Anxiety and eating disorders can be two separate things but in most cases there is an existing correlation between the two.
Anxiety is mostly related to worry or stress and anxiety about eating or weight or your overall appearance can be caused due to current stress through social media. Social media is one of the biggest contributing factors of making one insecure about their appearance. Scrolling through your phone and finding multiple strangers online or celebrities who have the "ideal" and "perfect" body may make somebody feel insecure about how they look. Insecurity can come through comparison as well. If you grew up with family or relatives who always compared you to other people, you may necessarily be insecure around them as well.
This overall supports the fact that above provided factors and/or others are destroying young kids' mindsets. Insecurity and anxiety leads to eating disorders which can involve binge eating disorder such as eating an excessive amount or starving yourself such as not eating a sufficient amount. These are of-course a few examples only, there are multiple variations of the disorder.
In the end, no one should feel the need to change themselves based on other people or their opinions.