Zero: Fasting & Health Tracker 17+

Weight Loss & Metabolic Health

Zero Longevity Science, Inc.

    • Free
    • Offers In-App Purchases


Stop counting calories and start intermittent fasting with Zero, the world’s most popular fasting tracker and metabolic health app.

Zero maximizes your body’s natural fat-burning ability between your last meal today and your first meal tomorrow. Based on the science of intermittent fasting, we help you extend your natural overnight fast to increase fat burning and accelerate weight loss. By building simple, science-backed habits, you’ll lose weight, preserve muscle, and live better, longer. Best of all, you’ll do this without counting calories, tracking macros, or restricting foods.


Zero Members have lost millions of pounds — and that’s no accident. Featured in GQ, Good Housekeeping, Men’s Health, Fortune, Techcrunch, Women’s Health, The Tim Ferriss Show, The Joe Rogan Experience, and more, Zero is the world’s most popular intermittent fasting app for all skill levels, from those embarking on their first health journey to expert health and fitness coaches.


Zero is a science-backed, evidence-based approach to losing weight and burning fat effectively. In just 28 days, you'll start to see transformative results, beginning with weight loss and extending to better mood and improved energy, all while transforming your relationship with food. By the 3-month mark, you'll have improved your body composition along with metabolic health markers including waist circumference, fat mass, blood pressure, glucose, and insulin. And the best part? You’ll never need another diet again.


The world's most popular intermittent-fasting Timer helps you track your fasts, your progress, and your goals. Start your Timer and stay on target with all the popular intermittent-fasting types, including:

• 13-HOUR FAST, or “circadian- rhythm fast,” based on research by Dr. Satchin Panda (Salk Institute) that aligns your eating window with your body’s internal clock

• 16-HOUR FAST, or the 16:8 intermittent fast, used by celebrities, athletes, and millions of Zero Members to manage weight and improve metabolic wellbeing

• 18-HOUR FAST, or 18:6, for more advanced fasters

• Other popular fasts such as OMAD (one meal a day), the 20:4 fast, and custom prolonged fasts of up to 7 days


Zero has helped millions of Members form new habits and achieve their weight-loss and health-gain goals. In just a few weeks, you’ll shift your metabolism towards burning more fat with real-time tips, personalized stats, and our exclusive Fat-Burning Mode. Discover insights into the changes your body is experiencing, get daily guidance, and break through plateaus with this one-of-a-kind approach powered by the science of intermittent fasting.


Learn the science behind the daily habits that help you succeed on your journey towards weight loss and health gain. Every week, the Zero science team distills cutting-edge health research down to actionable steps and delivers the latest insights on everything you need to know to get and stay healthy. You’re never alone with Zero as your guide.


Stay focused with expert-led, science-backed content, community Challenges, achievements, and more. Zero is your partner for building healthy habits that propel you towards better, lasting health.


Streaks and Badges celebrate your daily progress throughout your health journey, helping you make progress in the short term while achieving your long term health goals.

Download Zero to get started.

Payment for Zero Plus will be charged to your iTunes Account when you subscribe. Subscriptions automatically renew unless auto-renew is turned off at least 24 hours before the end of the current period. Manage your subscription by going to your Account Settings.

Read more terms & conditions:
Terms of use:
Privacy policy:

What’s New

Version 5.40.1

Hello, Zero crew -

This release includes a number of bug fixes and performance improvements.
If you have any feedback or questions, please contact our Support team at

Ratings and Reviews

4.8 out of 5
435.1K Ratings

435.1K Ratings

reviewer0102030405 ,

Works. 30lbs in 2.5 months

I tried keto, I tried them all. Ended up binging and gaining more back quickly. Found fasting and really knocked out the cravings. With Zero it’s really easy to follow your progress without feeling like you’re staring at a clock waiting to eat again. The articles help ease your mind in the beginning knowing that your hunger pangs and other side effects are common and have reasons. Also how to avoid them and get past the fasting wall. I love the timer and how you can count up or down. I count up because I like seeing how far I can push myself within reason. Counting down makes me want to eat as soon as it hits 0:00. The app has some great tracking features and syncs up with apple health so it takes down the data from my smart scale. Nice knowing that I don’t have to manually enter everything every time. A welcomed improvement would be a way to change the theme of the app to keep it fresh or personalized. Different colors etc. this is a small ask for me. Overall I love the app and have lost 30lbs, 6%body fat in 2.5 months. Tbh I haven’t exercised much at all. Just having my body do what it does and use the energy I’ve stored away for years. But now losing the weight of nearly two full size dyson vacuums, I have more energy both mentally and physically that I now crave to get out and do more

Mattiekinsss ,

Updated: Room for Improvement

21 Nov Update: The developers reached out to me from my initial review and were super helpful and were able to walk me through how to better navigate the app. My lack of understanding how to fully use all the features is why I struggled to change fast settings without saving it as a preset. Due to their amazing response, explanations and helping me fix my complaints deserves 5 stars. It’s definitely worth the subscription and has earned 5 stars in my book.👌🏾 I can recommend this app 100% ⭐️⭐️⭐️⭐️⭐️
It’s ok, I love the majority of the features. & unfortunately I forgot to cancel after my free trial. But it’s not worth $70/year. I don’t understand why there isn’t an option to shift or plug in a fast without having to make it a preset. Life happens and I sometimes do an odd hour fast just to get back on track. But that doesn’t mean I want it to be saved as a preset. You should have the option to just put in a fast without being forced to save it as a template. They’re typically one off fasts. The lack of flexibility there is annoying. It’s also odd that it’s not an option under the premium section. If I’m paying to track my fasts it should be a bit more flexible for the price we’re paying. I’ll look for another app that has this simple feature. It’s great aside from that.

Developer Response ,

Hi there – Thanks for takiing the time to provide this feedback.

If you'd like a refund please visit the following link and choose 'Billing & Subscriptions' then 'Request a Refund":

Good news! There's no need to make it a preset. If you'd like to fast longer than your goal, go ahead and when you've reached your desired duration, tap the end button on the timer. If you'd like to set a shorter goal (1) tap the small number in the circle just above the timer and to the right (2) tap 'Custom Fast' (instead of tapping a space under 'Your Presets') (3) choose the duration (4) tap 'Load Fast' (if not in a fast already) or 'Change Fast'(instead of 'Save As Preset') if no fast is running on the timer.

If you'd like help with these items or anything else in the app please email us at with the details and include reference #68995 and our support team will assist you directly.
–Team Zero

Msatx ,

Literally life changing!

This app has been literally life changing! I accidentally stumbled upon it, just wanted something SIMPLE to log my fasting hours when I first started learning about intermittent fasting but it has sparked my interest in all things related to fasting and health. Im not able to afford paid version and Im extremely grateful that the free version has enough basic information and tracking features to inspire change and at least plant that seed to help people want to learn more, and to want to live with more insight, regardless of economic situation. I was that moron.. the one watching with suspicion while wolfing down pizzas, thought people fasting were just weird food hating extremists. This app has been a revelation, and has been instrumental in opening the door to a new world to me so to speak. It has been invaluable in changing my attitude towards food, fasting, meditation. If you have the means to buy the paid version do it, it will be a small investment for what you get. For me sadly the the price point for the paid version for this and the podcast is not doable but the free version can be very eye opening. Dont just log fasts like I did at first. Dive in and discover everything on the app thats available for free and listen to the podcasts. Fasting and tracking my glucose is now my normal way of life. Grateful.

App Privacy

The developer, Zero Longevity Science, Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Linked to You

The following data may be collected and linked to your identity:

  • Health & Fitness
  • Location
  • Contact Info
  • User Content
  • Identifiers
  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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