Prophets are different and as our Prophet said, not to do what he did as he was fed by angels. Our Prophet fasted continually with no problem, but through medical research and documentation what he said has been proven.
Continual dry fasting is not healthy. Do it like I told you and you will be healthy. But there is more to fasting than just prayer, no water or food. I have dry fasted for 18 years and guarantee you I know of what I speak.