At the start of the year I had no idea what body image was. But over the past few weeks I learnt a lot about body image.
So body image is how people see you visually. For e.g if someone sees you in the streets and you may have a disability like you have a short leg they may judge you. But if you have a positive body image you wouldn't care what anyone says or thinks about you therefore you are happy and have a strong relationship with your body.
But if you have a negative body image you may harm yourself in multiple ways. If you are a little bigger than others and they bully you for being overweight. you might just starve yourself, or force yourself to go to the gym everyday even though you don't want to. A lot of people do these things just so they don't get judged by people.
People of all ages do this, it mostly happens at the age of thirteen. Personally i don't really care what others think therefore i have a positive body image and if you don't have a positive body image i suggest you do mostly so you don't waste your life caring about others opinion because the only opinion that should matter to you is your own ones. Don't care what others think and do what you want with your body.