Reach your health goals with the #1 fasting app.

Zero is a beautifully designed tracker used for intermittent, circadian rhythm, and custom extended fasting. As the largest app-based fasting community in the world, Zero makes it simple for you to harness the power of fasting to improve your health.

Zero’s advisory team includes some of the world’s leading doctors and researchers, including our Chief Medical Officer Dr. Peter Attia, who guides our fasting protocols and content creation.

Zero makes fasting simple:

• A beautiful, thoughtful design makes it simple to start fasting

• Earn badges to celebrate your fasting milestones and stay motivated

• Set a weight goal and track your progress

• Visualize your fasting progress over time

• Reflect on your fasting experience with the fasting journal

• Weekly articles created by our expert content team to keep you informed and motivated

• Stay accountable with group fasts and special events

Quickly start your fast based on science from leading doctors and researchers.

• 16 hour fast, known as the 16:8 Intermittent Fast, used by celebrities like Hugh Jackman and Halle Bailey when preparing for blockbuster films

• Circadian Rhythm Fast, based on research by Dr. Satchin Panda (Salk Institute), this 13 hour fast starts at or before sunset to align your eating window with your body’s clock. Zero automatically calculates the daily sunset time based on your location

• 18 hour fast, known as the 18:6 for more advanced fasters

• Other popular fasts include OMAD (one meal a day), 20:4 fast and custom fasting up to 7 days

Choose your favorite fasting protocol and Zero will track your progress on your iPhone or Apple Watch with Apple Health integration to sync your weight, resting heart rate and sleep.

Join the largest fasting community in the world!

What’s New

Version 3.6.1

Hi Zero crew,

It’s not spring yet, but we’re doing some cleanup here at Zero. Today’s release features a few fixes related to the new stats we recently launched.

Speaking of stats, we’re about to hit 1 billion hours fasted! Keep an eye on the ‘Who’s fasting?’ page in the app to see us hit this huge milestone together.

Thank you for your continued help finding bugs for us to squash.

Happy fasting,
Team Zero

Ratings and Reviews

4.8 out of 5
1.8K Ratings

1.8K Ratings

anweshanam ,

A handy tool

I am a 65 year old diabetic woman trying to manage my blood glucose with a low carb diet and intermittent Intermittent Fasting. Intermittent fasting is not observed by me at regular intervals, only when my blood glucose goes a bit out of control. And this App is a very useful tool to track my fasts.
I do not have to watch the clock .
This App also has different kinds of fasts and is flexible. There are also resources that helps us.
Good on the whole.

Tritinum ,


I like the additional functionality compared to the previous version but not on the cost of speed. All I see is loading in this app.

I would recommend stripping it a bit to make it as zippy as it was before.

vinaymahendru ,

Amazing way to track fasts

One of the easiest ways to track a fast and accurate timing . The editing should be made a little easier . It is hidden in too many layers . Also should be possible to edit a fast start time without ending fast .


Big Sky Health, Inc.
114.2 MB

Requires iOS 11.0 and watchOS 4.0 or later. Compatible with iPhone, iPad and iPod touch.



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  • Family Sharing

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

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