight.

He also notices fluctuations in size from store to store.

“In some brands I can be a size medium, and in others I can even be a large or small,” said Sedaris.

For women, the fashion industry's fit model, or the model they use to size clothes downward and up, is a size 8 (the average American woman wears a dress size of 11-14, according to the U.S. Department of Health and Human Services.)

Gap Inc. says it uses industry sizing standards, except at Forth & Towne, where it uses a size 10 fit model, because the store caters to women size 2-20 — 10 being the middle of the size range. The company also uses a plus-sized fit model to design clothes for Old Navy's plus-sized department, which was unveiled in 2004.

"Stores are not just using one fit model anymore," Terry said.

While Terry says fits are consistent within stores, except for fluctuations due to different fits designed for different body types, clothes at Gap Inc.'s various stores might fit differently, even in the same size. Terry attributes this difference less to size and more about differing styles, silhouettes, cuts and fabrics.

“Each of Gap Inc.’s stores has a different typical customer, so size needs are different depending on the store. As we are designing clothes, we do keep our target customer in mind,” said Terry.

But even though size needs vary from person to person, people don’t always like to face the harsh reality of their actual dress size —- which explains why vanity sizing could be happening at mainstream stores.

“I would never buy clothes from a plus-size store,” said Connelly, who is aware that she could probably fit into clothes for plus-size women. “I like to dress nice and I like feeling good in my clothes, something plus-size clothing can’t do for me.”

Many women feel ashamed to shop in plus-sized stores and sections, even though upscale department stores, like Bloomingdale’s, now have plus-size sections.

“I was in Bloomingdale’s the other day, and I was looking for the men’s section, and ended up in the basement in the plus-sizes,” said Alex Stephens, a 29-year-old from Brooklyn, N.Y. “I was so embarrassed, I wanted to get out of there as fast as I could.”

With obesity growing in America, the plus-size market has grown by 50 percent in the past five years. In the last decade, all adult age groups in both genders have experienced an increase in overweight and obesity, according to the American Obesity Association. The prevalence of overweight is higher for men (67 percent) than for women (62 percent). The prevalence of obesity is higher for women (34 percent) than men (27.7 percent) as is severe obesity; women (6.3 percent) and men (3.1 percent.)

So even though most women fall into the plus-size category, only 12 percent said that plus-size stores are their “favorite” stores, according to a recent survey by Mintel International Group, a market research firm.

But with size 00 and plus sizes increasingly on the market in mainstream stores, it seems most women should be able to find their happy medium.