I am not aware of any study (that has been made public, remember they always have that option at the end) by a pharmaceutical company or university that was set out to test whether water fasting for 5+ days is beneficial in treating or curing disease.
Several reasons:
1. They conducted one, but didn't like the results.
2. "Don't ask what you don't want to know the answer to" applies here - there is ZERO benefit in discovering that water fasting indeed reverses diseases to which these entities have vested interest in keeping their symptoms a lifelong struggle to patients. Nothing good would come out of it for them. The entire modern medical business model would collapse.
Tin foil hat? Sure, label me that. All I can do is drop tidbits that may be helpful to someone now or in the future. I already know that I've helped a couple dozen people personally in the last few years, myself included.
Those people would still be in a very bad shape if they waited for government or pharma company to endorse what has already been proven to be used successfully for hundreds of years as a primary healing treatment.