How much weight would I lose and is it safe?

i an 5’9-5’10 i weigh 240lbs i want to get down to 200lbs and then start building muscle up i am not unhealthy overweight i am a boxer and have good cardio and stamina and i workout to keep a good level of fitness but i want to lose my dad bod look for a lean build i am strong and fit bit i want to do it for the aesthetic look how long would i have to fast to lose 40lbs and would it be healthy i am currently doing a 20-4 intermediate fasting but i want a faster progress i plan to do a water fast for 10 days and then 10 days normal then 20 days fast what is the best way for me to do this

How much weight would I lose and is it safe?
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