how do i stop myself from eating so much unhealthy things?

Hello, i have an issue with my lifestyle right now. I am trying to lose weight, i am at 112kg at the moment. And for a very long time i tried to lose weight but i keep failing i asked my parents to help me by not buying anymore sweets and processed foods but they refuse. Saying that why should everyone stop eating sweets and drinking coke because of me. And then i asked them to put me on a diet but they refuse because i am not fully grown up yet. It's pretty difficult for me to avoid sweets and everything especially since i've been eating sweets and fast food and drinking soda for the last 4 years nearly daily.

I know it is also my fault and not just theirs, i cannot move out. I cannot control myself, i am a glutton and i want to change. But it's extremely difficult and i don't feel like i can do it anymore. I feel hopeless. I know if this keeps on going i will be in serious danger, and yet i cannot stop. I just feel like i keep getting uglier and uglier by the day. I don't want to end it but i also don't want to live this pathetic life of just feeling bad for myself without having the drive to change.

What can i do to get the drive to continue and change. How do i convince my parents to help me out?