At 17 you are a young adult, and well I think fasting is entirely individual but yes in very rare circumstances would a child fast out of choice, more so they will abstain from food to recover from a flu etc. I’d say the most important thing is being open with family and preparing your body for this journey, it’s very healing.
As far as I know, people commonly recommend minors don’t fast because kids are still growing & developing. Both of which are highly demanding in terms of energy. Plus vitamin/mineral deficiencies in childhood can damage a person for life. Fasting can make it more tricky to make sure those things don’t happen. My understanding is that it’s one of those “better to error on the side of caution” type of things.
Though one of my classmates back in middle school did ramadan (a religious form of fasting) with her parents, and she seemed perfectly fine.
Some people like Dr Jason Fung define fasting any time you aren’t eating. So anyone who doesn’t eat in their sleep is technically fasting on a daily basis.
Also, being 17 means you’re very close to being an adult (18) anyway. It’s not like you’re 13 or 7 or something like that.
I’d have to know more about your situation to have a more solid opinion/advice. Why do you want to fast? What sort of fast do you mean? IF 18-6 is really different than 10 day extended. Do you do sports? How’s your mental health? What about physical health? What BMI range are you in?
If you decide to fast, definitely make sure you’re extra careful. It’s better to end the fast & try again another time than hurt yourself. Though that’s what I’d recommend to anyone really, regardless of age.