---
title: Health data
description: Weight, body composition, resting heart rate, HRV, sleep — what a cheap Android-compatible tracker and scale actually measure.
section: body
tags: [body, metrics, index]
genre: index
lastUpdated: 2026-04-20
url: https://fardiniqbal.com/docs/body/metrics
---


Everything a device or a scale says about me — weight, body composition, resting heart rate, sleep stages, stress, steps. The numeric side of Body.

Nothing here yet because the device isn't bought. The current plan is cheap, Android-native, zero subscription:

* **Xiaomi Smart Band 9** for sleep, heart rate, stress, steps (\~$40).
* **Xiaomi Mi Body Composition Scale 2** for weight, body fat, muscle mass, water (\~$30).
* **Mi Fitness** (the official Xiaomi Android app) writes both into Android Health Connect.
* **Health Data Export** (Android app, \~$5 one-time) reads Health Connect and POSTs daily JSON to this site's `/api/ingest/health` endpoint.
* The endpoint writes `src/data/metrics.ts` and commits it. Git becomes the time-series database. The page you're reading right now renders from that file.

Absolute sensor accuracy isn't the goal — trends are. A cheap tracker that gives me the same number to within the same error-bar every day tells me everything I need to know about where my sleep, weight, and recovery are *going*.

The architecture is intentional: the wearable is a swappable component. Android Health Connect sits in the middle. Swap the band or the scale next year without rewriting the pipeline.

## What this page will render when wired [#what-this-page-will-render-when-wired]

* Current weight + 7-day moving average
* Body fat % trend (30-day)
* Sleep duration sparkline (last 30 nights)
* Resting heart rate drift
* Stress / recovery score (Mi Fitness derives this from HRV-adjacent signals)

No dashboards of 40 metrics. Just the handful that move.