Disney princesses such as Elsa from Frozen can damage young girls' body esteem, research suggests.
Fictional characters beloved by generations of cinema goers actually promote negative female stereotypes by indoctrinating little girls at an early age, the study claims.
Elsa in Frozen has an unrealistically thin waist like many Disney princesses over the years, including her sister Anna, Jasmine from Aladdin, Ariel from The Little Mermaid, Cinderella and Snow White.
While many parents dismiss the films and merchandise as harmless, scientists said such things reinforce unhelpful stereotypes. Those who were most obsessed with a Disney princess - wanting to dress and be like them - were more likely to have poor body esteem. Study author Sarah Coyne said it made girls want to be thin, and want to avoid the sciences or jobs that are less associated with women.
She said: "Disney princesses represent some of the first examples of exposure to the thin ideal.
"As women, we get it our whole lives, and it really does start at the Disney princess level, at age three and four.
"I think parents think the Disney princess culture is safe. That's the word I hear time and time again - it is 'safe'. But if we are fully jumping in here and really embracing it, parents should really consider the long term impact of the princess culture."
The study of 198 pre-school children, based on reports from parents and teachers, found 96 per cent of girls and 87 per cent of boys had viewed 'Disney princess' movies.
More than six in ten girls played with toy characters at least once a week yet just four per cent of the boys did the same. Dr Coyne, from Brigham Young University in the US, said this can become problematic if girls avoid important learning experiences not perceived as feminine or believe their opportunities in life are different as women.
She said: "We know girls who strongly adhere to female gender stereotypes feel like they can't do some things.
"They are not as confident that they can do well in maths and science.
"They don't like getting dirty, so they are less likely to try and experiment with things."
Conversely, the boys in the study who played with princess toys also had better body esteem and were more helpful to others, suggesting the princesses provide a counterbalance to the hyper-masculine superheroes traditionally presented to them. But girls with the worst body esteem played more with the Disney princesses over time, according to the study in the journal Child Development.
Dr Coyne said children don't have to completely disengage with princess culture and merchandising as it is everywhere. She added: "I would say have moderation in all things. Have your kids involved in all sorts of activities, and just have princesses be one of many, many things that they like to do and engage with.
"It is frustrating when the dentist sees my daughter and says, 'Look at the little princess!' because she's so much more than that.
"When we talk to little girls, we hear less of 'You're so smart, you worked so hard, your body can do great things' but that is the more important message we should be sending. What drives me crazy is when you get a princess who is not gender stereotyped, like Merida from Brave.
"And then Disney slims her down, sexualises her, takes away her bow and arrow, gives her make-up - feminises her."