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Tell us about you
Set age, height and weight on smooth haptic dials, in metric or imperial. Add how active you are and when you wake and sleep.
For iPhone and iPad · iOS 26
Fasting,
Fasting,
made fluid.
LeanFast picks the right fasting plan for your body, lets you shape every day of your week, and tells you what's on your plate. It all runs on your iPhone or iPad.
Free to use. No account needed. No ads, ever. iPhone, iPad and Apple Watch, in 8 languages.
3programs that ramp with you
7days, each with its own window
3‑in‑1scanner for meals, labels and barcodes
8languages, every recipe included
How it works
From “where do I start?” to your first fast in two minutes
No guesswork and no one-size-fits-all 16:8. Answer a few questions and LeanFast builds a plan that fits your body and your day.
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Get your plan
LeanFast recommends Spark, Flow or Blaze and places your eating window in your day. It also shows a realistic date for reaching your goal.
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Fast with a glance
A clear ring shows your window and how long is left. It's also on your Lock Screen, in the Dynamic Island and in widgets.
Three programs
Start where you are. Grow from there.
Each program eases you in over four weeks, so your body adapts without the crash. You can switch programs at any time.
Spark
Begin gently. An overnight fast that grows by an hour at a time.
Wk 1Wk 2Wk 3Wk 4
For beginners, older adults, and very active or lean people.
Flow
Find your rhythm. The classic 16:8, built up smoothly.
Wk 1Wk 2Wk 3Wk 4
For people with some fasting experience and a moderately active life.
Blaze
Go further. Longer fasts for a clear fat-loss goal.
Wk 1Wk 2Wk 3Wk 4
For experienced fasters. Not offered to anyone the safety check flags.
Weekly planner
Your week isn't the same every day. Your plan shouldn't be either.
Brunch on Sunday? A late dinner on Friday? Drag a day's window on a 24-hour dial and the rest of your week stays put.
- A 24-hour dial for every dayDrag the handles to resize your window, or slide the whole window. You feel a tick every 15 minutes.
- Presets and copyChoose from 12:12 to 20:4 in one tap, then copy a day to every day, weekdays or weekends.
- Rest daysTake a day off when life happens. Your streak survives, and Prism adds two Streak Shields a month.
- Reminders that matchGet a notification when your window opens and closes, following each day's schedule.
Prism Lens
Point. Read. Know what you're eating.
Lens understands three things: a plated meal, a nutrition label and a barcode. Every result gets a Fast-Friendly grade from A to E, plus advice for your eating window.
MealRecognises the dishes on your plate
LabelReads EU and US nutrition tables
BarcodeEAN, UPC and GS1 QR codes
- Runs on your deviceReading and recognition use Apple's on-device intelligence, and it works in the EU. Your photos are never uploaded.
- Traffic lights and portionsFat, saturates, sugars and salt are rated high, medium or low. Slide the portion and see calories and macros update.
EnglishFrançaisDeutschEspañolItalianoPortuguêsNederlands
Prism Kitchen & Insights
Break your fast well. See it working.
Kitchen suggests recipes that suit the moment, like a gentle break-fast when your window opens. Progress turns your data into a trend you can trust.
- 80 recipes, beautifully photographedFilter by break-fast, high protein, under 15 minutes or low carb. Scale servings and follow step by step with built-in timers.
- A trend, not a jumpy numberSmoothed weight trend, a goal forecast, a 12-week consistency heatmap, and the time you spend in each body stage.
- A coach that notices every stepNew streak, first 16-hour fast, a tough day or a weigh-in that went up: Prism Coach responds right away with encouragement and one practical tip to stay healthy and active. Over 200 moments, in your language.
- Badges to aim forEarn 17 badges for streaks, milestones, hydration and comebacks. Stopping for your health never costs you one.
- Private progress photosA before/after slider for photos that never leave your phone.
Apple Watch
Your fast, on your wrist.
Start and end fasts, watch the stage ring fill, log water and check your stages, without reaching for your phone.
- A stage ring you can read at a glanceTime fasted, the body stage you're in, and one big Start or End button.
- Complications and Smart StackPut the ring, time left or today's window right on your watch face.
- Works when your phone doesn'tStart or end a fast on a run. It syncs with the right time once your iPhone is back in range.
- Help, one tap awayFeeling unwell? The watch stops your fast and can call emergency services directly.
Works with Apple Health
Fill in your height, weight, activity and sleep in one tap. Weigh-ins from your smart scale appear automatically, and the weight and water you log are saved to Health.
Safety comes first
“I don't feel well” stops your fast, shows what to do, and calls your local emergency number in one tap. Stopping for your health never breaks your streak.
Speaks your language
English, Deutsch, Français, Español, Italiano, Português, Català and Русский, including every recipe and food name.
Inside a fast
Know what your body is doing, hour by hour
The timer marks each stage as you reach it, so the hard hours come with context and encouragement.
0 h
Digesting
Energy comes from your last meal while insulin is elevated.
4 h
Blood sugar settles
Insulin falls back. Hunger comes in waves that usually pass in 15–20 minutes.
8 h
Stored energy
Your liver releases glycogen to keep blood sugar steady.
12 h
Fat burning
The metabolic switch: your body leans more on fat for fuel.
16 h
Ketosis rising
Ketones rise, and many people notice steadier focus and fewer cravings.
18 h
Deep ketosis
Fat is a main fuel. Keep drinking water and add electrolytes if needed.
24 h
Cell renewal
Research links longer fasts with more cellular clean-up. This is for experienced fasters only.
Timings are typical and vary from person to person. This is general wellness information, not medical advice.
Everywhere on your iPhone
Your fast, one glance away
Live Activity & Dynamic Island
A countdown on your Lock Screen and in the Dynamic Island, without opening the app.
Home & Lock Screen widgets
See your ring, the time left and your current stage wherever you look.
Siri & Shortcuts
Say “Start my fast in LeanFast”. It works hands-free.
Control Center
Start or end a fast from Control Center with one tap.
Water & weight
Log water and weight in one tap, with a 7-day strip and streaks to keep you going.
Sync if you want it
Sign in with an email code to back up and restore on a new phone. Or never sign in at all.
Private by design
Your health data is yours. Full stop.
LeanFast works fully offline without an account. If you choose to sync, your data is stored in the EU and only your account can read it. You can export or delete everything from Settings.
📱Food scans are processed on your device
🚫No ads, no third-party trackers
🇪🇺Optional sync, hosted in the EU
❤️Apple Health: you choose exactly what’s shared
🗑️Delete your account in two taps
Pricing
Free to fast. Prism when you want more.
The plan, the planner, the timer and the widgets are free forever. LeanFast Prism adds Lens, Kitchen, Coach and deeper insights.
Free
€0
Forever, with no account needed
- Personal plan: Spark, Flow or Blaze
- Weekly planner with a daily dial
- Timer and body stages
- Apple Watch app & complications
- Apple Health, Live Activity, widgets, Siri
- Water and weight logging
- Badges and coach encouragement
- 3 free Lens scans
Monthly
€3.99
per month · cancel anytime
- Everything in Free
- Unlimited Prism Lens
- Prism Kitchen: 80 recipes with photos
- Prism Coach & Deep Insights
- Streak Shields, custom fasts
Yearly
€19.99
≈ €1.67/month · 7 days free, reminder on day 5
- Everything in Monthly
- A free week to try it all
- Family Sharing included
Lifetime
€49.99
One payment, Prism forever
- Everything in Yearly
- No renewals, ever
- All future Prism features
Euro prices include VAT. US dollar prices are before sales tax. Prices in other regions follow the App Store's local pricing. Payment goes through your Apple ID.
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Fasting isn't for everyone, and LeanFast knows that
Onboarding includes a short safety check. If you're under 18, pregnant or breastfeeding, or have a history of disordered eating, LeanFast won't create a fasting plan. It offers a gentle meal-rhythm mode instead. If you have diabetes or another condition, your plan is capped at a 12-hour overnight fast and we suggest talking to your doctor.
FAQ
Good questions
What is intermittent fasting?
You eat within a daily window, for example 8 hours, and fast for the rest, for example 16 hours. It's about when you eat rather than a strict diet. Many people find it an easier way to eat less and more mindfully.
Which program should I choose?
You don't have to decide. LeanFast looks at your experience, activity, age, BMI and goal and recommends one. You can compare all three on the plan screen and switch at any time.
Do I need an account?
No. Everything works on your device without one. An account, created with a 6-digit email code and no password, only adds backup and restore across devices.
Does Lens work in Europe?
Yes. Lens reads EU and US nutrition labels in English, French, German, Spanish, Italian, Portuguese and Dutch, and recognition runs on your device. Barcode lookups that aren't in the built-in database ask Open Food Facts for the barcode number only.
Does coffee break my fast?
Black coffee, plain tea and water are generally fine. Milk, sugar and most “diet” extras aren't. Scan them with Lens and it tells you whether they break your fast.
How does the free trial work?
The yearly plan starts with 7 free days. We remind you on day 5, and if you cancel before the trial ends you pay nothing. Manage it in your iPhone's Settings › your name › Subscriptions.
Does LeanFast work on iPad?
Yes. LeanFast works in any orientation, in Split View and in a resized window. With room to spare, Kitchen shows the recipe next to the list and Plan opens the day you're shaping next to your week. Your plan and history follow you between iPhone and iPad when you sign in.
Does LeanFast work with Apple Watch?
Yes. The Watch app shows your stage ring and lets you start and end fasts, log water and see your stages, with complications for your watch face. It keeps working when your iPhone is out of range and syncs once it's back.
Does it connect to Apple Health?
If you choose to. LeanFast can read your height, weight, steps and sleep to set up your plan and keep your weight chart current, and it saves the weight and water you log. You pick each data type in Apple's permission screen, and Health data is never used for ads or shared.
What if I feel unwell while fasting?
Tap “Not feeling well?” on the Today screen, or “I don't feel well” in Settings or on your Apple Watch. LeanFast stops your fast, shows simple recovery steps, and offers a one-tap call to your local emergency number. Your streak is protected.
Which languages does LeanFast support?
English, German, French, Spanish, Italian, Portuguese (Portugal and Brazil), Catalan and Russian. The app follows your iPhone's language and uses English for any other language.
Which iPhones are supported?
Any iPhone that runs iOS 26, and Apple Watch with watchOS 26. Advice written by Apple Intelligence needs a compatible device. On other iPhones LeanFast falls back to its built-in rules.
Your rhythm is waiting.
LeanFast is coming soon to the App Store. Questions or ideas? We'd love to hear them.