Rosie Nelson, the model whose change.org petition demanding better care for women and men in the fashion industry received 114,000 signatures, spoke to the all-party parliamentary group on body image.
She was joined by Hayley Hasselhoff, representatives from agencies for both traditional and plus size models, doctors and a representative from the model's union at Equity.
"Every time I went into an agency, I was prodded and poked, and measured with a tape measure. I used to dread it," Nelson said.
Rosie Nelson outside 10 Downing Street on Tuesday 1 December
"Friends at shows saw models who fainted and had to be dragged off the stage, quickly replaced by another girl," Nelson added.
"At one stage, all I ate was fruit and vegetables, nothing else. One girl I knew only ate popcorn."
The committee, which is chaired by the Conservative MP Caroline Nokes, heard arguments about whether the UK should follow impose rules to prevent models with eating disorders being used on catwalks and in fashion shoots.
Hasselhoff said she personally had not faced the same pressures as Nelson, but she was aware of other models feeling the need to "go to extreme lengths".
“But I heard of models who started at 14 years old with such small hips, and then at 16 agents said 'are you slacking off?' and they would say back, 'what, no, I’m just growing, I’m developing,' said Hasselhoff.
"Girls feel they have to go to extreme length to live their dream."
Hayley Hasselhoff said she was honoured to be speaking at the inquiry
Dunja Knezevic, a former catwalk model and founder of the modelling union at Equity, told MPs she had often seen extreme symptoms of eating disorders at fashion shows.
“I saw queues of girls at Milan fashion week with this fur all over their bodies, what the body produces to keep warm when there is no fat left. They were covered in it and I was just mesmerised by how hairy they were,” she said, according to The Guardian.
Knezevic also called for a crackdown on underage models, whom she described as, “cheap labour, 14-year-olds from Siberia who come over, are paid badly and end up even owing money to the agencies because when they grow, develop into women, they can’t fit the sizes”.
Karen Diamond, director of Models 1, spoke in defense of modelling agencies' current practices.
"There are certain measurements that are required to be a fashion model," she said, according to The Daily Mail.
"I don't think they are unreasonable or unachievable for somebody if they have the right body type."
Diamond also spoke about how she currently assesses the health of a model, and explained there are physical signs she looks out for that suggest a model may have an eating disorder.
"There's a pallor to the skin. There is a lack of vitality, something in the eyes," she said.
"If someone is making themselves sick then there may be bad breath, the teeth may show signs of having acid from the stomach. If someone is extremely underweight they usually have a downy look on their face, and excessive body hair."
Diamond's colleague James Horner, managing director of Models 1, said he had only seen two girls in the past 15 years who looked unwell and with whom he felt he needed to have a conversation about their health.
The MPs also heard from GP Dr Ellie Cannon who told the hearing teenagers had come to her practice to ask for a prescription for a certain type of contraceptive pill after being advised to do so by their agency.
"They have been told to do this so they don't gain weight," she said. "And it's often medically inappropriate."
Diamond said she would be open to an age restriction on catwalk models under 18, but cautioned against using BMI to measure health.
"Fashion models have a certain physique," she said. "Most fashion models are under 18 in BMI, that doesn’t make them unhealthy, but it is very difficult to police."
Nelson agrees that BMI is not the best way to measure models health.
"BMI is a very blunt tool which doesn't consider personal diets or exercise regimes when determining a person's health status," Nelson told HuffPost UK Style.
"I would rather see a different set of health checks put in place where models are asked to provide regular health certificates from their doctor.
"I believe the agencies representing models also have a responsibility of care for their girls. They should make time to regularly discuss health and well-being with their models, to ensure they are looked after in the workplace.
"If a law was brought in that required models to have health checks every three to six months then we would see a huge change in the modelling industry within the first year."
The all-party parliamentary group will now compile a dossier of the evidence they have heard and are expected to submit their recommendations in January.