Fionnuala Kennedy, a deputy headteacher at Wimbledon High School, decided to send a message to the parents of the pupils at her school after watching the Netflix drama To The Bone.
In the message, she urged parents to be better role models for their children and avoid speaking about losing weight and cutting out foods in front of their teenage kids.
'Role model as effectively as you can. Its difficult to advocate a rounded, healthy diet for your teen if you've cut out carbs and dairy yourself, or frequently refer to your desire to lose weight', she wrote.
'We are all role models. Mothers, teachers, aunts — you will be looked up to even if you don’t realise it, and it is your job not to propagate the idea that thin is just better.'
Lily Collins stars in the film with Keanu Reeves
She also raised concerns around 'irresponsible' films, which she says contributes to glamorisation of anorexia.
'To The Bone, with its emphasis on anorexia as an act of rebellion, as 'sexy' even, only adds to the 'thin is cool/right/attractive' argument', she wrote in her message.
Fionnuala, who says she was horrified by the film, acknowledged that the idea that losing weight is positive is ingrained in our society, but stressed that it's important not to pass the message on to young girls.
'We are all a bit culpable; it's quite a middle-class thing talking about cutting out food groups and clean eating', she said speaking to the Evening Standard.
'As a teacher when you come back from holiday and speak to your colleagues, one of the first things middle-aged women will say to each other is, ‘You look fantastic — have you lost weight?’ It’s ingrained in us as women, so we have to be really careful because these messages are picked up all the time.'
To the Bone is a Netflix production featuring Lily Collins and tells the story of a 20-year-old anorexic girl who struggles to recover from the condition.
It's has received some criticism for its treatment of anorexia, including a warning from national eating disorder charity Beat, who said the film is likely to be 'highly distressing or triggering' for people who suffer from eating disorders.