I managed to stay without any food for 7 days. Then all the muscles started to get cramps, your legs can't support your body anymore. So it will take a lot more than 7 days because your body will use the muscles before using your organs to get energy, than you die. From and old reddit post, a guy posted a real fact about a preacher that tried to follow the Jesus Fasting and died before achieving, so you can take it like 15 days perhaps