Closing gyms during lockdown led to rise in people feeling insecure about their bodies, MPs have warned.
Two-thirds of under-18s and 61 per cent of adults feel negative or very negative about their body image most of the time, according to an online poll by the Women and Equalities Committee (WEC).
The survey, which received 7,878 responses, invited people to share their responses via social media between July 6 and 19.
It found that the majority of people feel negatively about their body image most of the time and lockdown has exacerbated these feelings.
The survey found that over half (53 per cent) of adults and 58 per cent of under-18s said the coronavirus lockdown made them feel worse or much worse about their appearance.
Women said they felt anxious about gaining weight during lockdown and were bombarded with online adverts to improve their appearances as they spent more time inside consuming social media.
Furthermore, the closure of gyms, less support for eating disorders and widespread discussions in the media of lockdown weight gain added to the pressure they felt.
One young woman wrote: "I feel women constantly have diet and exercise adverts thrown at us on social media and TV and it's very overwhelming, particularly during this lockdown I've noticed it more.
"It makes you feel like you HAVE to be on some sort of diet."
Another respondent said: "As a clinical psychologist working with children and young people the impact... is apparent younger and younger. They are less able to ignore the 'ideals' pushed via social media.
"In addition, as someone who has recently become pregnant ... social media is already flooding me with 'bouncing back' to 'pre-baby body' advertisements. Very very unhelpful."
However others said the lockdown had given them a break from having to scrutinise their appearance each morning.
The findings suggest the majority of people do not feel reflected in the images they see, with people who are transgender, disabled and from black, Asian and minority ethnic (BAME) backgrounds least likely to feel represented.
Some 57 per cent of adults reported 'rarely' or 'never' seeing themselves or people who look like them regularly reflected in images in media and advertising.
Not a single transgender respondent felt 'very positive' about their body image, according to the poll.
Almost twice as many (23 per cent) reported feeling 'very negative' most of the time about their appearance compared with 12 per cent of cisgender participants.
One transgender woman said: "I have gone from hating my body due to dysphoria to hating my body due to pressures on women to conform."
Men also said they felt pressure to conform to stereotypes such as being tall and muscular, and were frequently targeted by adverts encouraging them to bulk up.
The Women and Equalities Committee held a session on Wednesday as part of its body image inquiry.
WEC chairwoman Caroline Nokes said: "Because it's such a widespread problem, influenced by multiple factors, it's easy to underestimate the real misery it causes - and to so many people. There has been plenty of commentary on the problem, but identifying proposals to tackle it is more challenging.
"Our inquiry aims to do exactly that: we will be hearing from a wide range of witnesses - both experts and individuals speaking from their own experience, and we will be making recommendations to Government early next year."