Body dissatisfaction can start as young as six and lead to depression, anxiety and eating issues, MPs will be told.
The Youth Select Committee urged the government to recognise the seriousness of body image fears, before young people suffered a long-term impact.
It is launching its report into the issue, A Body Confident Future, as part of the annual Parliament Week.
One expert said it was now normal for young people "to be unhappy with the way their bodies look".
Dr Phillippa Diedrichs, associate professor at the Centre for Appearance Research, University of the West of England, added that body dissatisfaction was the biggest known risk factor for eating disorders such as bulimia.
"It is a really important mental health issue, and I don't think it is taken seriously enough," she said.
There are also concerns that most campaigns are targeted at women, overlooking other groups such as young men, LGBT (gay, lesbian, bisexual, transgender) youth, ethnic minorities, and those with disabilities or serious illnesses.
The Youth Select Committee is a British Youth Council initiative, supported by the House of Commons, with 11 members aged from 13 to 18.
It decided to tackle the issue of body image after thousands of young people highlighted it as a concern, during the UK Youth Parliament's Make Your Mark ballot.
In July, the committee heard from expert witnesses, including bloggers, social-media companies, teachers and mental-health professionals, on the subject.
Its report, which will now be sent to the government for an official response, asks Parliament to:
- Address current knowledge gaps, especially about body image in pre-adolescents
- Develop resources for groups other than women, who are targeted in most current campaigns
- Introduce an annual National Body Confidence week
- Appoint a Government Equalities Office minister
- Hold workshops with the Be Real campaign and major brands to increase uptake of its Body Image Pledge
The report says: "Body dissatisfaction must be recognised as a serious issue which potentially affects every young person. This report is only the first step; far more needs to be done by society at large to tackle this issue."
'You get told your body is not the right way'
Seventeen-year-old Josh Dohetty suffered with body image issues in his early secondary school life but has now overcome his concerns.
He told the BBC: "Right now, it's died down and I'm a lot happier with my body than in the past.
"I was bullied in my first and second years at secondary school, but now I've just come to terms with my body.
"You get told that your body is not the right way and that you should look a certain way.
"It's issues like how your hair looks and are you masculine enough - stupid things like that.
"Most young people do have body issues, and it's because society is so concentrated on having the perfect look to get a boyfriend or girlfriend.
"Society should be more that it's OK to be any way, although not in a way that is unhealthy, and that being a bit bigger is not a bad thing and it's fine not to have perfectly coiffed hair.
"I would say to younger people if you are happy with how you look, then that's fine."
The rising use of social media is also blamed for causing young people to worry about their body image.
Kirstie Stage, a young person giving evidence to the committee, mentioned the "constant pressure to look good for regular Snapchats".
And another young person said: "If you get a lot of likes on a picture sometimes people can feel really happy with themselves, but if you don't get a huge amount people can often feel down about themselves, which is a huge part of social media."
However, there are positives for body image across the different social media platforms.
Fashion blogger Bethany Rutter said: "I see social media and my place in it as a way to plug the gap that is not being met by mainstream media."
She added: "It is a way to represent yourself and see people like you being represented."
Body positivity campaigns also have a high profile on social media, which allows people to connect with others offering support.
The report found that body image worries could affect very young children.
Susie Williams, a member of the NHS Youth Forum, said: "I know six-year-olds who don't go to school because the kids say they have hairy legs and they think they're fat."
Another study found that 10% of secondary school age boys had skipped meals and another 10% would consider taking steroids to achieve a particular appearance.
However, some campaigns have been set up to help people with concerns.