Add a weight
Tap the + button at the bottom of the screen and type in your weight. You can save it to Apple Health as well. If Apple Health can't save it, the app keeps it instead.
Flex Scale & Fast
Weight and fasting, in one place
Record your weight and your fasts, and see them next to your sleep and activity from Apple Health. There's no account, and your health data stays on your iPhone.
Coming soon to the App Store for iPhone
What it does
Track your weight and fasts together
Flex Scale & Fast is an app for recording your weight and your fasts, and seeing them next to your sleep, steps and workouts. You can look back at it all in charts, a calendar map and a day-by-day timeline.
It reads from Apple Health, so readings from your iPhone, Apple Watch or smart scale show up without typing them in again. Your fasts are recorded in the app.
You don't need an account. Everything stays on your iPhone. The app doesn't use the internet, and we don't run a server for it.
Features
What you can do
Time your fasts
Choose a target of 12, 14, 16, 18, 20 or 24 hours and start. The timer works from the time you started, so closing the app doesn't lose your progress. You end the fast when you're ready.
Today at a glance
See your latest weight and how it changed over the last 7 days, your current fast, your average sleep, today's steps and your latest resting heart rate. Tap your weight to switch between kilograms and pounds.
Your weight in numbers
The Weight tab shows your latest reading, your average weekly change over the last two weeks, a 7-day moving average, and how much you've changed over 7 days, 30 days, 90 days or all time.
A chart of your trend
The Trends tab charts your readings with a 7-day average line, over 7 days, 30 days, 90 days, a year or all your history. If you've set a goal, your target range is shaded on the chart.
A calendar of your days
The daily map lays your days out week by week. Switch it between weight change, fasting hours, steps, active energy, sleep and workout minutes. Tap a day to see what was recorded.
Every day in one list
The timeline puts your weight, fasts, sleep, steps, active energy and workouts together, one row per day. You can also switch to separate lists of your fasts, the weights you added and your workouts.
Wins for steady habits
Wins mark steady progress, such as your first fast, reaching a fast target, or weighing yourself on five of the last seven days.
Set a goal, if you want one
Choose to lose, maintain or gain weight, with a target range and a weekly rate. The weekly rate stops at about 1% of your weight when losing, or 0.5% when gaining, and the app tells you why. You can use the app without a goal.
Start a new phase
Starting a new goal keeps your earlier one as a past phase. You can hide readings from before the new phase started, and show them again at any time. Nothing is deleted.
Export and import
Export your fasts, goals and the weights you added to a file, from the last month up to everything. You can include your Apple Health data too. Importing only adds what isn't already there.
Set it up your way
Choose light or dark mode, one of four accent colours, kilograms or pounds, and one of eight Home Screen icons. If you're gaining weight, you can use neutral colours so a rise doesn't look like a warning.
Devices
Made for iPhone
Flex Scale & Fast works on iPhone with iOS 18 or later. It works with Apple Health, so it can show readings from your other devices and apps.
Your iPhone
Add weights and start fasts on your iPhone. The app checks Apple Health for new readings each time you open it, or when you pull down to refresh.
Apple Watch
There's no Apple Watch app. The sleep, steps, active energy, resting heart rate and workouts your watch saves to Apple Health show up in the app.
Scales and other apps
Weights from a smart scale or another app show up too, as long as they are saved to Apple Health.
Pricing
Free to use
Flex Scale & Fast is free to download. There are no ads, no in-app purchases and no subscriptions.
Free
Everything on this page
- Weights, fasts, trends, the daily map and wins
- Goals and phases
- Export and import
- No account to create
Before you start
What you need
An iPhone
Running iOS 18 or later.
Apple Health, if you want it
Connect it to bring in your weight, sleep, steps, active energy, resting heart rate and workouts. If you skip it, you can still add weights and fasts yourself.
Nothing to sign up for
There's no account. Open the app and start.
Your fasts and the weights you add are only stored on your iPhone. They aren't in iCloud or your backups, so export them before you delete the app or change phones.
Flex Scale & Fast is for keeping track and doesn't give medical advice. If you have a health condition or take medication, talk to a doctor before you start fasting.
Flex Scale & Fast is an independent app made by Elixir Consultancy Services Ltd. It is not made, endorsed or sponsored by Apple.
Feedback
Questions or ideas?
If something doesn't work, or there's a feature you'd like, send us an email. We read every message.
The app's diagnostic log helps us find out what went wrong. In the app's Settings, tap Version ten times and turn on Record diagnostics. Try the thing that went wrong again, then tap Share this log and add it to your email. Closing the app clears the log, so share it first. The log never includes your weight or other health readings.
support@elixircs.com