WARNING:Contains language and descriptions which may be triggering for self-harm and anorexia sufferers.
The programme, My Self-Harm Nightmare, was aired on Wednesday evening at 11pm, prompting viewers to criticise the late night slot.
Ofcom confirmed to HuffPost UK it had received four complaints about the show, and is currently assessing whether it will be launching an investigation.
An image of the graphic and shockingly-deep self-harm injuries of one of the participants, 18-year-old Becky, was broadcast. Becky recounts how, after cutting herself particularly badly, she was rushed to hospital and had to have her veins stitched up. The doctors operated on the teenager without anaesthetic - she was losing so much blood there was no time to administer it.
"I have been exposed to a lot of damaging material on the internet and this led to the development of my eating disorder," Becky told documentary makers.
Also included were images of 20-year-old Chrissy's self-harm injuries, and specific tips given by a third participant, teenager Charlotte, on how to cover up the marks.
The show included advice from websites on how to fast, and "devious" tricks from Charlotte, who used to use to con her parents into thinking she had already eaten, as well as pointers on how to induce vomiting.
Channel 4 also showed what former sufferer Chrissy used to look like at the height of her illness, including topless pictures of her frail, skeletal frame.
The programme repeatedly used images of half-naked anorexic females, some covered in bruises, as Becky and Charlotte detailed their drive to become thin.
"You compete to be the thinnest," explained Charlotte with a smile. "Being the thinnest means you're the strongest."
When Charlotte recounts the vast amount of laxatives she used to ingest, a shot of a laxative product on a well-known website is shown on screen.
Last year alone, 38,000 teenagers were admitted to hospital with self-harm injuries, while more than one million people with an eating disorder have used pro-anorexia/bulimia websites.
In an old clip of a video which she posted on her blog, Chrissy cries as she says: "People say I'm beautiful, but they can't see me with sick in my hair, sick all over me, lying on the floor unable to get up.
"This is not a choice. I don't want this. Why would anyone want this?"
Speaking in further detail to HuffPost UK via Twitter, Louise added: "It wasn't addressed with any sensitivity or awareness of it's obviously vulnerable audience. No mentions of treatment just shock.
"No need to use such graphic imagery or give the audience a complete guide to self-harm. Would love a programme focused on a broader range of self-harmers that delves deeper into understanding and treatment options without being graphic and triggering."
The programme showed graphic close-up images of self-harm from the start, including one of a girl's arm covered in blood as a result of her cutting herself during the opening minutes.
Alison Kerry, head of media at Mind, told HuffPost UK the charity was "disappointed" in Channel 4.
We know that the use of graphic imagery about self-harm and anorexia can be potentially very harmful, encouraging behaviour and reinforcing ideas.. Studies have shown that some media reporting can lead to copycat behaviour.
"We encourage the media to report on mental health problems and to make sure they are giving people with lived experience the opportunity to speak out. However, it has a responsibility to do this sensitively."
Viewers, including those who had experience of anorexia and self-harm, took to Twitter to express their disgust with Channel 4.
Discussions of the documentary have also appeared on a pro-anorexia site, with users saying they found it "triggering and sensational" and "full of dramatic shots" - without focusing on actual mental health illnesses.
Becky has been home from hospital for a year now, and says her aim is to stay out, while Charlotte says she thinks she is strong enough to fight her issues. "I hope I am. I don't want to go back to hospital," she says. Charlotte is currently attending college and studies performing arts, and goes to theatre school at the weekend.
"There's so much other stuff going on that you enjoy so much it [her problems] just doesn't exist anymore there."
Chrissy, meanwhile, has sought help and "threw" herself into recovery. "I needed to reach out and become part of the world again." She achieved an A* and two As in her A-levels and will be attending York University.
"I'm looking forward to moving on."
A spokesperson for Channel 4 told HuffPost UK: "The programme makers felt that it was important to bring the nature of the material readily available to wider public attention so that responsible adults can recognise the signs that a young person may be self-harming and/or are viewing these sites.
"Any images shown were carefully considered and presented in the context of the damage they cause. The production company consulted with a psychologist throughout the making of this film."
Useful websites and helplines:
- Samaritans, open 24 hours a day, on 08457 90 90 90
- Mind, open Monday to Friday, 9am-6pm on 0300 123 3393
- Young Minds offers information to young people about mental health and emotional wellbeing
- Students Against Depression, a website by students, for students.
- HopeLine runs a confidential advice helpline if you are a young person at risk of suicide or are worried about a young person at risk of suicide. Mon-Fri 10-5pmand 7pm-10pm. Weekends 2pm-5pm on 0800 068 41 41
- HeadMeds - a straight-talking website on mental health medication
- Student Minds supports students across the UK to bring about positive change on their campuses through campaigning and facilitating peer support programmes. To join the community or launch a student group contact the charity on email@example.com