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Zero is a simple fasting tracker used for intermittent, circadian rhythm, and custom fasting. Choose your favorite fasting protocol and Zero will track your ongoing progress. Export your data to a spreadsheet for complete control.

Zero supports the following fasting types:

16-Hour Intermittent Fast: Popularized by Hugh Jackman and Dwayne “The Rock” Johnson as a fast to trim extra pounds. It is common to fast after dinner to around lunch the following day.

Circadian Rhythm Fasting: Based on the research from Dr. Panda (Salk Institute), participants are encourage to fast 13 hours per day, starting each fast at or before sunset. Zero uses your location to calculate the daily sunset time for the best possible accuracy.

Custom Fasting: Setup a custom program to meet your fasting goals. You choose your fasting hours per day, and days per week.

What's New

Version 2.2.0

- Start fast reminder: You can now set a daily "start fast" reminder.
- Toggle time display: Tap the time to switch between Elapsed Time and Remaining Time.
- Misc bug fixes.

Customer Reviews

4.8 out of 5

18.4K Ratings

18.4K Ratings

Great for Intermittent Fasting


I follow a keto diet and lifestyle and eat in an 8 hour window. Zero helps me track my 16 hour fasts. You can create a custom fast time period and then press Begin Fast when you’re done eating for the day. When you meet your goal, an alert pops up to let you know you have been successful. I am VERY grateful for this alert because I would probably forget to eat otherwise. My appetite has really diminished on keto, and since I’m a First Responder, I can’t risk rushing off to a emergency and suddenly realizing I’m famished and haven’t eaten in 20 hours (it’s happened and it SUCKZ). Zero helps me remember that I’ve given my body a rest from digestion and it’s time to refuel for the day’s adventures. I simply get my meal 🥓🥦🍳🥑☕️, press End Fast, and chow down. After dinner I just repeat the same steps.
So simple and so effective 👍🏼

Simple fasting app with clean interface


I’ve enjoyed using this app over the past three weeks, though I’ve been fasting intermittently alongside keto since August with my wife. The interface is simple and doesn’t get in the way of what I want to do. The export feature is easy to use.

The lastest update includes a disclaimer, which is a professional move by the publisher. Please read it carefully. Don’t attempt the 16-hour fasts without careful study and speaking with a health care professional. Much of the science behind fasting is positive, but certain conditions may complicate.

My one recommendation on improvement would be to add a widget for quick glances at fasting progress rather than being forced to jump in and out of the full app. Perhaps this could be a feature requiring payment.



I absolutely love the app, however I would like to recommend adding in the ability to make your custom fasts longer than 24 hours. Specifically for those people who love doing longer fasts, such as 36, 48 and 72 hours. I myself am a big advocate of longer fasting, however the moment I got my iPhone, I knew I wanted this app. The sunset counter is amazing and the app is beautiful. But again, I’d love to be able to track and be notified of fasts longer than 24 hours. Seeing the pop up say that my fast is up is the most satisfying feeling in the world. Thank you for such an amazing app and keep up the good work!


Courtney Circle LLC
48.6 MB
Health & Fitness
Requires iOS 10.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2017 Courtney Circle


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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