Hidden in the halls of the Fashion Institute of Technology in New York are historic textiles and glamorous garments, many of which hold secrets from years past.

Yet no matter how aesthetically unique or historically significant a particular piece of fashion may be, most visitors to the museum typically ask one question, said Emma McClendon, the museum’s associate curator of costume.

“People come and always want to know what size something is,” said McClendon, who organized the exhibition “The Body: Fashion and Physique,” about the history of the idealized body type in fashion, which is on display until May.

“Whether it’s contemporary or 19th century, they want to know what size it is or what size it would correlate to, or what measurement it is,” she said. “We as a culture, as a society, are obsessed with size. It’s become connected to our identity as people.”

This obsession fuels societal pressures to appear a certain way and to have a certain body type, particularly among young women, stemming from a cultural construct of the “ideal” body, which has in turn changed over time – as long ago as pre-history.

Thousands of years ago, sculptures and artworks portrayed curvaceous, thickset silhouettes. More recently, in the late 20th century, thin, waif-like models filled the pages of fashion magazines. Now, shapely backsides are celebrated with “likes” on social media.

To mark International Women’s Day, we explore how this “ideal” is ever-changing, forming a complex history throughout art and fashion – with damaging impacts on women who try to conform in each era.

Prehistory-1900s: A focus on full-figured silhouettes

Some of the earliest known representations of a woman’s body are the “Venus figurines,” small statues from 23,000 to 25,000 years ago in Europe.

The figurines – including the “Venus of Willendorf,” found in 1908 at Willendorf, Austria – portray round, pear-shaped women’s bodies, many with large breasts. Experts have long debated whether the figurines symbolize attractiveness or fertility.

In ancient Greece, Aphrodite, the goddess of sexual love and beauty, was often portrayed with curves.

A statue commonly thought to represent Aphrodite, called the Venus de Milo, depicts small breasts but is shaped with a twisted figure and elongated body, characteristic of that time period.

Artists continued to portray the “ideal” woman as curvy and voluptuous all the way through to the 17th and 18th centuries.

The 17th century Flemish painter Peter Paul Rubens was even the namesake of the term “rubenesque,” meaning plump or rounded, as he often depicted women with curvy body types.

To achieve this in reality, the corset became a popular undergarment among women in the Western world from the late Renaissance into the 20th century. It helped accentuate a woman’s curves by holding in her waist and supporting her bosom.

As societal views of a woman’s body changed over time, so did the shape and construction of the corset, also sometimes referred to as stays.

The 18th-century stay mirrored a cone-shaped silhouette, but by the 1790s, shorter stays emerged, resembling proto-brassieres, which complemented the new fashion trend of high-waisted dresses.

“There was an emphasis on under-structure to shape the body. That’s true for skirts as well,” McClendon said.

“Whether it be hooped or caged or padded, under-structures were worn around the lower body to create a specific volume,” she said. “In the 18th and the 19th centuries, the idealized fashionable body – so this is talking specifically about what’s promoted in the fashion industry itself – was much more curvaceous and much more voluptuous.”

In the 1890s, American artist Charles Dana Gibson drew images of tall, slim-waisted yet voluptuous women in illustrations for mainstream magazines, and these depictions of the new feminine ideal were referred to as the “Gibson Girl.”

Going into the early 20th century, the portrayal of women’s bodies in art was constantly evolving, as seen in French artist Henri Matisse’s oil paintings showing lithe, flowing bodies and then Spanish artist Pablo Picasso’s paintings showing plump, contorted nude bodies in vivid detail.

“Then, in the 20th century, there’s a very defined shift towards an increasingly young and increasingly kind of athletic and slender body,” McClendon said.

It remains somewhat unclear what triggered this shift, but the interest in thin bodies would continue well into the modern day.

1920s-’50s: Eating disorders – and a changing bust-to-waist ratio

The rise of the 1920s flapper reflected this shift toward the Western world desiring a more slim physique.

As slender women’s bodies started to appear in magazines In the mid-1920s, an epidemic of eating disorders also occurred among young women, according to some studies.

“The highest reported prevalence of disordered eating occurred during the 1920s and 1980s, the two periods during which the ‘ideal woman’ was thinnest in US history,” researchers at the University of Wisconsin-Madison wrote in a paper in the Journal of Communication in 1997.

The bust-to-waist ratios among women featured in the magazines Vogue and Ladies Home Journal dwindled by about 60% between 1901 and 1925, according to an analysis in a study published in the journal Sex Roles in 1986.

“Such findings would constitute empirical support for the hypothesis that the mass media play a role in promoting the slim standard of bodily attractiveness fashionable among women,” the researchers wrote. “Through this standard perhaps the eating disorders that have become increasingly common.”

By the late 1940s, that ratio climbed back, increasing by about one-third in both magazines, the study found.

Around that time, the fuller body types of pinup models and actresses like Marilyn Monroe grew in popularity, and the first issue of Playboy magazine was published in 1953.

The ratio then dropped again.

By the late 1960s, the ratio had returned to approximately the same level it was in the 1920s, the study found.

1960s-’70s: ‘A complete fallacy’ revealed

The historical shift from a rounded to a thinner body preference led to the rise of British fashion model Lesley Lawson, known as Twiggy, and other slender models.

They seemed to symbolize a shift away from the corsets and pinup girls of years past. Simultaneously, the “second wave” of the women’s rights movement began.

In 1960, the US Food and Drug Administration approved the birth control pill. In 1963, women’s rights activist Betty Friedan published her book “The Feminine Mystique.” In 1966, the National Organization for Women in the US was founded.

“People talk about the ’60s, even the ‘70s, as this moment when the woman’s body is freed,” McClendon said. “But that notion that women were all of a sudden completely free in their bodies after that point is a complete fallacy.”

Although women were no longer squeezing themselves into corsets, the media messaging and societal pressures to adhere to an “ideal” body still continued. That “ideal” was instead a very young and thin body type.

“Foundation garments were replaced by diet and exercise,” McClendon said.

What remained was the “notion that in order for your body to be truly fashionable, you had to probably change it some way,” she said. “You had to maintain it in some way.”

The incidence of severe anorexia nervosa requiring hospital admission rose significant during the 1960s and ’70s to reach a plateau, according to a study in the journal Current Psychiatry Reports in 2012.

1980s-’90s: The rise of the supermodels – and obesity

Though images of thin women continued to be mainstream well into the 1980s, there became more of an emphasis on strong, athletic and toned body types.

“We do see an interest in a fit, toned, strong body – still lean but athletic. So this is where you get the emphasis on those classic supermodels like Cindy Crawford and Naomi Campbell,” McClendon said.

Though there still was an emphasis on a thin body, there was also emphasis on a healthier and fitter body.

Then, by the ’90s, that emphasis shifted back to more skinny, waif-like body types.

“The term that gets so much associated with that decade is the ’90s is the moment of the waif,” McClendon said. “Kate Moss is the epitome of that. Her nickname was ‘the waif.’ She became a household name from Calvin Klein ads in the early 1990s.”

Anorexia nervosa was associated with the highest rate of mortality among all mental disorders during the 1990s, according to the study in Current Psychiatry Reports.

Around that same time, the World Health Organization began sounding the alarm about the growing global obesity epidemic.

Obesity means a person has too much body fat, and it can increase the risk of health problems including diabetes, heart disease, stroke, arthritis and even some cancers.

The prevalence of obesity sharply increased in the ’90s. An estimated 200 million adults worldwide were obese, and that number rose to more than 300 million by 2000, according to the WHO.

As images of obesity flashed across media screens as a part of public health outreach efforts, in contrast so did images of skinny models, McClendon said.

“We begin to see a stark divide in the way bodies are presented across the media, with extreme thinness celebrated in fashion imagery while larger bodies are highlighted as ‘unhealthy’ and bad in reporting on obesity. And we begin to judge our own bodies through the same binary lens,” she said.

So, it seems, the psychological impacts from that included impacts on body image.

2000s: Loss of self-confidence

Nearly a third of children aged 5 to 6 in the US select an ideal body size that is thinner than their current perceived size when given the option, and by age 7, one in four children has engaged in some kind of dieting behavior, according to a Common Sense Media report published in 2015.

The report, based on a review of existing studies on body image and media, also found that between 1999 and 2006, hospitalizations for eating disorders in the US spiked 119% among children under age 12.

In the United Kingdom, nearly a quarter, 24%, of child care professionals have reported seeing signs of body confidence issues in children aged 3 to 5, according to research from the Professional Association for Childcare and Early Years published in 2016.

Another study found that the incidence rate of eating disorders for people aged 10 to 49 in the UK rose from 32.3 per 100,000 in 2000 to 37.2 per 100,000 in 2009. Yet the peak age of onset for an eating disorder diagnosis in women was during adolescence, between 15 and 19, according to that study.

“When kids are entering adolescence, they’re developing their own identity and trying to figure out what’s socially acceptable so when they’re inundated with images of a particular body type in appealing scenarios, they’re more apt to absorb the idea that that particular body type is ideal,” said Sierra Filucci, executive editor of parenting content and distribution for Common Sense Media, a nonprofit organization focused on helping children, parents and educators navigate the world of media and technology.

Among a sample of 6,411 South Africans 15 and older, 45.3% reported being generally dissatisfied about their body size, according to a study published in the journal BMC Public Health in 2015.

Overweight and obese study participants underestimated their body size and desired to be thinner, whereas normal and underweight participants overestimated their body size and desired to be fatter, according to the study. Only 12% and 10.1% of participants attempted to lose or gain weight, respectively, that study found.

2010s: Embracing diversity

Since the start of the 21st century, there has been a shift toward celebrating diverse body types in the media and fashion. That trend appears to correlate with the use of social media, where diverse types are represented by everyday users online.

Of course, social media can also give some teens a negative body image. A Common Sense Media survey found that more than a quarter of teens who are active online stress about how they look in posted photos.

On the other hand, the rise of social media has allowed for real women to celebrate real body types. McClendon even called social media a “frontier for body-positive expression.”

“Over the course of the last 50-plus years, the American ideal has shifted from curvy to androgynous to muscular and everything in between,” Filucci said.

“As these ideals change, they are reflected and reinforced in the culture through media – whether it’s fine art or advertising billboards or music videos,” she said, adding that however those ideals are presented, they can still influence the body image of young women and even children.

In 2007, the first episode of “Keeping Up With the Kardashians” aired in the US, and ever since, the Kardashian sisters’ bodies have become a frequent focus of celebrity weekly magazines, ushering in new curvaceous body ideals.

In 2015, Robyn Lawley was the first plus-size model featured in Sports Illustrated’s swimsuit issue.

In 2016, fashion designer Christian Siriano featured five plus-size models in his show during New York Fashion Week. That same year, toy manufacturing company Mattel debuted a line of Barbie dolls depicting diverse body types, including curvy shapes.

Last year, reality show Project Runway, included models ranging from size 0 to 22 for the first time in its history.

As for the current state of beauty, some health experts are warning of the dangers of the “selfie” and social media culture as influencing body image, as the rise of Instagram and YouTube has allowed for the bodies of everyday people to be idealized, not just the bodies of supermodels.

Yet “when that body type is different from the one girls and young women have, they can be vulnerable to low self-esteem,” Filucci said, adding that parents can help children develop positive body images through role modeling.

“That means refraining from negative body talk both for themselves and others and speaking positively about their own bodies – especially emphasizing their body’s abilities like strength, flexibility, resilience, adaptability … rather than attractiveness,” she said. “Parents can also look for media that reinforces positive body images and avoids gender stereotypes.”

Correction: A previous version of this article miscalculated the incidence rates of eating disorders in the UK from 2000 to 2009.