Trendline is an iPhone app that reads Apple Health. This page covers moving Garmin Index readings into Health; why Health is the right destination is its own page.
The graph is the complaint. The readings are fine.
The most durable Garmin weight-tracking complaint isn't about the scale — it's about the chart. Garmin's own forums carry a long-running thread from Index owners whose weight graph spans a fixed axis tens of kilograms wide, so months of steady change render as an almost perfectly flat line; one poster's chart ran from 57 kg to 100 kg, flattening every weigh-in into invisibility (Garmin forums). The measurements underneath are fine. The fix isn't a better axis setting — it's getting the readings into a neutral store where any app can present them. Garmin, to its credit, documents exactly how.
The path: scale → cloud → Connect app → Health
An Index scale doesn't talk to your iPhone directly. It uploads each weigh-in over Wi-Fi to the Garmin Connect cloud; the Garmin Connect iOS app then syncs from that cloud and writes to Apple Health (Garmin's Apple Health FAQ). That cloud-first design is why a reading can appear in Connect before it appears in Health — the last leg belongs to the Connect app on your phone, and it has one requirement worth knowing about below.
Two ways to switch it on — both vendor-documented
Garmin's FAQ gives two equivalent enable paths (same FAQ):
- From the Apple Health app: Summary → your profile picture → Apps and Services (under Privacy) → Connect → toggle on the categories you want shared.
- From the Garmin Connect app: More → Settings → Connect Apps → Apple Health → Connect → Allow.
One quirk from the same document: Connect won't appear in Health's app list at all if the only Garmin device on your account is an Edge cycling computer — the integration surfaces with health-data devices like an Index scale or a watch.
What transfers — and the two-week backfill
The vendor-documented types include weight, body fat percentage, and BMI, alongside Garmin's activity types (steps, workouts, heart rate and kin). And Garmin documents something almost no scale maker will put in writing: on enabling the connection, the Health app imports your past data going back up to two weeks. That is the whole backfill — two weeks, not your full Garmin history. Readings older than that stay in Garmin Connect — this page won't pretend the rest of your history migrates automatically, because the vendor doesn't claim it does.
The foreground requirement
Garmin's FAQ is unusually candid about the last leg: Garmin Connect must be open in the foreground to send data to Apple Health — when the app is closed, the transfer pauses. So a weigh-in can sit in Garmin's cloud, synced and safe, while Health shows nothing new until the next time you open Connect. If Health seems perpetually behind your scale, this is the documented reason, not a broken scale. The habit that makes it a non-issue: open Connect once after you weigh in.
The source-priority gotcha
Apple Health can hold the same measurement type from several sources, and its charts display data according to source priority — a higher-priority source can effectively hide Garmin's readings even though they were written correctly (covered in the same Garmin FAQ). If Connect says it's syncing but Health's weight chart won't show it: Health → Browse → Body Measurements → Weight → Data Sources & Access, tap Edit, and drag Connect up the priority list. The readings were there all along; Health was just electing a different witness.
One direction only
The connection pushes Garmin data into Apple Health but does not pull anything back — Garmin's FAQ states Connect doesn't read from an Apple Watch or from Apple Health. A weigh-in entered by hand in Health, or written by another scale's app, will never appear in Garmin Connect. That's fine for the strategy this site recommends: Health is the neutral store; Connect is one of its writers.
What lands where
| What Garmin Connect writes to Apple Health | What Apple Health can store | What Trendline reads from Health |
|---|---|---|
| Weight, body fat %, BMI — plus activity types (Garmin FAQ, July 2026) | Weight, body fat %, lean body mass, BMI, height, waist circumference | Weight, body fat %, lean body mass — with height as context. BMI and waist are not imported. |
When Trendline launches, it will also accept manual entries for composition values Apple Health has no type for — the Index's muscle mass and body water numbers that otherwise stay in Connect.
Try the idea
The flat-line chart that opened this page is a presentation failure, not a measurement one — and you can see the difference with your own weigh-ins right now. Paste a few weeks of readings into the free weight trend calculator: raw series on top, a deliberately slower signal underneath, axis fitted to your data instead of to a 43-kilogram guess.
Sources
- Garmin support: sharing your Garmin Connect data with Apple Health (enable paths, data types, two-week backfill, foreground requirement, one-way direction, source priority)
- Garmin forums: changing the scale of the weight graph (fixed-axis complaint thread)
Trendline is not affiliated with or endorsed by Garmin. Vendor behaviors change; everything above was verified against the linked pages on July 20, 2026, with the Garmin FAQ read in a browser on that date.