Atomic Fast vs Primal Fast
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Atomic Fast
This app combines intermittent fasting with AI-powered calorie and macro tracking. It analyzes your eating patterns, hydration, sleep, and activity to provide metabolic insights and a daily readiness score. Seamlessly integrates with Apple Health for a holistic view of your well-being.
- AI calorie and macro estimation from photos
- Intermittent fasting timer with metabolic phases
- Break-fast meal scoring and suggestions
- Connects meals and fasts for holistic insights
- Daily readiness score based on health signals
- Apple Health and Apple Watch integration
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Track your fasts through real metabolic phases, then snap a photo of your meal to log calories and macros in seconds — and see exactly how the two connect. Most fasting apps track time; most calorie apps track food. Atomic Fast connects both. Atomic Fast combines intermittent fasting, AI calorie tracking, macro counting, Apple Health insights, and hydration tracking in one app — made for people who already fast and want more than just a basic timer or food diary. FASTING TIMER WITH METABOLIC PHASES Track your fasts with a real-time fasting timer and estimated metabolic phase guidance. Follow your progress through clear visual stages, from digestion and transition to glycogen depletion, fat burning, ketosis, deeper fasting, and autophagy. Choose popular fasting schedules like 16:8, 18:6, 20:4, OMAD, or create your own custom plan. Adjust your goals anytime, and get fasting milestone notifications without the pressure. AI CALORIE TRACKING IN SECONDS Take a photo of your plate. Atomic Fast typically identifies foods in under 5 seconds and estimates calories, macros, and nutrients — like a smart AI calorie counter and macro tracker that actually understands what you ate. You can also log meals by: - Describing what you ate with text or voice - Scanning nutrition labels - Scanning barcodes - Searching the USDA food database - Adding meals manually when needed No more typing one ingredient at a time. BREAK-FAST SCORE The first meal after a fast matters. Atomic Fast scores your break-fast meal from 0 to 100, with practical suggestions on protein, fiber, carbs, and balance for a smoother transition back into eating. MEALS AND FASTS THAT WORK TOGETHER Most fasting apps track time. Most calorie trackers and food diaries track food. Atomic Fast connects both. See how your last meal affects your next fast, how your fasting consistency affects your eating patterns, and how nutrition timing may connect with sleep, recovery, and daily energy. METABOLIC INSIGHTS Atomic Fast helps you spot patterns across fasting, meals, hydration, sleep, heart rate, HRV, activity, and more. Interactive charts and daily insights help you understand habits like calorie trends, macro balance, fasting consistency, and how nutrition timing may connect with sleep, recovery, and energy levels. Daily insight examples: - "Ending eating by 7 PM dropped your sleeping heart rate by 4 bpm last week" - "On high-recovery days you hit your fasting goal 30% more often" Insights are calculated on your device. Your patterns stay yours. DAILY READINESS SCORE Wake up to a readiness score from key health signals: sleep, HRV, resting heart rate, activity, exercise, and respiratory rate. A simple guide to whether today is a good day to push your fast, stay normal, or focus on recovery. APPLE HEALTH AND APPLE WATCH Atomic Fast syncs 24 Apple Health data types: sleep, heart rate, HRV, steps, workouts, weight, respiratory rate, and more. Meals write 11 nutrients plus water back to Apple Health, keeping your nutrition data connected across your favorite health apps. HYDRATION TRACKING One-tap water logging. Smart reminders that fit naturally around your fasting routine. BUILT FOR EVERYDAY USE - Three themes including a signature Deep Purple mode - Two timer styles: Atomic Ring and Classic Ring - Smart notifications for fasting milestones, hydration, meal reminders, and weekly recaps - Awards and streaks to celebrate progress without pressure - Offline-first experience - Privacy-focused design - Apple Watch companion app ATOMIC+ The free version is the real product — fasting tracking, manual food logging, readiness score, daily insights, themes, and 7 AI meal scans per week, all free and ad-free. Atomic+ unlocks: - Unlimited AI meal scans - iCloud backup and data export Available as Atomic+ Monthly, Atomic+ Annual (with 7-day free trial), or Atomic+ Lifetime. Terms of Use: https://atomicfast.com/terms Privacy Policy: https://atomicfast.com/privacy
Primal Fast
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Primal Fast — The fasting tracker built for carnivore & animal-based living. Most fasting apps treat you like everyone else. Primal Fast is different — built from the ground up for people eating carnivore, animal-based, or keto. BUILT FOR YOUR DIET Choose your eating style during setup and get a fasting plan tailored to how you actually eat — not generic advice for salads and smoothies. SIMPLE, POWERFUL FASTING TIMER Pick your protocol — 16:8, 18:6, 20:4, OMAD, or set your own custom window. Watch your progress with a live timer that tracks your fasting stages in real time, from "Fat Burning Begins" to "Deep Ketosis." STAY MOTIVATED WITH STREAKS Build daily fasting streaks, track your longest fast, and see your weekly summary at a glance. WATER TRACKING Quick-tap water logging to stay hydrated during your fasts. REAL PROGRESS, REAL DATA Log your weight, set a target, and watch your progress bar fill up. Your weekly summary shows days fasted, average duration, and total fasting hours — all calculated from your real activity. SMART REMINDERS Get notified an hour before your eating window opens, and again when your fast is complete. Reminders are optional — you're always in control. NO HIDDEN FEES Try Primal Fast free for 7 days. We show you exactly when your trial ends and when billing starts — no surprises, no fine print. Whether you're doing carnivore, animal-based, keto, or just want a fasting app that doesn't feel like it was built for someone else — Primal Fast is for you. Download now and start your primal journey. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is update cadence: Atomic Fast at every 4 days against Primal Fast's every 8 days. Primal Fast's advantage is iOS requirement (15.1 vs 18.0). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Atomic Fast sells 3 in-app purchases, starting at $4.99 per month and Primal Fast sells 2 in-app purchases, starting at $6.99 per month. Whichever you choose, the download price is not the number that matters.
Atomic Fast ships an update every 4 days, Primal Fast every 8 days. Both last shipped on October 28, 2026.
| Parameter | Atomic Fast | Primal Fast |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (30 ratings) — better | — |
| Positive reviews | 96.3% of reviews | — |
| Number of ratings | 30 — better | — |
| Update frequency | Every 4 days — better | Every 8 days |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Freemium | — |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Requires iOS | 18.0 | 15.1 — better |
| Further details — not scored | ||
| Size | 22 MB | 43 MB |
| Age rating | 4+ | 4+ |
| Developer | Startise | SERGEI JELUASVILI |
In-app purchases
Atomic Fast
- Atomic+ Monthly$4.991 Month
- Atomic+ Annual7 Days trial$29.991 Year
- Atomic+ Lifetime$59.99
Primal Fast
- Primal Fast Pro — Monthly$6.991 Month
- Primal Fast Pro — Annual7 Days trial$34.991 Year









