Zero is the fasting app most people start with, and the one most people eventually feel is doing more than they asked for.

Underneath, a fasting tracker is a clock with a start button. Here are eight alternatives, and an honest look at whether the extra features are worth a subscription.

How this list is sourced

I have not run eight fasting apps in parallel, and neither has any other blog that says it has.

Every developer name, star rating and rating count below was verified against the US App Store on 11 August 2026. All of them, Zero included, are free to download.

I’m not quoting subscription prices. Fasting app pricing changes by region, by promotion, and by which paywall variant you happen to land in. Numbers in this category have been some of the most wrong on the internet. Check the price in the App Store listing before you subscribe to anything, including any app I mention.

Two corrections worth having up front

You can export your Zero data. A lot of “leave Zero” articles claim you can’t. Zero’s own support documentation describes a “Download My Data” option in the Me tab, which emails you a password-protected zip. The files come out as JSON rather than CSV, so it’s not a one-click import into another app, but your history is not held hostage. That changes the calculation on switching.

Be careful with “Life Fasting Tracker” recommendations. The LIFE Fasting Tracker that older articles point you at was built by LifeOmic. It was removed from Google Play in June 2024, and an App Store search on 11 August 2026 does not return a LifeOmic app. What does come back under that name is from a different developer with a few hundred ratings. It’s not the app the older recommendation meant.

What Zero actually is

Zero: Fasting & Food Tracker, from Zero Longevity Science, Inc. 4.8 stars across 445,269 ratings, free to download with a subscription on top. It was founded by Kevin Rose and has leaned harder into longevity content and food logging over the years.

Free tier: fasting timer, limited history, basic zone display, community. Paid tier: unlimited history, full zone detail, coaching and educational content, deeper insights, custom fast types.

What it’s genuinely good at: it is the best-produced app in the category, the content is written rather than generated, and the zone visuals are the reason most people can explain what a 16:8 is at all.

Where people bounce: the free tier is deliberately thin, the upsells are frequent, and if all you wanted was a timer, you are being sold a longevity platform.

The uncomfortable bit: fasting zones

Every app here sells you a coloured ring that says you’ve entered “fat burning” or “ketosis” or “autophagy” at a particular hour. Read that ring for what it is.

Autophagy is real. It’s a well-studied cellular recycling process, and Yoshinori Ohsumi won the 2016 Nobel Prize in Physiology or Medicine for working out its mechanisms.

The clock on your phone is not measuring it. No consumer app can detect autophagy, ketosis or anything else happening in your cells. It is running a countdown from when you pressed start. The hour markers come largely from animal and cell studies, and the human timing varies with your last meal, your activity, your body composition and your metabolic health. Two people at hour 17 are not in the same state.

The zones are a motivational interface. That’s not nothing, and it’s not a measurement. Any app that implies otherwise is overselling, and so is any article that treats “reaches autophagy at 16 hours” as a checkable fact.

Quick comparison

Verified on the US App Store, 11 August 2026. All free to download, all with paid tiers unless noted.

AppDeveloperRatingRatings
Zero: Fasting & Food TrackerZero Longevity Science, Inc.4.8445,269
Simple: AI Weight Loss CoachAM APPS LTD4.7393,509
Fastic Weight Loss & FastingFastic GmbH4.8246,125
BodyFast: Intermittent FastingBodyFast GmbH4.7145,061
FastEasy: Intermittent FastingWELLTECH APPS LIMITED4.778,858
Fasting Tracker & Diet AppHendrik Folkerts4.612,284
Window - Intermittent FastingMosaic S.r.l.4.510,598
Fastin: Intermittent FastingBONGMI LIMITED4.810,162
Sunrise - Intermittent FastingArbor Apps LLC4.89,686

Rating counts matter more than the stars here. A 4.8 across 445,000 ratings and a 4.8 across 9,686 are very different levels of evidence.

If you want the big-app experience without Zero

Fastic — 4.8 stars, 246,125 ratings

Developer: Fastic GmbH. The closest like-for-like to Zero in scope: timer, zones, water and step tracking, food logging, education, a large user base.

Switch here if you like having a whole programme around the fast and simply didn’t get on with Zero’s version.

Simple — 4.7 stars, 393,509 ratings

Developer: AM APPS LTD. The second most-rated app in this list. Fasting sits inside a broader weight and habit coaching product with a chatbot layer.

Switch here if the fasting window was always a means to a weight goal, and you want the app to talk about the goal.

BodyFast — 4.7 stars, 145,061 ratings

Developer: BodyFast GmbH. Built around fasting plans and weekly coaching plans rather than an open-ended timer you configure yourself.

Switch here if you want to be assigned a schedule instead of designing one.

If you want less app, not more

Window - Intermittent Fasting — 4.5 stars, 10,598 ratings

Developer: Mosaic S.r.l., the studio behind the habit tracker Productive. The name is the product: it’s about the eating window, presented plainly.

Note the rating, which is the lowest here. Smaller and less polished than the big four, and that’s roughly the point.

Sunrise - Intermittent Fasting — 4.8 stars, 9,686 ratings

Developer: Arbor Apps LLC. A straightforward tracker with a clean timer and history, without the food-logging apparatus.

Fastin - Intermittent Fasting — 4.8 stars, 10,162 ratings

Developer: BONGMI LIMITED. Timer, zones, history, widgets. Same shape as the big apps at a fraction of the surface area.

FastEasy — 4.7 stars, 78,858 ratings

Developer: WELLTECH APPS LIMITED. More rated than the three above, still narrower than Zero.

Fasting Tracker & Diet App — 4.6 stars, 12,284 ratings

Developer: Hendrik Folkerts. An independent developer’s app rather than a studio product, which usually means fewer features and fewer upsells.

And the option nobody sells you

Your phone’s clock. Set an alarm for when the window opens. That’s the whole mechanism. No zones, no history, no streak, no subscription.

If you’ve been fasting for months and know your schedule, this genuinely works, and it’s worth naming because every app on this page has a commercial reason not to mention it. What you lose is the history, and history is the one feature that actually changes behaviour over time for most people.

Do you need a paid tier at all?

Probably not if:

  • You already know your schedule and keep it
  • You want a timer and a log, not a curriculum
  • You’re self-motivated and the streak is your only feedback

Possibly yes if:

  • You’re new and want the education in one place rather than scattered across YouTube
  • Long-term history and trends genuinely change what you do
  • You want food logging and fasting in the same app

The honest framing: the paid tiers here mostly sell content and analysis, not a better timer. If you’re paying to learn, that can be fair value. If you’re paying for a countdown, look at the list above.

Switching without losing your history

Export from Zero first. Use Download My Data in the Me tab before you cancel anything. You’ll get JSON files by email, which are readable and archivable even if no app imports them directly.

Expect to start at zero everywhere else. No app on this list offers a clean import from another tracker. Your streak does not travel.

Don’t cancel on day one. Run the new app alongside for a week. Fasting apps differ mostly in how the timer behaves when you’re half asleep at 7am, and you can’t tell that from a screenshot.

FAQ

Is Zero worth paying for? If you want the education and the food tracking, it’s the best-made product in the category. If you want a timer with a history log, you’re paying for things you won’t open.

Can I export my data from Zero? Yes. Zero’s support documentation describes a Download My Data option in the Me tab that emails you a password-protected zip. It arrives as JSON, not CSV, so no other app will import it directly, but you keep the record.

What’s the best alternative to Zero? Fastic if you want the same broad feature set, Simple if your real goal is weight, Sunrise or Fastin if you want a plain tracker. All are free to download.

Does the free version of Zero work? Yes, for tracking a fast. The limited history is the constraint that pushes people to subscribe.

Do fasting apps actually detect ketosis or autophagy? No. They run a timer and label the hours. Nothing on your phone is measuring your cells.

Is 16:8 the right schedule? It’s the most common one because it fits a normal day, not because it’s been shown to be optimal. Intermittent fasting research is still developing, and results vary between people. Talk to a doctor before starting if you take medication, are pregnant, or have a history of disordered eating.

Related reads:

Disclosure: FastTrack is mine

I build iOS apps, and FastTrack is one of them.

It does not appear in the comparison table, in the eight ranked alternatives, in the switching advice, or in any FAQ answer on this page. Scoring my own product against apps I compete with isn’t a fair test, and you shouldn’t have to take my word for it. If a plain fasting timer with history and no subscription is what you want, it exists alongside the eight apps listed here. It is new and has very few App Store ratings so far, so there is not much of a crowd verdict to lean on either. Try it and judge for yourself.

Sources

This article is general information, not medical advice. Talk to a qualified professional about anything affecting your health.

— Dolce