A Garmin Index S2 pairs with Garmin Connect during setup, then uploads each measurement over Wi-Fi to your Garmin Connect account, and the Garmin Connect iPhone app then writes it to Apple Health. Garmin documents weight, body fat percentage, and BMI, a two-week backfill, and one catch: Connect must be open in the foreground to send data.
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.
A long-running complaint about Garmin weight tracking is about the chart, not the scale. A locked thread on Garmin's own forums, started by Android users, collects reports of weight graphs spanning an axis tens of kilograms wide, so steady change looks almost flat; one poster's chart ran from 57 kg to 100 kg (Garmin forums). The thread is years old, and its replies disagree: one reports properly scaled graphs on iOS and another says goal weight affects the range. We cannot say what Garmin Connect's graph does today. What we can say is that getting the readings into a neutral store where any app can present them avoids the question. Garmin, to its credit, documents how.
The path: scale → cloud → Connect app → Health
The Index S2 pairs with the Garmin Connect app during setup. After setup, with an active Wi-Fi connection, it uploads each completed measurement automatically to your Garmin Connect account (Index S2 manual). The Garmin Connect iOS app then writes to Apple Health after each successful device sync (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.
How to switch it on — both steps vendor-documented
Garmin's FAQ documents the Health-side switch and a Connect-side route for people who first declined sharing (same FAQ):
- From the Apple Health app: Summary → your profile picture → Apps and Services (under Privacy) → Connect → toggle on the categories you want shared. Garmin still prints "Apps and Services"; Apple's current guide calls this screen Apps (Apple's guide), so look for either.
- From the Garmin Connect app, if you initially declined sharing: More → Settings → Connect Apps → Apple Health → Connect with Apple Health → select the items → 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, sleep and others). 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 first thing to rule out; Garmin's FAQ does not say it is the only cause. 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 (Apple's guide). The readings were there all along; Health was just electing a different witness.
Garmin Index not syncing to Apple Health? A checklist
Work down the pipeline from the scale to Health:
- Is the scale recording at all? Garmin's Index S2 manual says to verify that setup finished and the scale is connected over Wi-Fi, and to check the batteries (Index S2 manual).
- Only weight and BMI arrived? The manual says the scale records only weight and BMI when you weigh in wearing socks. Step on barefoot for body-composition readings.
- Weighing as a guest? The manual says guest readings are not stored or synced to a Garmin Connect account, so they never reach Health. Each person needs their own profile.
- Open Garmin Connect after weighing. Garmin says Connect writes to Health after each successful sync, so a reading can sit in Connect's cloud until the app runs (see the foreground requirement above).
- Re-grant the link. In Garmin Connect, go to More, then Settings, then Connect Apps, then Apple Health, then Connect with Apple Health, and allow the items you want shared (Garmin FAQ, which gives this route for people who first declined sharing).
- Arriving but not showing? That's source priority: drag Garmin Connect up in Health's Data Sources & Access list, as described above.
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, October 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. |
Trendline is available for iPhone and also accepts manual weight and body fat entries (App Store listing), so a reading that never reaches Health can still be part of your record.
Try the idea
You can check how your own weigh-ins look on a chart fitted to them right now. Paste a few weeks of readings into the free weight trend calculator: raw series on top, a deliberately slower signal underneath.
Questions people ask
How do I connect my Garmin Index scale to Apple Health?
In the Apple Health app: Summary, your profile picture, Apps and Services (Apple's current guide calls it Apps), Connect, then toggle on the categories you want. If you first declined sharing, Garmin's FAQ gives a Connect route: More, Settings, Connect Apps, Apple Health, Connect with Apple Health, Allow.
What does Garmin send to Apple Health?
The vendor-documented types include weight, body fat percentage, and BMI, alongside Garmin's activity types.
Will my old Garmin weigh-ins transfer to Apple Health?
Up to two weeks' worth. Garmin's FAQ says that on enabling the connection, the Health app imports your past data going back up to two weeks, and readings older than that stay in Garmin Connect.
Why isn't my Garmin weight showing in Apple Health?
Garmin Connect must be open in the foreground to send data to Apple Health, so open Connect once after you weigh in; Garmin's FAQ does not say this is the only cause. If Connect says it's syncing but Health's weight chart won't show it, a higher-priority source may be hiding it: in Data Sources & Access, tap Edit and drag Connect up the priority list.
Why does my Garmin scale only record weight and BMI?
Garmin's Index S2 manual says the scale records only weight and BMI when you weigh in wearing socks. Step on barefoot for body-composition readings.
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 (locked Android-era complaint thread, not current behavior)
- Apple: manage Health data on your iPhone (app permissions, source priority)
- Garmin Index S2 owner's manual (setup and Wi-Fi checks, socks, guest users)
Trendline is not affiliated with or endorsed by Garmin. Vendor behaviors change; everything above was verified against the linked pages on July 20, 2026 and re-checked on October 18, 2026, with the Garmin FAQ read in a browser on both dates.