Support
Check here first for help with the app.
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- Open the app on iPhone and enter age, sex, weight and HRmax
- Set your target zone (fat-burning zone) and alert sensitivity
- Launch the app on Apple Watch and tap Start
- Heart rate shows in real time; you get haptic, sound and on-screen alerts when you exceed the threshold
- Tap Stop to save the workout to HealthKit
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To read heart rate in real time, judge the fat-burning zone, and save workouts. You can change permission any time from Health → Sources, or Settings → Privacy & Security → Health.
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Common estimates:
- Simple:
220 − age - Tanaka formula (often more accurate):
208 − 0.7 × age
Use a measured value if you have one. The app's numbers are guidance, not medical advice.
- Simple:
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- Is Apple Watch fitted snugly on your wrist?
- Are notifications allowed for the app in Settings?
- Is Focus / Do Not Disturb active?
- Does your sensitivity (threshold + duration) match your effort?
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- iPhone: iOS 17+
- Apple Watch: watchOS 10+
- iPhone & Apple Watch must be paired
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This app is not a medical device. Do not use for diagnosis, treatment or prevention. Consult a doctor before exercise if you have cardiac concerns.
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If the answers above don't resolve your issue:
- Email: contact@lft-farm.com
- GitHub Issues: https://github.com/lft-farm/fat-burn-watch/issues
Still need help?
If the answers above didn't resolve it, please use our contact form.