What the stages on the timer mean

Why the timer shows names

Many people want a sense of where they are during a fast. The names give language for digestion, shifting fuel, and longer stretches, without blood tests or a clinic.

The timer still measures one reliable thing: elapsed time. The names follow those hours. They are not a second measurement.

The names, in order (approximate hours)

These ranges match the timeline on this timer. People vary a lot. Sleep, the last meal, activity, medicines, and health all change how a given hour feels.

Fed State (about 0–4 hours): you are still digesting the last meal. Textbooks treat glucose from that meal as the main fuel story.

Early Fasting (about 4–8 hours): insulin often falls after a meal, and the body starts using more stored fuel. Hunger in waves is common here. Read Hunger comes in waves for more information.

Fat Burning (about 8–12 hours): textbooks often describe more use of stored fat as glycogen (stored carbohydrate) runs lower. How you feel still changes day to day.

Ketosis (about 12–18 hours) and Deep Ketosis (about 18–24 hours): ketone production often rises when carbohydrate is lower. Feeling clear or feeling foggy can both happen. Neither proves a blood ketone number.

Autophagy Window (about 24–48 hours): “autophagy” is cellular cleanup. Online threads treat hour 24 as a switch. Biology is slower and messier than that. The name is a bookmark for a longer fast, not proof that cleanup started on the hour. Read Autophagy: what headlines get wrong for more information.

Deep Fasting (about 48–72 hours) and Prolonged Fast (72 hours and up): longer territory. Risk and discomfort can rise. For a stretch past a day, talk to a clinician who knows you. Unlimited tracking lets the clock keep counting. It is not a dare to stay there.

What the names are not

The app cannot measure insulin, ketones, glycogen, or autophagy in you. Seeing Ketosis on the timer is not a prize and does not mean you must continue. A later name only means more hours have passed. Two people at 12 hours can feel completely different.

How to use the names

Use them as quiet context while you follow a plan you already chose, such as a daily window. Pair the name with how you feel and with water, not with a streak you have to protect.

Short tips for each name are on Learn. If you feel dizzy, confused, faint, severely weak, or panicky, tap End Fast and get help. See When to stop a fast. No name is worth pushing through those signs.