From hour 18
Autophagy signalling
Signals for cellular recycling step up as fasting continues.
- Typical onset
- 18 h+
- Varies most with
- Largely unknown
- Measurable at home
- Not outside a lab
What’s understood
In cell and animal studies, prolonged fasting increases the signalling for autophagy — the recycling of worn cell components. Human data under everyday fasting conditions is limited.
What people commonly report
Little that is specific to this phase. Ongoing hunger, lighter sleep and feeling cold are commonly described on longer fasts.
What it isn’t
Not something a phone can verify. We won't say your fast triggered autophagy — nothing in an app can know that, which is why the phase is named for the signalling, not the result.
Where the evidence is thin
The evidence is largely mechanistic — from cells and animals, not from people fasting overnight. Hour 18 marks where studies commonly look, not where anything begins.
Sources
- Fasting: molecular mechanisms and clinical applications Longo VD, Mattson MP · Cell Metab · 2014 · Review
- Autophagy in human health and disease Choi AM, Ryter SW, Levine B · N Engl J Med · 2013 · Mechanistic