FastingCat vs Fast Slow
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
FastingCat
Master intermittent fasting with a focused timer and science-backed tracking. Monitor your progress with detailed insights, charts, and smart notifications to stay motivated and in control of your fasting journey. Your privacy is prioritized with on-device data storage and no ads.
- Customizable fasting presets
- Science-backed fasting zone tracking
- Detailed progress charts
- Flexible scheduling with grace days
- Smart notifications
- Seamless weight logging
- On-device data privacy
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FastingCat is the fast, focused way to master intermittent fasting and watch the scale move. The app puts clear metrics and practical tools in your pocket so you can stay consistent, motivated and fully in control—for absolutely free. Why FastingCat? • Simple setup: pick a preset (16-8, 18-6, 20-4, 24-hour, alternate-day or create your own) and start the timer with one tap. • Science-backed tracking: see exactly when you move from Anabolic to Catabolic, Fat Burning, Ketosis, Deep Ketosis and Autophagy. • Deep insights at a glance: total fasting hours, completed fasts, streak length, best streak, grace days used, weight change and more. • Rich charts: overlay weight and fasting windows, follow your progress week over week and celebrate each downward trend. • Flexible scheduling: choose specific weekdays or let FastingCat ignore a set number of grace days so real life never breaks your streak. • Smart notifications: get reminded when your eating window closes, when a zone switches or when it is time to break your fast. • Seamless weight logging: import weight from the Health app or type manually; all data stays on device. • No account required, no ads, no cloud storage. Your privacy stays yours. Power users can: • Fine-tune presets with second-level precision • Track progress in both metric and imperial units How we keep you motivated • Streak tracking rewards consistency • Milestone badges for total hours and longest fast • Detailed fasting zone timeline so you can actually “see” ketosis flip on • Fast completion reports you can share anywhere Who is FastingCat for? • Beginners starting a weight-loss journey • Athletes cutting fat without losing muscle • Biohackers chasing autophagy benefits • Anyone who wants a distraction-free fasting timer with serious stats Disclaimer FastingCat is a lifestyle tracker, not medical advice. Intermittent fasting may not suit everyone. Consult a qualified healthcare professional before making any dietary or exercise changes. Privacy and Terms Your data never leaves your device unless you choose to export it. See the full policies: • Privacy Policy: https://sites.google.com/view/fastingcat-privacy-policy/home • Terms of Use: https://sites.google.com/view/fastingcat-terms-of-use/home
Fast Slow
Understand your body's metabolic changes during fasting with a visual timeline. This free app guides you through different fasting zones, from digestion to deep ketosis, and offers customizable schedules and smart notifications. It provides stats, streaks, and widgets for easy progress tracking.
- Fasting timer with visual timeline
- 6 customizable fasting schedules
- 5 distinct fasting zones explained
- Smart notifications for fasting windows
- Stats, streaks, and trends tracking
- Home and Lock Screen widgets
- Siri Shortcuts integration
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See what happens inside your body as you fast. Fast Slow walks you through 5 fasting zones, from digestion through fat burning to deep ketosis, so you understand what every hour of your fast is doing. 100% free. Every feature. No ads. No paywalls. No trackers. Free forever. WHAT MAKES FAST SLOW DIFFERENT Most fasting apps just count down a timer. Fast Slow shows you what's actually happening in your body at each stage: - Anabolic (0-4h): Digesting and storing nutrients - Catabolic (4-8h): Tapping into energy reserves - Fat Burning (8-12h): The metabolic switch - Ketosis (12-16h): Ketones and cellular cleanup - Deep Ketosis (16h+): Deep cellular renewal Tap any zone to learn more about the science behind it. 100% FREE. EVERY FEATURE INCLUDED. No premium tier. No trial that expires. No paywall gates. Every feature in Fast Slow is yours from day one: - All 6 fasting schedules - All stats, streaks, and trends - All widgets (Home Screen and Lock Screen) - All notifications - Siri Shortcuts - iCloud sync - Data export Everything free. No catches. FEATURES Fasting Timer One tap to start. One tap to stop. A visual timeline shows where you are, what zone you're in, and what comes next. 6 Fasting Schedules 12:12 for beginners, 14:10, 16:8 (the most popular), 18:6, 20:4, and OMAD (one meal a day) for experienced fasters. Visual Timeline Color-coded timeline of your fasting and eating windows. Plan meals, training, and recovery at a glance. Smart Notifications 7 notification types: goal reached, halfway there, one hour left, eating window alerts, and a custom last meal reminder. Nudges, not nags. Stats & Streaks Total fasts, average duration, personal records, weekly trends, and a monthly fasting calendar. Small wins add up. Widgets Home Screen and Lock Screen widgets with progress rings, timelines, and live timers. Check your fast without opening the app. Siri Shortcuts "Hey Siri, start my fast." Start, stop, and check your fasting status hands-free. AI-Powered Greetings On supported devices, Apple Intelligence creates personalized messages based on your fasting progress, streak, and time of day. iCloud Sync Your fasting data syncs automatically across all your devices. Data You Own Export your fasting history as JSON. Delete everything with one tap. Your data, your choice. DESIGNED FOR REAL LIFE Pick a schedule, adjust as needed, and let Fast Slow handle the timing. New to fasting or already have a routine, it works either way. Structure when you want it, out of the way when you don't. Built by one developer who fasts every day. No corporate agenda. No growth hacking. A well-made tool that respects your time and your data. RESPONSIBLE APPROACH Intermittent fasting can support weight management, energy, and focus, but results vary. Fast Slow provides tools and information, not medical advice. If you have health conditions, are pregnant, or have a history of eating disorders, please talk to a healthcare professional before starting.
Screenshots
Verdict
The clearest difference is monetization model: Fast Slow at free against FastingCat's free with in-app purchases. FastingCat's advantage is update cadence (every 6 days vs fortnightly). On price, rating, review sentiment and ratings volume 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. FastingCat sells 10 in-app purchases, starting at $0.99 per month and Fast Slow sells 4 in-app purchases, starting at $1.99 per 7 days. Whichever you choose, the download price is not the number that matters.
On the App Store both sit at effectively the same score — 4.9 for FastingCat against 5.0 for Fast Slow. Both are backed by a comparable volume of ratings — 55 and 22 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
FastingCat ships an update every 6 days, Fast Slow fortnightly. The most recent releases landed on August 7, 2026 and September 13, 2026 respectively.
| Parameter | FastingCat | Fast Slow |
|---|---|---|
| Price | Free | Free |
| Rating | 4.9 (55 ratings) | 5.0 (22 ratings) — better |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 55 — better | 22 |
| Update frequency | Every 6 days — better | Fortnightly |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone | iPhone |
| Requires iOS | 17.0 — better | 18.0 |
| Further details — not scored | ||
| Size | 24 MB | 19 MB |
| Age rating | 4+ | 4+ |
| Developer | ProApps Solutions | Zan Cerne |
Customer experience
FastingCat
Fast Slow
In-app purchases
FastingCat
- Monthly Donation (Cookie)$0.991 Month
- Monthly Donation (Donut)$2.491 Month
- Monthly Donation (Smoothie)$4.991 Month
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- Monthly Donation (Salad)$7.991 Month
- Monthly Donation (Protein)$9.991 Month
- One-time Donation (Coffee)$1.99
- One-time Donation (Sandwich)$4.99
- One-time Donation (Pizza)$9.99
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- One-time Donation (Groceries)$24.99
- One-time Donation (Books)$49.99
Fast Slow
- Legacy$1.997 Days
- Legacy - Yearly3 Days trial$12.991 Year
- Buy Me a Coffee$2.99
- You're Amazing$9.99









