LOVE!
I love this app so far! It’s super cute and helpful
Free
About
This app visualizes your body's fuel usage during workouts using a playful butter and baguette gauge. It estimates your fat-vs-carb mix based on live heart rate data and displays your heart rate zones. Designed for curiosity and motivation, it keeps all data private on your device.
✓Glanceable fuel gauge visualization
✓Estimates fat vs. carb burn
✓Live heart rate monitoring
✓Heart rate zone display
✓Private by design, no tracking
✓Medication offset feature
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What's New in Bread or Butter
1.1
August 19, 2026
Connect a Bluetooth heart-rate strap (like a Polar H10) to see your fuel mix live — on your watch or iPhone, no workout needed. The iPhone becomes a live gauge of its own when a strap is connected. Added an optional tip jar, too, if you'd like to say thanks.
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FAQ
What is Bread or Butter?
Bread or Butter is a health and fitness app that visualizes your body's estimated fat vs. carb fuel usage during workouts. It uses your live heart rate to display this information in a playful, glanceable format.
How does Bread or Butter estimate fat vs. carb burn?
The app reads your live heart rate and maps your intensity to an estimated fat/carb split using the classic "crossover" curve. It also displays your current BPM and heart-rate zone based on your heart-rate reserve.
Is Bread or Butter accurate for medical advice?
No, Bread or Butter is designed for curiosity and motivation, not medical use. The fat/carb split and heart-rate zones are ballpark, textbook estimates and should not be considered measurements or medical advice.
Does Bread or Butter have ads?
No, Bread or Butter is ad-free. The app is designed with privacy in mind, keeping all data on your Apple Watch and not tracking users.
What devices is Bread or Butter compatible with?
Bread or Butter is available for Apple Watch and iPhone. It integrates with Apple's Workout app to read live heart rate data.
How often is Bread or Butter updated?
The latest version of Bread or Butter is 1.1, which was last updated on August 19, 2026. Updates typically include improvements and new features.
Can I adjust my heart rate zones in Bread or Butter?
Yes, you can set your own heart-rate zones in Settings, or they can be read automatically from Health based on your resting heart rate and age. There is also a medication offset feature to adjust for stimulants.
What do users like about Bread or Butter?
Based on its 5.0-star rating from 1 review, users likely appreciate the playful and unique visualization of workout intensity, the privacy-focused design, and the motivational aspect of seeing their fuel gauge.