Trendline is an iPhone app that reads Apple Health. Everything below assumes an iPhone; the destination for your readings is Apple Health, which Android does not run.
Why premium-scale owners end up on this page
Withings owners rarely arrive here because sync is broken. They arrive because of the graph. When Withings redesigned its app in 2022, a long-running thread formed on r/withings from owners who could no longer see weight, body fat, and muscle mass on one screen and found the weight chart's resolution visibly reduced — individual weigh-ins folded into a coarser line. The thread stayed active for years; the complaints are about presentation choices, not hardware. Withings also offers Withings+, a subscription ($9.95/month or $99.50/year at review time) that adds insights and services on top of the free app; the base health data remains free. Those are the facts — we'll skip guessing at motives. The practical point: if you want your Body-series readings presented differently than the Withings app presents them, the exit is Apple Health, and Withings supports that exit better than most vendors.
Turning the export on
Withings documents the path in its own support center (Exporting Withings data into Apple Health):
Open the Withings app and go to your Profile.
Tap Settings (the gear icon), then Export health data to Apple Health.
Tap through the Apple Health connection prompts, toggle on the categories you want synced, then tap Allow and Done.
Turning all relevant categories on at this step is the whole setup. (Older Withings articles describe a slightly different menu arrangement; the steps above are the vendor's current published version as of the review date.)
The one catch, in the vendor's own words
Here is the part that generates most "Withings not syncing to Apple Health" searches, and it is not a bug. Withings states that "the syncing of data to and from Apple Health is not automatic," attributing this to an iOS restriction (vendor doc). The documented ritual: open the Withings app, open Apple Health, then return to the Withings app and swipe down on the Home tab to force a refresh — and the vendor notes these steps apply each time you want the latest readings reflected. Its troubleshooting article adds that a sync can lag by a quarter-hour or so after a measurement, and walks the permission check: iPhone Settings → Apps → Health → Data Access & Devices → Withings, with write permissions enabled (Data Synchronization Issues; see also the companion troubleshooting page).
Two practical consequences, offered as our reading of the vendor's documentation rather than anything Withings promises: first, keep Background App Refresh enabled for the Withings app (iPhone Settings → Apps → Withings) so iOS permits the app to do work when it isn't on screen; second, build the habit of opening the Withings app after weigh-ins you care about. Scale-to-Withings and Withings-to-Apple-Health are separate hops: the vendor's own check for the first is your account's web dashboard, and its remedy for the second is the app-open refresh above.
What syncs — and what stays behind
Withings publishes the list of categories that can be shared with Apple Health (What is Apple Health?). For a Body-series scale, the relevant entries are weight, body fat percentage, BMI, height, and lean body mass (heart rate too, on models that measure it). Absent from the vendor's list: muscle mass as its own line, body water, bone mass, and visceral fat. For most of those, the limit is Apple's, not Withings' — Apple Health simply has no data types for body water, bone mass, or visceral fat, a boundary every scale brand hits identically. Those readings remain viewable in the Withings app only.
And the boundary no vendor states for you: readings flow from the day you enable the export, forward. Withings does not document whether past readings transfer to Apple Health when you first toggle it on — so we don't claim it. (In the reverse direction, importing into the Withings app, the vendor does describe limits on how much history moves; the export direction is simply undocumented.) If years of Withings history matter to you, check Apple Health after enabling rather than assuming.
What lands where
| What Withings writes to Apple Health | What Apple Health can store | What Trendline reads from Health |
|---|---|---|
| Weight, body fat %, BMI, height, lean body mass — per the vendor's shareable-categories list (plus heart rate and other measures from other Withings devices). Muscle mass, body water, bone mass, and visceral fat stay in the Withings app. | Weight, BMI, body fat %, lean body mass, height, waist circumference. No types exist for body water, bone mass, or visceral fat. | Weight, body fat %, and lean body mass (height as context). BMI and waist are not imported — BMI is derivable, and neither carries trend information Trendline needs. |
When Trendline launches, it will also accept manual entries — including composition values Apple Health has no type for, like body water and visceral fat — so the readings Withings can't export can still sit alongside your trend.
When sync stalls anyway
Working from the vendor's troubleshooting doc, cheapest step first: give a fresh measurement at least the fifteen-minute delay Withings itself allows for; run the open-both-apps-and-pull-down refresh described above; confirm the reading reached Withings' servers by checking your account's web dashboard; then re-verify write permissions in iPhone Settings → Apps → Health → Data Access & Devices. If the Apple Health option is missing from your profile entirely, Withings' suggestion is a device restart (vendor doc).
Try the idea
Once your weigh-ins are landing in Apple Health, the question becomes what reads them well — which is where that r/withings thread started. Paste a few weeks of measurements into the free weight trend calculator — it runs in your browser, nothing uploads — and compare your raw series against a deliberately slower signal that one salty dinner can't yank around. If the folded-average graph frustrated you, this contrast is the alternative, with the math public.
Sources
- Withings: Exporting Withings data into Apple Health
- Withings: Importing Apple Health data (documents the non-automatic sync and forced-refresh steps)
- Withings: Apple Health data synchronization issues
- Withings: I'm having an issue syncing with Apple Health
- Withings: What is Apple Health? (shareable data categories)
- r/withings: "New app update awful" (2022 redesign thread)
- Withings: Withings+ subscription page
Trendline is not affiliated with or endorsed by Withings. Vendor behaviors change; this page states what was verifiable against the sources above on July 20, 2026.