Trendline is an iPhone app that reads Apple Health. This page covers getting readings from these three apps into Health; why Health is the right destination at all is its own page.
If your scale's manual points at Yolanda, Feelfit, or FITINDEX — or your scale is a FitIndex, a generic "QN-Scale", a Hutbit, or an orphaned ABYON — you're in the same software family, and everything below applies.
Which scales use these apps
The family resemblance is inspectable. Yolanda is sold on the App Store by Shenzhen QingNiu Software (Yolanda listing). Feelfit and FITINDEX appear under different seller names on their App Store pages — Global eFit and PANATRADE respectively — but their Android builds ship under the package names com.qingniu.feelfit and com.qingniu.fitindex (Feelfit on Google Play, FITINDEX on Google Play), and their listings describe Apple Health sync in near-identical sentences. Three storefronts, one Qingniu lineage. Which app is whose:
- Yolanda — the maker's own-name app, paired with generic hardware that broadcasts as "QN-Scale"; owners of unbranded scales meet that name when pairing (openScale project: QN-Scale support).
- Feelfit — paired with Hutbit-branded scales — and, more importantly now, the community-documented refuge for ABYON owners whose own app vanished (Apple Support Communities; more below).
- FITINDEX — the app for FitIndex-branded scales, the best-known storefront of the three.
What each writes to Apple Health
All three listings commit to HealthKit sync, checked live on July 20, 2026:
- Yolanda and FITINDEX use nearly the same sentence: weight, body-fat percentage, fat weight, height, BMI, and resting calorie consumption "will be synchronized to HealthKit" (Yolanda listing, FITINDEX listing). Note the fine print does the sorting for you: Apple Health has types for weight, body fat %, BMI, and height from that list; "fat weight" and calorie figures land in their own corners of Health or not at all — Health has no dedicated "fat weight" body type.
- Feelfit phrases it around the weigh-in: measure with the connected scale and the relevant data "supports synchronization with HealthKit" (Feelfit listing). Each app asks about HealthKit at login or registration.
None of the three documents transferring past readings into Health. Treat sync as flowing forward from the day you enable it; history already inside the app is not documented to make the trip.
The FITINDEX chart complaint — and the fix you already own
The most persistent FITINDEX review theme isn't about the sync; it's about the in-app trend chart. From 2023 through 2026, reviewers on the listing keep describing the same behavior: the chart spaces readings evenly no matter how much time passed between them, so a reading taken after a two-month gap sits next to yesterday's as if it were the next morning, and a month of change can look identical to a year of it. One reviewer notes a developer reply from a year earlier promising a look at the interval problem, still unfixed at the time of their review (review themes on the listing, checked July 20, 2026).
We won't editorialize beyond what's observable: a chart whose x-axis ignores real dates can't show a rate of change. But this is exactly the situation Apple Health already solves — Health plots every reading on a true time axis, day, week, month, and year (Apple's guide). Once your weigh-ins sync, the honest chart is one app away, and any Health-reading app can offer a more careful one still.
ABYON owners: the Feelfit route
ABYON's own app disappeared from the App Store — owners discovered it gone around the end of 2024 — and the community thread that formed around the loss settled on Feelfit as the working alternative: multiple owners confirm their ABYON scales pair with it, and gain Apple Health sync in the process (Apple Support Communities). Two honest caveats from the same thread: Feelfit does not import the history trapped in the dead ABYON app, and readings start fresh from the day you pair. If that's you, the fuller story — what's recoverable and what isn't — is on our orphaned-scale page.
How to turn the sync on
- In the app: each of the three asks about HealthKit when you log in or register, per its listing — accept, and grant the iOS permission sheet for the data types you want written.
- If you declined earlier: Settings → Health → Data Access & Devices → the app's name, and turn write access on; or in the Health app under your profile picture → Apps (Apple's security guide).
- Then verify: take a weigh-in with the app open and check Health → Browse → Body Measurements → Weight. A 2021 FITINDEX review reports sync silently not happening — thirty seconds of checking beats a month of missing measurements. If sync won't behave, re-toggle the Health permission, and remember the fallback: a manual Health entry has the same standing as a synced one.
Readings already written to Apple Health stay there regardless of what any of these apps does next — that's the property that makes the whole exercise worth it.
What lands where
| What these apps writes to Apple Health | What Apple Health can store | What Trendline reads from Health |
|---|---|---|
| Yolanda & FITINDEX: weight, body fat %, BMI, height per their listings. Feelfit: weigh-in data, weight-centric, per its listing (all three checked 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 the composition values Apple Health has no type for — the water, muscle, and visceral-fat numbers these apps keep to themselves.
Try the idea
The complaint driving those FITINDEX reviews is really a complaint about honest time. See the difference with your own data: paste a few weeks of weigh-ins into the free weight trend calculator — it runs in your browser, nothing uploads — and look at the raw series on a real axis next to a deliberately slower signal. Day-to-day bounce is variation; the slower line is the direction.
Sources
- Yolanda on the App Store (seller: Shenzhen QingNiu Software; HealthKit description)
- Feelfit on the App Store (HealthKit description)
- FITINDEX on the App Store (HealthKit description, chart review themes)
- Feelfit on Google Play (com.qingniu.feelfit package)
- FITINDEX on Google Play (com.qingniu.fitindex package)
- openScale project: QN-Scale support (Yolanda hardware)
- Apple Support Communities: ABYON app gone; Feelfit pairing confirmed
- Apple: protecting access to Health data (Data Access & Devices)
- Apple: view your health data on iPhone
Trendline is not affiliated with or endorsed by Shenzhen Qingniu, Yolanda, Feelfit, FITINDEX, ABYON, or any scale brand named on this page. Vendor behaviors change; everything above was verified against the linked pages on July 20, 2026.