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My LBMI is missing

What to do when your LBMI is not showing up in the app

Updated over 2 months ago

Why your LBMI isn't showing up

LBMI (Lean Body Mass Index) needs body composition data from Apple Health. If it's not appearing in reThrive, one of these is usually the cause:

No body composition data in Apple Health

You haven't recorded weight and body fat percentage, or lean body mass measurements.

Permissions not granted

reThrive doesn't have permission to read your body measurements from Apple Health.

Missing height

LBMI requires your height to calculate the index, and it's not set in Apple Health.

Data is too fresh

You have entered measurements in the current week. True Age and Pace of Aging are calculated based on the 28 days historical data since last Sunday. Add readings in the preceding weeks for True Age to show.

Data is too old

You have measurements, but they're not recent enough for high confidence. True Age confidence depends on how recent your LBMI reading is:

  • High confidence: Reading less than 1 week old

  • Medium confidence: Reading 1-2 weeks old

  • Low confidence: Reading 2-4 weeks old

  • No True Age: Reading more than 4 weeks old

What LBMI needs

To calculate LBMI, reThrive needs:

Option A (preferred): Lean Body Mass

  • Direct measurement of your muscle and organ mass

  • Provided by some smart scales (Withings, Garmin, etc.)

Option B: Weight + Body Fat Percentage

  • reThrive can calculate lean body mass from these two values

  • More common, supported by most smart scales

Plus: Height

  • Required for both options

  • Usually entered once during setup

Check what's missing

Open the reThrive app and look at your Home screen:

If you see "Connect" for LBMI:

  • You're missing body composition data entirely

  • Follow the steps below to add it

If you see LBMI with some data but gaps:

  • You have measurements but they may not be recent enough

  • For high confidence, keep measurements within the past week

  • Older measurements (up to 4 weeks) will still work but show lower confidence

How to fix missing LBMI

Step 1: Add body composition data to Apple Health

You have three options:

Option 1: Use a smart scale (recommended)

If you have a smart scale that syncs to Apple Health:

  1. Make sure the scale's companion app is installed

  2. Check that Apple Health sync is enabled in the scale's app

  3. Step on the scale to record a measurement

  4. Open Apple Health and verify the data appears

Option 2: Manual entry

If you don't have a smart scale:

  1. Open the Apple Health app

  2. Tap Browse at the bottom

  3. Tap Body Measurements

  4. Choose either:

    • Lean Body Mass (if you know it from a DEXA scan or InBody test)

    • Weight and Body Fat Percentage (from any scale or measurement)

  5. Tap Add Data and enter your measurement

  6. Make sure the date is within the past week

Option 3: Add height if missing

If you haven't set your height:

  1. Open Apple Health

  2. Tap Browse > Body Measurements > Height

  3. Tap Add Data and enter your height

Step 2: Grant permissions to reThrive

Make sure reThrive can read the data:

  1. Open Apple Health

  2. Tap your profile picture (top right)

  3. Tap Apps under Privacy

  4. Select reThrive

  5. Make sure these are toggled on:

    • Lean Body Mass (if you're using option A)

    • Weight (if you're using option B)

    • Body Fat Percentage (if you're using option B)

    • Height

Step 3: Resync reThrive

Force reThrive to check for new data:

  1. Open reThrive

  2. Tap Settings (top left)

  3. Tap Apple Health

  4. Tap Sync now

  5. Wait a few seconds for the sync to complete

  6. Return to the Home screen

Step 4: Verify LBMI appears

Check your Home screen:

  • LBMI should now show a value

  • The This Week card should show LBMI with a purple marker on the day you recorded data

  • If you have all four biomarkers for the week, your True Age will update

Common issues

I added the data but LBMI still shows as missing

  • Make sure you granted permissions in Apple Health (Step 2)

  • Check that your measurement date is within the past 4 weeks

  • Try force-quitting reThrive and reopening it

  • Trigger another manual sync from Settings > Apple Health

I have a smart scale but it's not syncing to Apple Health

  • Open your scale's companion app and check for Apple Health integration settings

  • Some scales require you to enable sync in their app settings

  • Make sure the scale app has permission to write to Apple Health

  • Try recording a new measurement after enabling sync

My scale provides weight but not body fat percentage

  • Basic scales only measure weight, not body composition

  • You'll need either:

    • A smart scale with bioelectrical impedance (measures body fat)

    • Manual body fat measurements from another source

    • A DEXA scan or InBody test for lean body mass

I only have lean body mass, not weight and body fat

That's fine! Lean Body Mass is actually the preferred input. Just make sure:

  • You've entered your height in Apple Health

  • You've granted permission for reThrive to read Lean Body Mass

  • The measurement is within the past 4 weeks (more recent = higher confidence)

  • The measurement is recent (within the past week)## What happens after you fix it

Once LBMI data is available:

  • True Age will recalculate if you have all four biomarkers

  • LBMI trends will appear in your metrics over time

  • Your confidence level improves when measurements are more recent

For best results, weigh yourself consistently:

  • Same time of day (morning is best)

  • Same conditions (after waking, before eating)

  • At least once per week for high confidence

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