LodestarYour Fitbit records far more than the app shows you on a typical day. If you've ever wanted to dig further into your sleep, heart rate or HRV on your iPhone, here's how the pieces fit together.
Where your Fitbit data lives
Fitbit is part of Google, and Fitbit data now lives in your Google Health account. When your Fitbit syncs, the readings are stored there: steps, workouts, heart rate, sleep sessions and stages, and overnight measures like HRV, breathing rate, blood oxygen and skin temperature.
That data belongs to your account. You can see it in the Fitbit app, and you can choose to let other apps read it.
Why the Fitbit app mostly shows summaries
The Fitbit app is designed to be quick to read. It shows a daily summary for most things: last night's sleep score and stages, a resting heart rate, an HRV figure, a step count. That suits plenty of people.
What's harder to get at is the context. How does last night compare with your usual range? Which of your numbers moved together this week? What does your HRV trend look like over six months? The raw readings needed to answer those questions are there. They just aren't all laid out that way.
How other apps can read it
Third-party apps can ask for permission to read your Fitbit data from Google Health. You'll see a Google sign-in screen that lists exactly what the app wants to access, such as sleep, heart rate or activity. You choose whether to allow it, and you can remove access later from your Google account settings.
Once connected, an app can show your data differently: longer trends, comparisons with your own baseline, scores built from several signals at once. That's what most people mean when they want "more detail".
Questions to ask any app first
Health data is personal. Before you connect anything, it's worth checking:
- Is access read-only? An app that only needs to show you your data has no reason to write to or change it.
- Where is the data processed? On your phone, or uploaded to the company's servers? If it's uploaded, how long is it kept?
- Is it shared or sold? Read the privacy policy, and check the App Store privacy label, which lists what the app collects and whether it's linked to you.
- Does it ask for more than it needs? If a sleep app wants your location, ask why.
- Can you disconnect and delete? You should be able to revoke access and have any stored data removed.
- Does it explain its scores? A number you can't trace back to your data is hard to act on.
Also remember that no consumer wearable app is a medical device unless it says so clearly. Use them to spot patterns, and take anything that worries you to a doctor.
Getting more from the data
Whatever you use, the most useful habit is comparing yourself with yourself. An HRV of 35 means very little on its own. An HRV of 35 when your usual is 50 means a lot. Our guides to your Fitbit HRV and recovery scores explain how to read those comparisons.
How Lodestar does it
Lodestar is an iPhone app built for this. It reads your Fitbit data from Google Health with read-only access, including minute-by-minute heart rate, HRV, resting heart rate, breathing rate, blood oxygen, skin temperature, sleep stages and naps, steps, workouts and calories. Every score is worked out on your iPhone. Your health data never goes to a Lodestar server, so nothing is sent to us.
It gives you daily Sleep, Recovery, Effort, Stress and Energy scores, each against your own baseline, with a breakdown of what moved each one and a Methodology screen that explains every formula. There's also a Vitals screen, Trends from a week to a year, and home-screen widgets. It's free in beta through TestFlight, and the core scores are free.