I am no expert but I think it will be hard to maintain a fast for a period a time to lose 100 lbs. My suggestion is to try EOD fasting - every other day fasting - eating healthy on the the day you are not fasting. This is more doable for a long term goal. I too am struggling with weight and using Water Fasting to lose my last 30 lbs. by the end of the year. I lost 130 through healthy eating and exercise this past year. Fasting is definetly not a long term solution weight loss instead you must follow a healthy lifestyle.
Jump start with a five day fast and then start EOD fasting. You could also do a short fast once a month to keep yourself focused on the process.
The problem with fasting for such a big weight loss is that you will gain back 5 to 7 lbs after each fast when you eat. This becomes very discouraging when you have a large amount to lose. You will be on a high losing 10 lbs in five days and then when you eat it quickly comes back on. I don't know maybe you will feel differently. If you are disciplined enough to fast you should have no problems eating raw or at least a majority of fruits and vegetables. If you do this I can pretty much guarantee the weight will fall off of you. Fasting is very emotional and overwhelming at times and I do not want you to be discouraged too easily.
I wish you the best of luck and I am pulling for you - if you want any info on the diet I followed called McDougall let me know or do a google search. I lost 65 lbs in three months on it - the weight loss slowed somewhat but I still was able to lose about 100 lbs in 8 months on it.
Happiness and Health