When each stage begins, on your own clock.
Choose a plan and when you last ate. The planner lists the body stages the plan passes through and the time each one begins where you are, then the planned end and, for a fast of a day or more, the refeed days after it. It is worked out in this browser; nothing you enter leaves it.
Not for under-18s, pregnancy or breastfeeding, a history of eating disorders, or anyone advised against fasting. This describes what research measured in healthy adults, not your body.
The planner works out its times in your browser and needs JavaScript switched on. Every stage, with its evidence and papers, is on Stages.
Supervised · only with a clinician. Plans over 72 hours are for fasting under a clinician’s care. Before each one the app asks for three things: a clinician is supervising this fast, electrolytes are being monitored, and a graded refeed of at least three days is planned. Nothing runs past 120 hours. The safety rails.
Stop signs
End the fast and seek help if you feel faint or dizzy on standing, notice palpitations, confusion, a severe headache, cramps or weakness, or keep being sick. Not feeling right?
Refeed days
What studies measured in healthy adults, not a reading of your own body; timing varies from person to person. Each stage’s evidence and papers are on Stages.
Nesteia is in testing on iPhone and not yet on the App Store.
Free: every daily window, and plans and stages to 36 h. Pro from £4.99 a month at launch.