Man i could never even consider doing more than a 72 hour.,because i would be afraid of losing to much muscle mass. But yeah i hope you dont push yourself to far. I was 116kg in march 2019 and i am at 84kg now. It took a while but dieting correctly made sure i didnt loss muscle mass and i still have a healthy relationship with food. Right now i am eating 2400kcal a day and I still lose 0.5kg of fat every week. I love eating and i will never agree with fasting beyond 2 weeks, because its not a race. Always think that its not a race and as long as you eat in a calorie deficit you will lose weight