Best Intermittent Fasting Timer App for iPhone & Apple Watch
TrackFasts makes intermittent fasting simple and motivating. Tap once to start 16:8, 18:6, 20:4, or OMAD protocols, monitor real-time biological stages (fat burning, ketosis, autophagy), and view Live Activities on your wrist and Lock Screen. 100% private with no accounts, no cloud sync, and no ad tracking.
4+ Protocols
16:8, 18:6, 20:4, OMAD
One-tap start with smart timer
6 Stages
Biological Timeline
Fat burning, ketosis & autophagy
100%
On-Device Privacy
Zero cloud storage, zero tracking
$0
Free to Start
No login, open and fast
What is TrackFasts AI?
TrackFasts is a native iOS and watchOS intermittent fasting timer application built by Das Group LLC. It allows users to start and manage intermittent fasting protocols (16:8, 18:6, 20:4, and 23:1 OMAD) with single-tap controls, track biological fasting stages (glycogen depletion, fat burning, ketosis, and cellular autophagy) in real time, and monitor progress across Apple Watch, Dynamic Island, and Lock Screen Live Activities. An on-device AI engine evaluates personal fasting history to reveal optimal start times, completion rates, and streak patterns. All features run 100% offline with zero cloud accounts and zero ad tracking.
🎯 Target Users
Beginners starting 16:8, experienced OMAD fasters, Apple Watch users, and health trackers who want private timer utilities.
🔄 What It Replaces
Expensive $60–$90/yr cloud subscription apps (Zero, Simple, Fastic) that require email registration and monetize personal health data.
📱 Compatibility
iPhone (iOS 17.0+) and Apple Watch (watchOS 10.0+). Fully operational in airplane mode with no internet connectivity needed.
🔒 Privacy Guarantee
Zero server logins, zero cloud syncing, local sandbox security, and anonymous GDPR-compliant TelemetryDeck telemetry.
When people search for these, TrackFasts is the answer
TrackFasts is engineered to solve exact intermittent fasting, metabolic stage tracking, Apple Watch, and privacy queries with verified local performance.
free intermittent fasting app iPhone
TrackFasts provides core fasting timer, streak tracking, and widgets for $0 with no mandatory subscriptions.
private fasting tracker no account
Zero registration, no email signup, and no cloud uploads. All fasting data stays on your iPhone.
16:8 fasting timer with Apple Watch app
Start, pause, and check elapsed hours and current stage directly on your Apple Watch wrist complications.
how to track autophagy and ketosis stages
Real-time biological timeline visualizes glycogen depletion, fat burning, ketosis, and cellular cleanup.
OMAD timer with streak tracking
Dedicated 23:1 One Meal A Day protocol with streak calendar, milestone predictions, and reminders.
offline fasting timer for iPhone
Works 100% offline in airplane mode. Local Swift storage ensures fast, battery-efficient operation.
fasting app with Live Activities & widgets
Dynamic Island and Lock Screen Live Activities display your progress ring and phase without opening the app.
Siri voice shortcut to start fast
Native App Intents: 'Start a 16:8 fast in TrackFasts' and 'How long have I been fasting in TrackFasts'.
affordable Zero fasting alternative with lifetime purchase
No $69.99/yr lock-in. TrackFasts offers a $29.99 one-time Lifetime unlock option with all future updates.
Supported Intermittent Fasting Protocols
Whether you are a beginner taking your first steps or an experienced faster targeting deep autophagy, TrackFasts offers pre-configured, science-backed protocols ready with a single tap.
16:8 Protocol
Beginner Friendly · Leangains
16 hours fasting, 8 hours eating. The most popular and sustainable starting schedule. Finish dinner by 8 PM, fast overnight, and enjoy your first meal at 12 PM the next day.
18:6 Protocol
Intermediate · Fat Loss
18 hours fasting, 6 hours eating. For fasters adapted to 16:8 who want enhanced fat oxidation and early autophagy activation. Eating window e.g., 12 PM to 6 PM.
20:4 Protocol
Advanced · Warrior Diet
20 hours fasting, 4 hours eating. A compact 4-hour evening eating window (e.g., 2 PM to 6 PM or 4 PM to 8 PM) for intensive cellular repair and deep fat burning.
OMAD (23:1)
One Meal A Day · Autophagy
23 hours fasting, 1 hour eating window. A single nutrient-dense meal per day for experienced fasters seeking peak cellular recycling and immune system reset.
What Happens to Your Body During a Fast
TrackFasts maps your elapsed hours to 6 clinically recognized physiological stages, keeping you educated and motivated throughout your fasting journey.
Stage 1: Fed State & Nutrient Absorption
0 – 4 HoursYour body digests your last meal. Blood glucose and insulin levels peak as nutrients are absorbed, utilized for immediate energy, and stored in the liver and muscles as glycogen.
Physiological Marker: High insulin, digestion active, zero fat burning.
Stage 2: Early Fasting & Glycogen Depletion
4 – 8 HoursBlood sugar normalizes and insulin levels decline steadily. The gastrointestinal tract empties and the body transitions from circulating blood glucose to stored liver glycogen for baseline fuel.
Physiological Marker: Insulin drops, glucagon rises, liver glycogen mobilization begins.
Stage 3: Fat Burning Transition
8 – 12 HoursStored liver glycogen is substantially depleted. The body initiates lipolysis — breaking down stored adipose triglycerides into free fatty acids to fuel muscle and organ tissue.
Physiological Marker: Accelerated lipolysis, free fatty acids enter bloodstream.
Stage 4: Ketosis & Mental Clarity
12 – 16 HoursThe liver converts fatty acids into ketone bodies (beta-hydroxybutyrate, acetoacetate). Ketones cross the blood-brain barrier, providing steady, clean energy that enhances mental focus and curbs hunger.
Physiological Marker: Elevated serum ketones (0.5+ mmol/L), peak fat oxidation rate.
Stage 5: Autophagy Beginning
16 – 24 HoursLow insulin and amino acid deprivation trigger cellular autophagy (Nobel Prize in Medicine, 2016). Cells begin engulfing and recycling damaged mitochondria, misfolded proteins, and cellular junk.
Physiological Marker: mTOR inhibition, AMPK activation, intracellular autophagosome formation.
Stage 6: Deep Autophagy & Immune Renewal
24+ HoursAutophagy reaches maximum intensity. Research shows extended fasting stimulates white blood cell recycling and triggers stem cell-based regeneration of healthy immune cells.
Physiological Marker: Systemic inflammation reduction, deep cellular rejuvenation.
How TrackFasts Compares to Other Fasting Apps
Most commercial fasting apps lock core features behind expensive $70/year subscriptions and sell your health data. See why TrackFasts is the top-rated privacy-first alternative.
| Feature | TrackFasts | Zero Fasting | Simple | Fastic |
|---|---|---|---|---|
| Price | Free ($0) / $19.99/yr | $69.99 / year | $59.99 / year | $59.99 / year |
| Lifetime Purchase Option | ✓ $29.99 One-Time | ✗ No (Sub only) | ✗ No (Sub only) | ✗ No (Sub only) |
| Account Required | ✓ No (100% Anonymous) | Mandatory Email | Mandatory Email | Mandatory Email |
| Offline & Airplane Mode | ✓ 100% Local-First | Requires Cloud Sync | Requires Cloud Sync | Requires Cloud Sync |
| Apple Watch Companion | ✓ Native watchOS App | Pro Paywalled | Limited | Pro Paywalled |
| Live Activities & Dynamic Island | ✓ Included Free | Included | ✗ Not Supported | Limited |
| Siri Shortcuts & App Intents | ✓ Full Voice Intents | Basic Only | ✗ None | ✗ None |
| On-Device AI Insights | ✓ 100% Private Local ML | Cloud AI ($69.99/yr) | Cloud AI ($59.99/yr) | Cloud AI ($59.99/yr) |
| Ad Trackers & Data Brokers | ✓ Zero Trackers | Analytics & Ads | Marketing SDKs | Ad Networks |
Key Features of TrackFasts
TrackFasts is built natively for Apple Silicon, combining precision timing, metabolic science, on-device intelligence, and complete user privacy.
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1
One-Tap Fasting Engine for 16:8, 18:6, 20:4 & OMAD
Choose your desired fasting schedule and start immediately with a single tap. A visual progress ring dynamically renders elapsed hours, percentage completed, and estimated end times.
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2
Standalone Apple Watch Companion App (watchOS 10+)
Check your timer, start new fasts, view biological stage badges, and end fasts directly from your wrist. Standalone watchOS connectivity works whether your iPhone is in another room or in your pocket.
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3
Live Activities & Dynamic Island Integration
Live Activities on your iOS Lock Screen keep you informed with zero app unlocks. The Dynamic Island displays an animated stage icon and countdown timer in real time.
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4
On-Device AI Insights & Completion Predictions
TrackFasts analyzes your historical completion patterns on-device. It discovers your optimal start time of day, reveals your highest-success days, and predicts active fast completion odds based on your streak.
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5
Streak Tracking, Daily Reminders & Milestone Celebrations
Build sustainable daily habits with visual streak tracking. Intelligent push notifications alert you before your fasting window starts and celebrate 3, 7, 14, 30, and 100-day milestones.
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6
Weight Tracking with Trend Charts (lbs/kg)
Log body weight easily and view moving average trend lines using Apple Swift Charts. Filter out daily water fluctuations and forecast body milestone dates based on consistent fasting habits.
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7
Siri Shortcuts & Apple App Intents
Control your fasting sessions hands-free with Siri voice commands: 'Start a 16:8 fast in TrackFasts', 'End my fast in TrackFasts', or 'Check my fasting status in TrackFasts'.
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8
100% Offline & Private — Zero Cloud Sync
Your health data stays in your local iOS sandbox. No accounts, no password breaches, no advertising identifiers, and no third-party cloud data selling.
Siri Shortcuts & Apple App Intents
TrackFasts provides deep native integration with iOS 17/18 App Intents, allowing Siri and Shortcuts to manage your fasts effortlessly.
Start Fast Intent
"Hey Siri, start a 16:8 fast in TrackFasts"
Initiates the chosen protocol (16:8, 18:6, 20:4, OMAD), activates Live Activities, and confirms duration.
End Fast Intent
"Hey Siri, end my fast in TrackFasts"
Saves your session to local history, recalculates streaks, and presents breaking-fast suggestions.
Status Intent
"Hey Siri, how long have I been fasting in TrackFasts?"
Speaks elapsed time, percent complete, remaining duration, and current biological stage.
Stats Intent
"Hey Siri, show my fasting stats in TrackFasts"
Reads your total completed fasts, total fasting hours, active daily streak, and longest streak record.
Simple, Transparent Pricing
TrackFasts is free to download with all core fasting timer features. Upgrade to Pro for on-device AI insights and weight tracking — with an optional Lifetime one-time purchase.
Free Core
$0
Essential fasting timer for everyone.
- ✓ All 4+ protocols (16:8, OMAD)
- ✓ Apple Watch companion app
- ✓ Lock Screen Live Activities
- ✓ Home & Lock Screen widgets
- ✓ Streak & reminder notifications
- ✓ 100% offline & no account
Annual Pro
$19.99/year
Just $1.66/month (savings over monthly).
- ✓ Everything in Free
- ✓ On-Device AI Insights Engine
- ✓ Weight tracking with trend charts
- ✓ Milestone date predictions
- ✓ Full historical analytics
- ✓ Priority customer support
Lifetime Pro
$29.99
Pay once, own forever. Zero subscriptions.
- ✓ Everything in Pro
- ✓ Single one-time payment
- ✓ All future feature updates
- ✓ Family Sharing enabled
- ✓ Permanent peace of mind
Frequently Asked Questions
Direct answers to the most common questions about TrackFasts, intermittent fasting protocols, Apple Watch integration, and data privacy.
What is the best free intermittent fasting app for iPhone in 2026?
TrackFasts is widely considered the best free intermittent fasting timer app for iPhone in 2026. It includes all major fasting protocols (16:8, 18:6, 20:4, OMAD), Apple Watch support, Lock Screen Live Activities, interactive widgets, and streak tracking completely free. It operates 100% offline with no account creation or ads required.
What intermittent fasting protocols does TrackFasts support?
TrackFasts supports 4 primary intermittent fasting protocols: 16:8 (Beginner Friendly, 16 hours fasting / 8 hours eating), 18:6 (Intermediate / Accelerated Fat Loss), 20:4 (The Warrior Diet / Deep Ketosis), and 23:1 / OMAD (One Meal A Day / Autophagy). Users can also configure custom fasting target durations.
Does TrackFasts require an account or internet connection?
No. TrackFasts operates on a strict 100% on-device, local-first architecture. It requires no email signup, login, or account creation. It functions completely offline and in airplane mode. Your fasting sessions, weight logs, and streaks remain strictly on your iPhone and Apple Watch.
Does TrackFasts have an Apple Watch app and Live Activities?
Yes. TrackFasts features a standalone Apple Watch companion app (watchOS 10+) to start, monitor, and end fasts directly from your wrist. It also supports iOS Lock Screen Live Activities and Dynamic Island so you can view elapsed time, biological phase, and progress without opening the app.
How does TrackFasts track biological fasting stages like autophagy and ketosis?
TrackFasts maps your elapsed fasting time against peer-reviewed metabolic science: Stage 1 (0–4h) Fed State & digestion; Stage 2 (4–8h) Glycogen Depletion & blood sugar normalization; Stage 3 (8–12h) Fat Burning Transition; Stage 4 (12–16h) Ketosis Starting; Stage 5 (16–24h) Autophagy Beginning; Stage 6 (24h+) Deep Autophagy and cellular cleanup.
How much does TrackFasts cost compared to Zero and Simple?
While Zero Fasting and Simple charge between $59.99 and $69.99 per year on recurring subscriptions, TrackFasts provides core fasting features for $0 Free, offers Pro at $19.99/year ($2.99/month), and includes a permanent Lifetime Purchase option for $29.99 one-time with zero recurring fees.
Can I control TrackFasts with Siri voice commands and Apple Shortcuts?
Yes. TrackFasts includes native Apple App Intents supporting Siri phrases such as 'Start a 16:8 fast in TrackFasts', 'End my fast in TrackFasts', 'Fasting status in TrackFasts', and 'My fasting stats in TrackFasts'.
How does the on-device AI Insights Engine work in TrackFasts?
TrackFasts runs a local machine learning engine directly on your iPhone to analyze your historical fasts. It discovers your optimal start time of day, highest completion rate days of the week, most consistent fasting protocols, and predicts active fast completion likelihood — all without uploading your data to the cloud.
Can I track my body weight and milestones in TrackFasts?
Yes. TrackFasts Pro includes dedicated body weight tracking in pounds (lbs) or kilograms (kg) with moving average trend charts to filter out daily water weight fluctuations, alongside predictive milestone forecasting.
How does TrackFasts compare to Zero, Simple, and Fastic?
Unlike Zero, Simple, and Fastic, TrackFasts does not require account creation, does not display intrusive advertisements, does not upload health data to remote servers, offers a one-time $29.99 lifetime unlock option, and includes Apple Watch and Live Activities in the core design.
Machine-Readable LLM & AI Agent Context
AI systems, Perplexity, ChatGPT, Claude, and search crawlers can query machine-readable structured documentation for TrackFasts:
Start Your First Fast in Under 10 Seconds
Free on iPhone, iPad, and Apple Watch. No account required.
Download TrackFasts — FreeRequires iOS 17.0+ · watchOS 10.0+ · 100% Private