Extended Fast Planner
Set a length and see what your body does, and exactly when you finish.
This planner turns a fast length into a clear finish time and a map of what typically happens along the way — when stored sugar runs low, when the body switches to burning fat, and when deeper ketosis sets in. The milestone timings are educational ranges, not a prescription, and everyone responds differently.
How long is your fast?
60h
When do you start?
—
You finish
60h
Length
Deep ketosis — fat is the main fuel
State at the end
What your body does, and when
16h · Fat-burning switch
24h · Ketosis begins
48h · Deep ketosis
60h · FastNow target
Educational estimate only. Extended fasting is not for everyone — talk to a healthcare professional first, especially if you are pregnant, underweight, take medication, or have a health condition.