I used to be, back when I was around 8, and it lasted until I reached high school, so, when I was around 15-16. During my childhood, my mother and I moved away from my family because the apartment was too small for five people. However, since we were poor, we had to move far away in a shit-hole because the rent was cheap. Immediately, at my new school, I was ostracized by the other kids. I was considered ugly, and because we were poor, my clothes were shitty. And since I had moved out in the middle of the year, I didn't get to know them from the beginning and nobody wanted to get to know me, either. I'd always stay alone. It just hit me so hard, to feel like something is wrong with me because nobody would approach me. I'd ask myself, why would they dodge me like I had the plague? Until I heard someone calling me ugly behind my back - that's when I understood. Everybody sent me weird looks. Because of my loneliness, I stayed in my room and ate, ate, ate - food was the only thing that made me feel better, even though I felt awful afterwards. Soon enough, I became overweight. My mother was dealing with depression at the time, so she didn't really do something about it, and I don't blame her.
It just became so worst after that. Kids would still ignore me - but even though kids would not approach me, I still heard about what they'd said about me. Boys would joke that I looked pregnant, or would say things like "You'll have to kiss her" (talking about me) and they'd say "That pig? No way!" and either make disgusted faces or laugh. They would also laugh at me when we had P.E. because I had trouble due to my weight. I'd pretend I did not hear, but it killed me inside; and I'd go home and eat to feel better, making it worse. During middle school, I had developed somewhat of an awful attitude due to my depression, so I used snap at everyone that tried to bully me - but again, they always mentioned my body. It just became impossible to ignore the fact that I was overweight.
Here is a funny situation that happened when I was 9: it was picture day and my mother had done my hair, it was kinda cute. Lunch time arrives - my school actually had this weird rule where the lunch ladies would tell us where to sit rather than allowing us to be with friends, so I ended up at a table with a guy that I did not really know, I just knew his name. He took a good look at me and said, with an honest smile, "You look really good today," and judging by his tone, it was truthful. I smiled at him and thanked him, but then he continued by saying, "Yeah, you know, back when you moved in, we all told each other, "The new kid's ugly and fat," but right now, you look cute." and he genuinely thought he was being nice here. I lost my smile so quick, but I still thanked him again. Looking back at it, it was rather funny, but definitely not something a nine year old kid should hear.
Currently, I am not being body-shamed anymore. Thankfully, we adults are more mature about it lol, and to be honest I'm not the fattest in my class anymore. But I've been body-shamed half of my life and it's one of the two reasons as to why my self-confidence is so, so low. Bullying really can have devastating effects all the way to adulthood - no matter how many years pass, I'm still struggling with it because I grew up being aware of the fact that everybody thought I was hideous and fat. No matter how much I physically change, it's still a part of me that prevents me from truly appreciating myself.
To answer your other question, no, I did not consider CTBing because of it, and I wouldn't do it for that, either, because I have other reasons as to why I want to CTB. I'm not self-conscious about my body anymore - even though it's rather frustrating that some outfits don't look good on me - but being body-shamed definitely did impact me and my whole life. To be honest, I can't tell you how I overcame it because I don't really know myself, I guess I got other issues to worry about, like my studies and my depression which took over me. I didn't truly overcome it, but it has gotten easier to accept once people stop reminding you of how awful you are. If you have a good entourage, it should be a bit easier to overcome it.
I hope that one day, you will all be able to overcome it. Life is just so much more than appearance, you know? Even though society treats us like shit. It's something much easier said than done, because even though most days I'm okay with my body, there are some days when I just want to starve to death because of my weight - but sometimes you have to remember that there's more to life than that.
I'm sorry if that was too long to read. Body-shaming was something omnipresent in my life and rather traumatic, so I had a lot to say. If you don't feel like reading allat, you should probably skip to the 4th paragraph. Take care!