The complete guide
If it has calories, it breaks your fast. For maximum autophagy benefits, stick to zero-calorie items. The "gray area" items are compromises — they reduce benefits but may help you complete the fast.
The main reason to do a 72-hour fast is autophagy — your body's cellular cleanup process. Anything that triggers an insulin response or provides calories will reduce or stop autophagy. For maximum benefits, be strict with the "safe" list.