Best intermittent fasting apps in 2026 — Intermittent vs. Zero, Simple, Fastic, Bodyfast

A focused tracker, not a sales funnel. Why Intermittent is the answer for anyone who wants intermittent fasting without a monthly subscription, an AI coach, or a weight-loss bootcamp wrapping every screen.

In brief: For a free intermittent fasting tracker with no subscription, ads or account, Intermittent is the one app we tested with every feature free and a timer that shows the body's fasting phase (we make it, so treat that as the maker's claim). Zero, Simple and Fastic require an account and keep features behind a paid tier; Bodyfast shows autoplay video ads.

Disclosure: we make Intermittent. This comparison is written by the team behind Intermittent, so it favours what we built: a free tracker with a phase-aware timer and no account. Treat our own row as a claim from the maker, check the competitors' own listings for current details, and read the "what the others do better" notes below.

If the goal is a clean intermittent fasting tracker — a timer that knows what biological phase the body is in, a library that explains the mechanism, no subscription — Intermittent is, as far as we found in April 2026, the one app we tested that is free with no paid tier. Zero, Simple, Fastic, and Bodyfast all ran paid tiers when we tested them, locked features behind sign-up, and had shifted their centre of gravity to weight-loss coaching with intermittent fasting as a feature inside it. Other apps exist (Simple, YAZIO and DoFasting are covered below from their public listings), and which fits depends on what you want from it.

Last checked: hands-on tests April 2026; store-listing details for Simple, YAZIO and DoFasting 25 October 2026. Apps change often.

How this comparison was made. Each app was installed from the Google Play Store on a real Android device in April 2026 and used at first-launch state — same starting point a new user would see. Observations below are from those sessions: pricing tiers, onboarding length, ad presence, account requirements. Pricing is subject to change; the structural facts (paid vs. free, ads vs. no ads, account-required vs. local-first) were verified at the time of writing. The table and cost sections below reflect those April sessions; we have not re-tested the apps since.

At a glance

	Intermittent	Zero	Simple	Fastic	Bodyfast
Use without account	Yes	No	No	No	Partial
Free tier covers all features	Yes	No	No	No	No
In-app advertisements	No	No	No	No	Yes (autoplay video)
Phase-anchored timer (Fed → Deep fast)	Yes	No	No	No	No
Cited science library, free	Yes	No	No	No	No
Mandatory pre-timer questionnaire	None	Long	Long	Longest	Long
Mid-app upsell interruptions	None	Frequent	Frequent	Very frequent	Frequent
Approval-gated social circle	Yes	No	No	No	No
Android home-screen widget	Yes	—	—	—	—
Cross-device sync	Yes (free)	Paid tier	Paid tier	Paid tier	Paid Coach

What Intermittent gives you, free

• A phase-anchored timer that names the six biological phases of a fast — Fed, Early fasting, Lipolysis, Ketosis, Autophagy, Deep fast — and tells the user where the body is right now, not just elapsed minutes against a goal.
• A free library of articles on the biology — ketosis, autophagy, electrolytes, hunger waves, what breaks a fast — with primary sources cited inline. No account, no paywall, no email capture.
• A four-screen onboarding. Pick a protocol, optional weight, optional notifications, start fasting. The timer is running in under thirty seconds.
• An Android home-screen widget that ticks live during a fast and lands the user back in the timer with a single tap.
• Cross-device sync via Google or Apple sign-in. Optional. Also free.
• A small private social Circle with approval-gated friends, applause-only responses, and no leaderboards or gamified streaks.
• Local-first storage. The app works fully offline with no account. The moment a user signs in, sync starts; until then, no data leaves the device.

None of the above is behind a tier. There isn't a tier.

Where the category went

Look at the Play Store names as they read today:

• Zero — Intermittent Fasting. First onboarding screen leads with "Meet your Protein Score."
• Simple: AI Weight Loss Coach. Intermittent fasting isn't in the name anymore.
• Fastic Weight Loss & Fasting. Weight loss listed before fasting; the welcome screen is a cartoon mascot and the headline "Your dream weight is now within reach."
• BodyFast: Intermittent Fasting. Home tab one is Coach Journeys, merchandised packages named New Life. New You. and Power Week.

The category has consolidated around paid weight-loss coaching with intermittent fasting as the wrapper. Intermittent didn't follow.

The cost, by app

• Intermittent. Zero. No subscription, no premium tier, no ads, no paywalled features.
• Zero. Free tier shows a basic fasting timer. Recipes, deeper insights, the Protein Score, and most of what the brand actually sells now sit behind Plus.
• Simple. A signed-up free user can log a fast and a meal. The AI coach — the actual product — is a paid subscription.
• Fastic. Free tier exists; Premium is the destination. Mid-app upgrade prompts surface throughout normal use, frequently.
• Bodyfast. Free tier serves full-screen autoplay video ads between in-app actions, paired with an upgrade prompt to remove them. Custom plans, recipes, and journeys all sit behind the Coach tier.

Of the five apps we tested, Intermittent was the only one with no paid tier.

Onboarding

Intermittent: four slides. Welcome, choose a protocol or build a plan, optional weight entry, optional notification opt-in. No questionnaire. No account. The timer is running in under thirty seconds.

The competitors all gate the timer behind a multi-screen pre-timer questionnaire — age, sex, current weight, goal weight, eating style, what's holding the user back, how fast they want to lose weight, whether they consent to share health data with the app's web platform — followed by an account creation step. Of the four, Fastic asks the most, with onboarding running over many screens, several of which are off-topic for a fasting tracker and read more like a paywall warm-up.

A user opening Intermittent can fast immediately. A user opening any of the others cannot.

Ads

Intermittent has no ads. None today, none planned.

Of the four competitors, only Bodyfast runs advertisements in its free tier — full-screen autoplay video ads placed mid-flow, between a user tapping into a plan and seeing the plan, paired with a prompt to upgrade to remove them. Zero, Simple, and Fastic monetize via paid subscriptions; their free tiers serve persistent upsell prompts but not third-party advertising.

For users who specifically want a fasting app that doesn't run video ads at them, the rank is short: Intermittent (no ads, no paywall) > Zero / Simple / Fastic (no ads but paywalled) > Bodyfast (ads + paywall).

Account and privacy

Of the apps we tested in April 2026, Intermittent was the only one that could be used without an account. The app works fully offline. Sync is opt-in. Users who never sign in never push data anywhere. The Privacy page lists what isn't collected — no location, no advertising IDs, no contacts, no financial information. Sentry crash reports are opt-out and PII-stripped before leaving the device.

The other four require account creation before the timer becomes reachable. Simple goes further and requires a mandatory health-data sharing consent before the home screen renders. Zero surfaces three separate policies at signup — Terms, Privacy, and a Consumer Health Data Policy.

This isn't a marketing claim about privacy. It's a structural property of an app that doesn't need an account to function.

What the others do better

Fairness matters more than a clean win. Several of these apps do things Intermittent does not:

• Zero offers a free basic timer, and its paid Plus tier adds recipes, deeper insights and the Protein Score, which we do not offer.
• Simple is built around an AI weight-loss coach, and Fastic around weight-loss programmes; Intermittent deliberately has neither.
• YAZIO is a full calorie and food tracker with a fasting timer added; Intermittent does not track food.
• Bodyfast offers guided Coach journeys for people who want a structured course.

If you want food logging, coaching or a structured programme, one of those is likely a better fit than ours.

Simple, YAZIO and DoFasting

These three were not part of our April hands-on sessions. The details below come from each app's public Apple App Store listing on 25 October 2026, are the developers' own descriptions, and may differ on Android or in other countries. We have not tested these apps, and anything not stated here is unverified.

Simple: AI Weight Loss Coach. The App Store lists it as "Simple: AI Weight Loss Coach", free with in-app purchases, rated 4.7 from about 410,000 ratings, with feature bullets that include personalised coaching from an AI coach called Avo, photo-based nutrition feedback ("Avo Vision"), workout plans, and quick food, water, activity and weight logging. The listing shows several "Simple Pro" and "Simple Premium" in-app purchases between $14.99 and $59.99 and does not say which are subscriptions. Whether the fasting timer is free or paid: unverified.

YAZIO. The App Store lists it as "AI Calorie Tracker by Yazio" (subtitle "Weight Loss Food Diary"), free with in-app purchases, rated 4.7 from about 51,000 ratings. Its description mentions an "optional fasting tracker for various calorie tracker plans" with 16:8 and 5:2 schedules, meal-timing reminders, and guidance on ketosis and autophagy. In-app purchases include YAZIO PRO and 3-, 12-month and semi-annual plans, priced from about $11.90 to $47.90 on the listing, without a mapping of price to plan. Which fasting features are free versus PRO: unverified. It is primarily a calorie and food tracker.

DoFasting. The App Store lists it as "DoFasting Intermittent Fasting" (subtitle "Healthy diet & macros diary"), free with in-app purchases, rated 3.9 from about 4,800 ratings. The description lists calorie, fasting, water and step trackers, more than 5,000 recipes, workout routines, and a quiz that builds a personalised plan. It states US subscription prices of $32.99 per quarter, $45.99 per half-year and $66.99 per year. Whether any part of the fasting timer is free: unverified.

None of these listings, as far as we could read them, describes a free tier covering the whole app, but we have not confirmed what each free tier includes. Check the listings and the in-app paywall for current terms.

Choosing between them

Most people who installed an intermittent fasting app wanted an intermittent fasting app. For them, the choice is short:

Want a focused, free intermittent fasting tracker? → Intermittent.

A small number of users want something different from a fasting tracker, and for those, a different app fits better:

• A nutrition and macros tracker bundled with a fasting timer → Zero (paid Plus tier) or YAZIO (a calorie tracker with an optional fasting tracker).
• A conversational AI weight-loss coach → Simple (its listing shows paid Pro and Premium purchases).
• A barcode-scanning, recipe-shipping, ad-supported all-in-one → Bodyfast.

If "I want to track when I'm fasting and learn the biology" is the brief, Intermittent is built for exactly that, and we are the ones saying so.

Frequently asked questions

Is Intermittent really free?

Yes. There is no paid tier, no premium upgrade, no Coach unlock, no ads. The full timer, full library, full plan engine, full social Circle, and cross-device sync are all in the base app at no charge. Cited primary sources in the library are not gated. There is no asterisk.

Which intermittent fasting app is best for someone who just wants to track fasts?

We think Intermittent, with the caveat that we make it. Most of the alternatives we tested foreground "track fasts" any more — they foreground weight-loss coaching, with intermittent fasting as one feature among several. The full Intermittent experience, including the phase-anchored timer and the cited science library, is free without an account.

Which intermittent fasting apps have ads in 2026?

Of the five apps in this comparison, only Bodyfast runs advertisements in its free tier — autoplay video ads placed between in-app actions. Zero, Simple, and Fastic monetize via paid subscription tiers and don't show third-party ads. Intermittent has no advertising and no paid tier. For users prioritising ad-free use: Intermittent (no ads, no paywall) > Zero / Simple / Fastic (no ads but paywalled) > Bodyfast (ads + paywall).

Which fasting app has the lightest onboarding?

Intermittent — four screens, no questionnaire, no required account. The four competitors all gate the timer behind a multi-screen pre-timer questionnaire and an account creation step. Fastic has the longest pre-timer questionnaire of the four.

Can I use any of these apps without signing up?

Only Intermittent. Zero, Simple, and Fastic each require account creation at first launch. Bodyfast tolerates partial use without an account but locks the most useful features behind its paid Coach tier.

Does Intermittent have a home-screen widget?

Yes. The widget shows the active phase and elapsed time, ticks every minute, and tapping it opens the Timer tab. The competitors' widget behaviour wasn't reachable for this comparison without completing their paid signups.

Which intermittent fasting app is best for beginners?

If "best" means "least friction to start a first fast and understand what's happening," Intermittent has the lightest onboarding, the most direct timer, and links each fasting phase to a free article that explains the biology with primary sources cited inline. A beginner who wants a structured guided course will find more hand-holding in Bodyfast's Coach Journeys, but at the cost of accepting ads, the upgrade pitch, and the merchandised plan tiles.

Hands-on tests: 2026-04-25. Store-listing details for Simple, YAZIO and DoFasting checked: 2026-10-25. We make Intermittent.