Your survival depends upon food and water both, but here's how long you will survive without them or with any of them.
Your body adapts to the challenges within eight hours of fasting or not eating anything and starts converting glycogen into glucose from your liver.
The maximum number of days you can survive without food is 08 or 21. Depending on your body type, your starvation may end your life in between.
You can live up to two months or more if you are drinking an adequate amount of water daily, for our body is 60% water, answering how it is possible.
You wouldn't be able to walk as your blood pressure will fluctuate to heart attacks or paralysis. You will experience frequent faints and even fail an organ.
Feeding junk or stiff items after starving for days may cause heart failure. You'd need a doctor's supervision, who'd start with boiled vegetables.