Need help badly.

Hey basically I wanna do a 7 day or longer fast but when I am done I don’t know what to do I am scared I’ll gain all the weight back plus more what should I eat after the fast? It’s also worth mentioning I only have very limited food I have oranges,blackberries,pineapple,bananas,broccoli and salads with meat. More stuff to mention is that I fast until dinner time so I only eat 1 meal a day anything I want how do I bring back myself to eating like this after the fast. I am also really scared about my metabolism dropping so low I won’t be able to eat properly. Please help me if you know anything about fasting as I don’t know much at the end of fasts.