How Does the Blimbi Fasting Timer App Work?
Use Blimbi's fasting timer app to start and end a fast, correct times, save a partial fast and review your week in Progress. It never ends a fast for you.
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- Blimbi Editorial
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In 30 seconds
Blimbi’s fasting timer starts when you tell it when you last ate and stops when you tap End fast. You can finish early, correct the times and save the fast to your journal. Blimbi never starts or ends one automatically.
- Blimbi has only two states: Fasting and Eating.
- Start fast now asks when you last ate, so you can start from a real time up to seven days back.
- Ending early is never a failure: depending on progress, Blimbi offers to keep going, save a partial fast or discard it.
- Start and end times can be corrected later from the home screen, the summary or your journal.
- Phase names are a time-based educational guide; Blimbi does not measure your body.
What does the fasting timer show?
The Fast tab shows Fasting or Eating. During a fast, its phase name is an educational label based on recorded hours, not a reading from your body.
There is no single hour when the metabolic switch begins for everyone; timing depends on prior meals, activity and individual energy stores.Source 1
| State | What the screen shows |
|---|---|
| Fasting | A single ring that fills toward your target, the elapsed time, the time left, and the START and PLANNED END cards |
| Eating | The time since your last fast ended and a suggested eating-window reference; it never starts the next fast for you |
Reaching your target does not end the fast. The ring shows extra time, and you decide when to finish; longer is not a goal in itself.
How do you start a fast?
On the Eating screen, tap Start fast now and answer When did you last eat? Choose Now, 1 h ago, Last night or Other time. The picker reaches seven days back and asks for confirmation if the start was more than 48 hours ago. Then choose a target for this fast; it can differ from your usual protocol. Confirm with Start fast or Start from and the chosen time.
To work out when each protocol ends, see how to calculate intermittent fasting hours. Blimbi is available on iPhone and Android; download links are on the Blimbi app page.
How do you end a fast early?
Tap End fast. If you passed your target, the summary opens. If you finish sooner, the options depend on how far you got.
| Progress | Options |
|---|---|
| Less than 25% | Keep fasting, Discard fast (nothing is saved) or Move start |
| 25% to 75% | Keep fasting or Save as partial |
| More than 75% | Continue to target or Finish now |
The summary shows your duration and editable start and end times. Tap Save to add the fast to Journal; a partial fast still counts in your week.
Can you correct a fasting time?
Forgot to start on time? Correct the start during the fast, edit either time in the summary or change a saved fast in Journal. Blimbi rejects future times, an end before the start, fasts longer than seven days and overlapping records.
| When | Where | What you can change |
|---|---|---|
| During a fast | Edit start on the START card, or Correct start time under Restart or other options | The start time |
| During a fast | Change today's target | Only the current fast; on iPhone it opens Adjust this fast, where you can move the start or the planned end |
| After ending | The summary | The start and end times |
| Later | Journal, with Edit fast | The start and end times |
Where can you see your progress?
Each saved fast appears in Journal with its start, end and target, marked as met or partial. Journal shows your total, average, number of fasts, monthly calendar and recent records; Record fast adds one you missed. YOUR WEEK and Progress show weekly hours and four-week averages. There are no streaks: milestones mark consistent records and your chosen targets, not longer fasts.
Are Blimbi’s phase names exact?
Mixed evidence
Why phases are labelled as estimates
The phases are estimates. Reviews describe a gradual shift from glucose toward fat and ketone use, but its timing varies with prior meals, activity and energy stores. Blimbi counts recorded hours; it does not measure these changes.Source 1
When should you end a fast?
At 36 hours, the ring turns blue and Blimbi shows a safety notice and asks Are you still there? Extended fasts need professional supervision; end the fast if you feel dizzy, severely weak or confused. Blimbi is a timer and journal, not medical care.
Talk to a qualified health professional before fasting if you are pregnant or breastfeeding, under 18, living with or recovering from an eating disorder, have diabetes, take insulin or a medicine affected by meal timing, are an older adult, or are acutely ill. Do not change the dose or timing of any medicine without your clinician. See Blimbi’s safety guide.
Frequently asked questions
Can a fasting timer app tell when I am in ketosis?
No. Blimbi only counts time. Its phase names are an educational guide, and reviews do not support one hour when the metabolic switch begins for everyone.Source 1
Should I keep fasting after reaching my target?
You can finish whenever you want; going longer is not a competition. From 36 hours Blimbi shows a supervision notice because extended fasts need professional oversight, and people with diabetes face risks such as low blood sugar and dehydration that need a clinician's plan.Source 2
Sources
Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of FastingStephen D. Anton et al. Wiley, February 1, 2018.DOI: 10.1002/oby.22065 · PMID: 29086496Narrative or mechanistic review
Fasting Safely with DiabetesMartin M. Grajower. National Institute of Diabetes and Digestive and Kidney Diseases, August 26, 2020.Official guidance