When to stop a fast

Stop now: warning signs

End the fast and get medical help if you feel seriously unwell, especially dizziness, confusion, chest pain, fainting, or severe weakness. Those are not ordinary hunger.

Also stop if the distress is more than ordinary discomfort: panic, inability to think clearly, or a sense that you might pass out. Do not drive or keep training through that.

If you take medicines that affect blood sugar or blood pressure, or you live with a condition such as diabetes, stop sooner and contact a clinician. This app cannot read your labs or your symptoms.

If you are already past 72 hours, read Signs on a very long stretch for more information.

Stop or shorten: illness, sleep, stress, training

A fever, stomach bug, migraine, or the start of an injury is a reason to eat and recover. Do not “use the fast to rest the gut” unless a clinician told you otherwise.

A wrecked night of sleep, a grief day, an exam, or a very hard training block can make the same hours feel unsafe or pointless. Shortening the window or taking the day off is a reasonable choice.

Hunger that comes in waves, then eases with water and a change of scene, is common early in a daily fast. Hunger plus warning signs is different. When you are unsure, stop. You can fast another day. You cannot undo fainting.

Planned endings vs “one more hour”

If you set a 16-hour target, ending at 16 hours is success. You do not need extra hours because a name such as fat-burning appeared on the timer. Those stage names are not a finish line. Read What the stages on the timer mean for more information.

If you are using Open (no finish time), decide a stop rule in advance: a clock time, a feeling check, or a maximum you already chose. Open is there so the clock can keep counting. It is a poor reason to bargain with yourself every hour past the time you meant to eat.

Social meals, travel, and family events are valid planned endings. Moving dinner earlier only to protect a streak is not a sustainable rhythm. Read Keeping a window in real life for more information.

After you stop

After a typical daily window, a normal balanced meal is usually enough. After a longer or multi-day fast, eat more gently, smaller portions first. Read Breaking a fast gently for more information.

Tap End Fast so history matches what you actually did. Ending early is still a finished fast. Do not hide the row, and do not start a longer fast next to make up for it.

The timer does not decide

MyFastingClock will not stop you for symptoms. Unlimited duration means the clock can match a long plan. It does not mean longer is wiser.

If you notice you never allow yourself to stop, or you only feel allowed to eat when a number looks “good enough,” step back and talk to a clinician, especially if food has been a difficult area before. See Who should be careful with fasting.