Many of them are not yet out of their teens – yet they work long hours, eat very little and are under intense pressure to maintain their figure.
When hundreds of young models descend on the English capital for London Fashion Week twice a year, the culmination of all these strains can put their health at serious risk.
This year, however, the experience is likely to be even more demanding than the previous four, as a respite centre which offers them support and treatment during the event is to close.
Erin O'Connor has said that the Model Sanctuary, which she set up in 2008 to provide "discreet health guidance and educational support" to teenage models, would have to close during the showcase event next week because of rent issues.
The centre was launched amid controversy over London Fashion Week's refusal to ban dangerously thin models and a debate about the impact that the beauty "ideal" promoted by the fashion industry has on young girls' self-esteem.
Now, many leading models are speaking out over their concerns that the health of vulnerable young women is at risk.
Amber Anderson, 19, the face of Burberry and one of the models to have benefited from the Sanctuary, told The Independent: "It is a haven for so many models during the stressful show season.
"It is not unusual to work 18- or 19-hour days during Fashion Week without any space or time to yourself. I have been able to have a healthy, filling lunch, seek nutritional or exercise advice, have a massage to ease some of the stress or even have a nap in a room."
Anderson warned that the centre's closure "will greatly impact on the younger, more vulnerable models in the industry who need that support".
Ms O'Connor, 33, has appealed to the fashion industry to help save the project, which caters for 250 young women a day, many between the ages of 16 and 18 and gives them access to nutritionists and psychologists.
She said the Sanctuary, which was based in Covent Garden but operates on a "pop-up" basis during Fashion Week, needed a "workable venue and the security of long-term funding".
Jade Parfitt, 33, is a Vogue regular who made her catwalk debut in 1995. She has spoken out in support of the centre, saying that it represented an vital step forward for the fashion industry.
"It's imperative that young models today have access to facilities I wished were available to me when I first began my career. Initiatives like these, where fashion models' well-being are paramount are practically non-existent, when you take into consideration that many of the models working during London Fashion Week are aged 16 to 20 and are often travelling alone. The Sanctuary must indeed seem like a wonderfully safe place and should be given the opportunity to continue to develop."
Jo Swinson, the Liberal Democrat MP who campaigns against the misleading airbrushing of celebrities by the beauty industry, visited the centre last year. She said: "The Sanctuary plays a vital role during London Fashion Week. The fashion industry and the agencies that do so well out of using these models need to consider what they need to do to take on those responsibilities without the Sanctuary."
The MP met a delegation of models who are seeking industry-wide standards against exploitation through membership of the actors' union Equity. The union has produced a code of conduct for models, in partnership with the British Fashion Council, covering issues such as nudity, breaks and pay rates.
"In short, I am asking for greater support from the industry. It is my belief that this initiative is vital."