I have to fast for 55 days. this is not an option.
starting weight 231
goal weight 175
Seems like your reason for fasting is just weight loss, and judging by your past results that hasn't been enough to motivate you. In other words, you really don't want to fast, but it is merely a means to an end.
My suggestion is to forget about Pizza, and start eating more fruits, and vegetables, and drink green smoothies. Do this for a couple of weeks.
Then shoot for fasts that are more reasonable to build your confidence.
Yes, I know it isn't what you wanted to hear. Sorry.
Others here have given good advice. You might want to look at
It is one of my very rare spiritual posts, but you can ignore that if you are concerned with the material side of things. The fact is though... "A common scenario is for someone to break the fast after a few days due to the pressures of life, and then binge on comfort food"
I suspect you will be doing that too, unless you change your lifestyle to prepare for the fast.
Oh and here's a success story for you - me.
Weights are in kilograms, multiply by 2.2 for pounds. Good luck, and if the first fast doesn't work out, don't give up, come back here and keep trying. Oh and you drink water only on a water fast.