Comparison

Fast Slow vs Fast Track Pro

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • 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
Features
Read full description

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. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://cernezan.com/fast-slow/privacy/

About

Fast Track Pro

Features
Read full description

FastTrack Fasting helps you build an intermittent fasting routine you can repeat across iPhone, iPad, Apple Watch, widgets, and Shortcuts. Start your 7-day free trial and unlock everything: choose common plans like 16:8, 18:6, 20:4, or OMAD, start a fast in one tap, pause or resume when life changes, and review your history as you build consistency. During a fast, FastTrack Fasting shows elapsed time, remaining time, educational fasting-window estimates, reminders, hydration tools, and a clear completion flow. Premium unlocks the deeper routine-building toolkit: - Custom fasting protocols - Advanced fasting statistics and weekly insights - Achievements and streaks - Private progress photo journal - Data export - Apple Health body-measurement sync for weight and body fat percentage Your data stays private by design. FastTrack Fasting stores fasting data on device, uses Apple Health only with permission, does not use ad tracking, and uses App Store billing for purchases and restores. FastTrack Fasting is for wellness tracking and education. It is not a medical device and does not diagnose, treat, or prescribe. Consult a qualified professional before changing fasting or nutrition habits, especially if pregnant, managing a medical condition, taking medication, under 18, or under clinical supervision. Note: FastTrack is designed for wellness tracking and is not a medical device. Consult your healthcare provider before starting any fasting regimen. Privacy Policy: https://fasttrack.duttlabs.app/privacy.html Terms of Service: https://fasttrack.duttlabs.app/terms.html Support: https://fasttrack.duttlabs.app/support.html

Screenshots

Fast Slow4 screens
Fast Track Pro4 screens

Verdict

The call

The clearest difference is update cadence: Fast Slow at every 2 weeks against Fast Track Pro's every 3 months. Fast Track Pro's advantage is device support (3 vs 1). On price, ads, in-app purchases and iOS requirement 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Fast Slow sells 4 in-app purchases, starting at $1.99 per 7 days and Fast Track Pro sells 3 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Fast Slow ships an update every 2 weeks, Fast Track Pro every 3 months. The most recent releases landed on October 17, 2026 and October 13, 2026 respectively.

Scorecard2 real differences · 8 level
Fast Slow versus Fast Track Pro: the parameters behind the verdict, then further details
ParameterFast SlowFast Track Pro
PriceFreeFree
Rating5.0 (36 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings36 — better—
Update frequencyEvery 2 weeks — betterEvery 3 months
AdsNoNo
In-app purchasesYesYes
MonetizationFree—
DevicesiPhoneiPhone, iPad, Apple Watch — better
Requires iOS18.017.0 — better
Further details — not scored
Size23 MB6 MB
Age rating4+4+
DeveloperZan CerneShankar Dutt

In-app purchases

4 purchases

Fast Slow

Subscriptions2
  • Legacy$1.997 Days
  • Legacy - Yearly3 Days trial$12.991 Year
One-time2
  • Buy Me a Coffee$2.99
  • You're Amazing$9.99
3 purchases

Fast Track Pro

Subscriptions2
  • FastTrack Premium Monthly7 Days trial$4.991 Month
  • FastTrack Premium Yearly7 Days trial$24.991 Year
One-time1
  • FastTrack Lifetime$49.99

Questions

Is Fast Slow free?
Fast Slow is free to download, with in-app purchases available.
Is Fast Track Pro free?
Fast Track Pro is free to download, with in-app purchases available.
Do Fast Slow or Fast Track Pro have ads?
Neither Fast Slow nor Fast Track Pro shows ads.
Which is updated more often, Fast Slow or Fast Track Pro?
Fast Slow ships an update every 2 weeks, and Fast Track Pro every 3 months. Most recently, Fast Slow was updated on October 17, 2026 and Fast Track Pro on October 13, 2026.

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