Simple vs Zero vs Fastic: Best Fasting Apps in 2026 (Honest Comparison)

The best fasting-only app in 2026 is Zero for its generous free tier and Zero Longevity's research credibility, with Simple close behind for anyone who wants stronger behavioral coaching and Fastic leading in Europe for its lighter nutrition overlay. But for most people actually trying to lose fat, build habits, or improve metabolic health, a combined fasting-plus-nutrition tracker like Nutrola — with a native fasting timer, eating-window tracking, 1.8 million+ verified foods, and zero ads starting at €2.50/month — tends to outperform a dedicated fasting app used alone. Fasting tells you when to eat. Nutrition data tells you what to eat. You need both to make intermittent fasting actually work.

Intermittent fasting has matured into a mainstream eating pattern in 2026. Protocols like 16:8, 18:6, OMAD (one meal a day), and 5:2 are discussed in clinical literature, used by millions of everyday dieters, and integrated into metabolic-health programs alongside continuous glucose monitoring and sleep tracking. The research is no longer fringe — time-restricted eating has documented effects on insulin sensitivity, circadian rhythm, autophagy markers, and adherence-driven weight loss.

That popularity has produced a crowded app market. Simple, Zero, and Fastic dominate the App Store and Play Store for fasting-related searches, each with tens of millions of downloads and distinct product philosophies. Choosing between them — and deciding whether a fasting-only app is even the right tool in the first place — is the subject of this guide. We will compare the three honestly, acknowledge what each does well, and then show where a nutrition-tracker-with-fasting approach like Nutrola fills the gaps that fasting-only apps leave open.

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What Should You Look for in a Fasting App?

An accurate fasting timer with clean history

The core job of a fasting app is deceptively simple: time how long you fast, save the record, and show you trends. The execution matters more than it sounds. A good fasting timer starts and stops with one tap, survives phone restarts and timezone changes without losing state, and records fasts retroactively when you forget to press start. Your history should be viewable as a weekly calendar, a monthly heatmap, and as running averages (average fast length, longest fast, current streak). Apps that bury this data behind premium paywalls or reset it at month-end are failing the basic assignment.

A wrist-based timer is the underrated feature here. On Apple Watch or Wear OS, a glanceable countdown of hours remaining in your fast changes behavior in a way a phone lock-screen widget does not. Every time you consider breaking the fast, the remaining hours are right there on your wrist. Apps without native wearable support force you to open your phone every time you want to check, which in practice means you check less often.

Education on fasting protocols

The second real job of a fasting app is teaching you how to fast safely and effectively. That means explaining the common protocols (16:8, 18:6, 20:4, OMAD, 5:2, ADF), the physiological stages your body moves through during a fast (fed state, post-absorptive, early fasted, glycogen depletion, ketosis, autophagy), and the practical skills that determine whether you stick with it — electrolytes, sleep, caffeine timing, breaking the fast without overshooting, and recognizing when to stop.

Education is where the major apps genuinely differentiate. Some take a behavioral-psychology angle with habit stacks and cognitive reframes. Others lean into longevity science and cite published research. Others focus on newbie hand-holding with short daily lessons. None is universally better; the right one depends on how you learn.

Integration with calorie and nutrition tracking

The third criterion is the one fasting-only apps consistently fail. Intermittent fasting works because it typically creates a caloric deficit — not because the clock itself is magic. If you fast for 16 hours and then eat 3,500 calories of ultra-processed food in your 8-hour eating window, you will not lose weight, and you will not improve your metabolic markers. Fasting without attention to nutrient quality and total intake can backfire, producing muscle loss, micronutrient deficits, energy crashes, and rebound eating.

The apps that recognize this combine fasting timers with real nutrition tracking. The apps that do not leave you to run two separate apps, duplicate your logging, and lose the insight that comes from seeing fasting windows and nutrition data in one place. For most users, this integration is the single most important factor in whether fasting actually delivers results.

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Head-to-Head: Simple vs Zero vs Fastic

Simple — Behavioral Coaching and Habit Design

Simple is the Palta-backed fasting app that built its reputation on behavioral psychology. The app treats intermittent fasting as a habit-change project, not a stopwatch task. You get daily readings, mood check-ins, an AI coach named Avo, a body feedback loop for symptoms and energy, and a hydration tracker that ties into your eating window. The interface is polished, the onboarding is thorough, and the app is visibly designed for users who want guidance rather than raw tools.

Simple supports all common fasting protocols, offers a light food log, and includes progress weight tracking. The AI coach is the headline feature — it answers questions conversationally, adjusts recommendations based on how you log, and nudges you when your patterns slip. For users who have tried fasting before and failed to stick with it, the behavioral framing genuinely helps.

Pricing and free tier: Simple's free tier is limited. You get a basic fasting timer and a preview of coaching, but the core of the product — the AI coach, the full content library, personalized plans, and deeper tracking — sits behind Simple Premium at roughly $40-50 per year, with frequent promotions lowering the first-year cost. It is a fasting-only app that charges fasting-app prices; the value depends on whether you actually use the behavioral features.

Zero — Longevity-Focused with a Generous Free Tier

Zero, from Zero Longevity, is the app that popularized consumer intermittent fasting in the late 2010s and remains one of the most downloaded fasting apps in the world. The brand leans into longevity science, cites research from well-known fasting researchers, and positions fasting as part of a broader metabolic-health practice rather than a pure weight-loss trick.

The product reflects that positioning. Zero's timer is clean, its protocol library is comprehensive, and its educational content is denser than Simple's — you get explainers on fat adaptation, autophagy, protein fasting, and fasting-mimicking diets, plus a journal feature that lets you log mood, weight, sleep, and symptoms alongside your fasts. Zero's community and challenges add a social layer that the other two lack at the same depth.

Pricing and free tier: Zero's free tier is the most generous of the three. The core fasting timer, basic history, all common protocols, and a meaningful chunk of educational content are available without paying. Zero Plus, the premium subscription, runs around $69.99 per year and adds personalized programs, advanced insights, expert-led content, and deeper biomarker journaling. For users who just want a reliable timer with solid education, Zero's free tier is genuinely useful on its own.

Fastic — European-Forward with Light Nutrition Overlay

Fastic is a German-origin fasting app that is especially strong in European markets. It mixes a fasting timer with lighter nutrition tracking, a water intake logger, step counting, and a content library leaning toward wellness, recipes, and gentle coaching. The visual design feels closer to a lifestyle app than a clinical tool, which some users prefer and others find a step too soft.

Fastic's distinguishing move is its attempt to bridge fasting and nutrition in one interface. You can log meals, track calories loosely, and see eating-window patterns alongside hydration and activity. The nutrition database, however, is not at the scale or verification depth of dedicated nutrition apps — it is a light overlay rather than a serious tracker. For users who want basic awareness of what they eat during their window without switching apps, Fastic gets closer than Simple or Zero. For users who need accurate macros and micronutrients, the overlay falls short.

Pricing and free tier: Fastic's free tier offers the timer and basic features; Fastic Premium runs roughly €69 per year and unlocks the full content library, personalized plans, deeper tracking, and recipe access. Pricing is comparable to Zero Plus, and slightly above Simple's baseline.

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Which Has the Best Free Tier?

If your only criterion is a free fasting timer you can use forever, Zero wins on free-tier quality. The core timer, history, all major protocols, and a useful amount of educational content are all available at no cost. You can use Zero as a permanently free fasting app and get real value.

Simple's free tier is more restrictive. The timer works, but the behavioral coaching and AI assistant — the reasons you would choose Simple in the first place — are gated behind Premium. The free version feels like a teaser rather than a usable product, which is consistent with Simple's subscription-first business model.

Fastic's free tier sits in the middle. The timer and basic nutrition overlay are free, but deeper features, the full content library, and personalized plans require Premium. If you want a free fasting timer with a touch of food logging, Fastic's free tier is serviceable; for anything more, you will run into the paywall quickly.

None of the three offers what most users actually need for free: a fasting timer plus a real nutrition tracker with verified macros and micronutrients. That combination either requires paying for a fasting app premium tier and a separate nutrition-app premium tier, or using a single app that handles both.

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The Missing Piece: Nutrition Tracking

Fasting apps answer the question when do I eat? Nutrition apps answer the question what do I eat? Both questions matter, and answering one while ignoring the other is why so many intermittent-fasting attempts stall after the first few weeks.

The pattern is familiar. Someone starts a 16:8 protocol, loses a few pounds in the first two weeks from the initial calorie reduction, then plateaus. They are still fasting diligently, still closing their eating window on time, still logging fasts in Simple or Zero or Fastic — but the scale has stopped moving. What happened is usually straightforward: the eating window slowly expanded to fit a full day's calories, or the meals inside the window drifted toward calorie-dense, protein-poor choices that fasting alone cannot compensate for. Without nutrition data, the pattern is invisible.

The opposite failure mode is also common. Someone fasts aggressively, eats too little during the window, misses protein and micronutrient targets, and loses lean mass instead of fat. Energy drops, workouts suffer, hormones shift, and the protocol becomes unsustainable. A nutrition tracker would have caught the protein deficit or the micronutrient gap in week one. A fasting-only app cannot.

A combined approach — a fasting timer tightly integrated with verified nutrition tracking — delivers better results because it lets you see the two dimensions together. You can look at a week and see not just "I fasted 16 hours on 6 of 7 days" but "I fasted 16 hours on 6 of 7 days, hit 130g protein on 5 of 7, averaged 1,850 calories, and stayed within my fiber target." That is the level of feedback that actually drives decisions.

Nutrola was built for this. The app includes a native fasting timer with the common protocols (16:8, 18:6, 20:4, OMAD, 5:2, custom), eating-window tracking, and a fasting history that sits alongside your nutrition log — not in a separate app, not as an afterthought. When your eating window opens, Nutrola is already the place you log meals. When it closes, the timer ticks quietly on your wrist. The integration is the product.

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How Does Nutrola Compare for Fasting-Plus-Tracking?

Nutrola is an AI nutrition app (iOS and Android) that added fasting support because users were already using two apps to cover both needs. Here is what you get in one place:

• Native fasting timer with 16:8, 18:6, 20:4, OMAD, 5:2, alternate-day, and custom protocols. Starts and stops with one tap. Retroactive start editing for missed logs.
• Eating-window tracker that visualizes open and closed windows across the week, with streaks, averages, and longest-fast records.
• Meal-time logging that timestamps every food entry, so you can see exactly when your window actually opened and closed versus your stated plan.
• Macro adherence during eating windows — protein, carbs, fat, and calorie targets tracked only during your eating window, with deficit and surplus views.
• 1.8 million+ nutritionist-verified foods, so the nutrition data you log during the window is accurate rather than crowdsourced guesses.
• AI photo logging in under 3 seconds — snap your first meal breaking the fast and the AI identifies foods, estimates portions, and logs verified data.
• Voice logging using natural language, which is faster than typing when you are breaking a long fast and want to log three items at once.
• Barcode scanning for packaged foods commonly used to break fasts (protein bars, yogurts, electrolyte drinks).
• 100+ nutrients tracked inside the eating window, including electrolytes (sodium, potassium, magnesium) that matter most for fasters.
• Native Apple Watch and Wear OS apps with a wrist-based fasting timer, so you can check remaining hours without opening your phone.
• 14 languages, including the European markets where Fastic dominates.
• Zero ads on any tier, free or premium — unlike several fasting apps that now serve interstitials between content screens.

The practical effect is that a typical day looks like this: wake up, the timer is still counting down your overnight fast, you check remaining hours on your watch. When the window opens, you log your first meal with a photo or voice. The app shows you how much protein, fiber, and micronutrients you have left to hit before the window closes. You log across the day, close the window when you planned to, and the timer starts again. One app. One history. One integrated picture.

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Fasting App Comparison Table

App	Free Timer	Education	Macro Tracking	Fasting Protocols Supported	Ads	Monthly Cost
Simple	Basic	Premium only	No	16:8, 18:6, 20:4, OMAD, 5:2	Limited	~$3.50-4.00/mo billed annually
Zero	Full	Partially free	No	13:11 through ADF, full library	Limited	~$5.85/mo billed annually
Fastic	Basic	Premium only	Light overlay	16:8, 18:6, 20:4, OMAD, 5:2	Limited	~€5.75/mo billed annually
Nutrola	Full	Included	Full (100+ nutrients)	16:8, 18:6, 20:4, OMAD, 5:2, ADF, custom	Never	€2.50/mo

Nutrola is the lowest monthly cost of the four, includes full macro and micronutrient tracking that none of the fasting-only apps offer, and carries zero ads on any tier. The fasting protocol support matches or exceeds the specialized apps because the fasting timer was designed from the start to coexist with nutrition logging.

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Which Fasting App Should You Choose?

Best if you want behavioral coaching and an AI companion

Simple. If you have tried fasting before and bounced off, Simple's behavioral-psychology framing and AI coach genuinely help with adherence. You will pay more for less raw tracking, but the habit-design layer is the strongest of the three fasting-only apps. Pair it with a nutrition app if you care about what you eat in the window.

Best free fasting timer with solid education

Zero. If you want a reliable, permanently free fasting timer with legitimate educational content and a longevity-science angle, Zero's free tier is genuinely useful on its own. Upgrade to Zero Plus only if you want the deeper programs and insights.

Best if you want fasting plus real nutrition tracking in one app

Nutrola. If you recognize that fasting only works when nutrient quality and total intake match the eating window, Nutrola is the single app that combines both without forcing you to run two subscriptions. Native fasting timer, wrist-based countdown, 1.8 million+ verified foods, 100+ nutrients, AI photo logging, zero ads, €2.50/month. Fastic attempts this combination with a light overlay; Nutrola delivers it with a full nutrition database.

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Frequently Asked Questions

Can I do intermittent fasting without tracking calories?

You can, and for some people it works. A compressed eating window often naturally reduces calorie intake without explicit tracking, which is why 16:8 produces results for beginners even without a food log. The problem appears after the first few weeks: appetite adapts, the eating window expands to fit a full day's food, and the weight loss stalls. Without calorie or macro data, the plateau is invisible and most people quit. Tracking is not mandatory forever, but during the first 4-8 weeks it significantly improves the odds that fasting actually produces the results you started for.

Do fasting apps track macros?

Most fasting-only apps do not track macros in any meaningful way. Simple and Zero offer light food logging at best; Fastic has a slightly deeper nutrition overlay but does not match a dedicated nutrition tracker. For accurate macro tracking during your eating window, you either need a combined app like Nutrola or a separate nutrition tracker alongside your fasting app.

Which fasting app has the best free tier?

Zero. Its free tier includes the core timer, all major protocols, basic history, and a meaningful amount of educational content. Simple and Fastic both gate their most valuable features behind premium. For permanently free fasting, Zero is the clear winner among the three.

Is intermittent fasting actually evidence-based?

Yes, when done correctly. Time-restricted eating has documented effects on insulin sensitivity, fasting glucose, and adherence-driven weight loss. The research is strongest for moderate protocols like 16:8 and 18:6, and weaker for extreme approaches like prolonged multi-day fasts without medical supervision. The key caveat is that fasting works through nutrition and total intake, not through clock magic; without attention to what you eat, the benefits are easy to lose.

Can I use a fasting timer on my smartwatch?

Zero, Simple, and Fastic all have some smartwatch support, with varying degrees of polish. Nutrola includes native Apple Watch and Wear OS apps with a wrist-based fasting countdown, so you can check remaining hours without opening your phone. Wrist-based timers meaningfully improve adherence because the remaining hours are visible every time you glance at your watch.

How does Nutrola's fasting timer compare to Zero's?

Functionally they cover the same core features: one-tap start and stop, all common protocols, retroactive editing, and history views. The difference is context. Zero's timer lives in a fasting-only app and shows you only fasting data. Nutrola's timer lives inside a full nutrition app, so your fasting history sits next to your macro trends, your micronutrient totals, your meal timestamps, and your weight data. For users who want fasting and nutrition in one view, Nutrola's integration is the differentiator.

Do I have to pay for a fasting app to get good results?

No. Zero's free tier is sufficient for most beginners who just want a timer and some education. You can combine it with Nutrola's free tier for basic nutrition tracking, or move to Nutrola's €2.50/month premium for the full fasting-plus-nutrition experience. The worst outcome is paying $70/year for a fasting app that does not track what you eat, which is the situation many users end up in after a few months.

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Final Verdict

Simple, Zero, and Fastic are all competent fasting apps with genuine strengths. Simple excels at behavioral coaching, Zero at longevity-focused education and free-tier generosity, and Fastic at a lighter European-market-friendly interface with early-stage nutrition integration. If you are certain that a fasting-only app is what you need — a clean timer, some education, no real nutrition tracking — pick the one whose philosophy matches how you learn.

For most people, though, fasting-only is the wrong category. Intermittent fasting works through nutrition, not through clocks, and running a fasting app alongside a separate nutrition app produces a fractured workflow that fails exactly when motivation dips. A combined approach — native fasting timer, eating-window tracker, 1.8 million+ verified foods, 100+ nutrients, AI photo and voice logging, native smartwatch support, 14 languages, zero ads, €2.50/month — is what actually delivers results. Nutrola was built for the user who wants the fasting protocol and the nutritional accuracy in one place. Try it free, fast deliberately, eat with real data, and see how much the integration changes what intermittent fasting can do for you.