Methodology
The timer measures elapsed time. Its five reference markers organize educational text; they are not validated physiological boundaries for an individual.
How the timer works
The timer records when you start your fast (stored in your browser's local storage) and counts elapsed time. When you set a protocol — for example, 16:8 — the timer shows how much of your fasting window has passed and how much remains. No data is sent to a server.
Why these hour markers appear
The 0, 4, 12, 16 and 24-hour values are interface reference points. Published reviews describe variable changes in fuel use, not this exact five-stage timetable. Earlier meals, activity and individual biology affect timing. The markers do not establish when insulin falls, ketones rise or autophagy changes.
| Phase | Interface marker | Basis and limitation |
|---|---|---|
| Fed | Hour 0 | Zero is the recorded start after your last intake, not a measured end of digestion. |
| Early fasting | ~Hour 4 | Four hours is an illustrative early interval. It is not a measured glycogen-depletion threshold. |
| Fuel-use context | ~Hour 12 | Twelve hours is a reference for discussion of fuel use. Fat oxidation is not an on/off event at this hour. |
| Ketone context | ~Hour 16 | Sixteen hours is also a common schedule duration. It does not establish the onset of ketosis. |
| Longer fasting | ~Hour 24 | Twenty-four hours marks a longer interval on this display, not a verified state of deep ketosis or a recommendation to continue. |
Limitations and assumptions
The timer has no glucose, insulin or ketone data. It cannot measure autophagy or tell whether fasting is suitable. Do not use a phase label to make medical decisions, extend a fast despite symptoms, or change prescribed care.
Sources
- Cleveland Clinic — What Is Intermittent Fasting? (opens in a new tab)
What this source supports: Describes daily time-restricted eating and the weekly 5:2 pattern. The example clock times on this page are arithmetic illustrations. The source describes 16:8 and 14:10 directly.
What it cannot establish: Does not demonstrate that a longer fasting window is better or establish individual suitability.
Source checked:
- Cleveland Clinic — 6 Tips for Fasting Safely (opens in a new tab)
What this source supports: Discusses planning, hydration, medication and avoiding extreme fasting.
What it cannot establish: General clinical education, not approval of this exact schedule for the reader.
Source checked: