Why?

Because I didn't know the context of your post, I went to read the others you've written on here so far. I hope it wasn't too invasive. If it was, please message me so I can apologize to you properly.

I'm not sure if you get the chance to read the comments you get because it seems like you have a difficult family situation and restricted access to internet, but it's a bad idea to do a water fast in order to lose weight. When your body doesn't get enough nutrients, it starts to hold onto everything it can. You can start to swell as well from lack of protein. When you're growing as a teen your body will go through a lot of changes in weight as it adjusts into your adult frame.

I understand that for a nonbinary teen weight changes and growth can lead to dysphoria, but please know that there are healthier ways to combat that instead of going for a water fast in order to prevent physical changes. There are tips online for foods that promote hormone production, which can change some of how you present. Wearing certain types of clothing can disguise your figure. Appropriate amounts of exercising, though tedious, can build muscles and change your frame, though it's also important not to overdo it. If you are 14, you can do part-time work with the permission of your parents and save up for resources and emergency money. Once you turn 18, you are able to take legal control of your life and make the changes to it that you want.

If you do a water fast improperly, you will end up the hospital and it may lead to further supervision. Online guides for any sort of fasting are not reliable. I don't want you to feel cornered because there are always better options, even if it is difficult to find them sometimes.