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 on your iPhone or Apple Watch. Export your data to a spreadsheet for complete control.

Zero supports the following fasting types:

16-Hour (16:8) 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.

We also support 18:6, 20:4, and 36-Hour fasts.

Custom Fasting: Set up a custom program to meet your fasting goals. You choose your fasting hours, up to 5 days long.

Zero is also available on Apple Watch.

Zero integrates with the Health app to sync your weight data.

What’s New

Version 3.0.2

Lots of awesome updates based on your feedback to the recently released Zero 3.0

• Faster loading times across the app
• New end of fast experience with fewer taps
• You now have one more way to delete a fast -- from the Journey screen, find the fast you want to delete, and long press on that fast. An option to delete the fast will appear
• Improved swipe navigation between your Stats and Journey screens
• You can update your account email address from the Settings screen
• Pull to refresh the Learn tab
• Privacy Policy now viewable on the Settings screen
• Even though we don't think you'll need this, you can now delete an account from the Settings screen
• Other fixes and enhancements

Ratings and Reviews

4.7 out of 5
8.1K Ratings
8.1K Ratings
1e99 ,


This “update” wrecked a perfectly good app by forcing facebook / email sign up. I’m appalled this was issued without warning long time users. I’m tired of entitled app developers and unnecessarily intrusive apps. *DELETED*.

JohnnyFor ,

Enjoyed the app until recent update

It now requires and account and signing up... for a timer app. Come on.

CrappyGamerMom1979 ,

Helpful for fasting and to know your fasting "windows"

Pretty well done and simple


Big Sky Health, Inc.
59.1 MB
Health & Fitness
Requires iOS 11.0 or later. Compatible with iPhone, iPad and iPod touch.
Age Rating
Rated 12+ for the following:
Infrequent/Mild Medical/Treatment Information
© 2019 Big Sky Health, Inc.


  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.

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