It is best to listen to your body and take the fast one day at a time.
I have heard of people fasting on water only for 90-days. Is that suicide? Possibly if not executed correctly. But usually people that push 20, 30, 40 and up are sane and understand the fundamentals.
Suicide is breaking a fast incorrectly. Imagine fasting for 30 days and then driving through a fast food joint. That is an excellent way in killing oneself.