01
Sync Apple Health
Connect once. Every reading from your smart scale flows in automatically - and anything you enter writes back, so your data stays yours.
Leaner
Body fat % tracker
Read the trend,
not the noise.
When you're training, what matters is body composition - not the number that jumps three points overnight. Leaner smooths your daily body-fat readings into one clean trend, so you can see real progress without obsessing over the scale.
Works with any smart scale or caliper app via Apple Health.
The number that
won't sit still
A bio-impedance scale can swing 2–4 percentage points overnight from hydration, food, and skin temperature - far more than the real weekly change you're chasing. So people give up, sure it isn't working. It usually is. You just couldn't see it.
Raw readings vs smoothed trend
Daily reading
Your true trend
How it works
Three steps, then it runs itself
02
Find the trend
A double-exponential model (Holt's method) tracks both your level and direction, recovering your true body fat % today - without the lag of a plain average.
03
See real progress
Watch the trend fall, get an honest projection of when you'll hit goal, and bank milestones and streaks along the way.
Features
Single-purpose, on purpose
No calorie logging. No macros. No weight-loss guilt. Every screen is built around one metric: your body fat trend.
Smoothed trend
Raw dots stay visible, but the bold trend line is always the hero. Scrub any day to inspect it.
Honest projection
A clearly-labelled estimate of when you'll reach goal at your current rate - with the uncertainty shown, not hidden.
Journal & milestones
Every reading in one timeline, with milestones - new lows, ranges crossed, streaks - surfaced on the day you earned them.
Apple Health native
Reads from and writes back to Health, so it works with any scale you own and never traps your data.
The core idea
Trend over readings
The headline number you see each day isn't your latest reading - it's Leaner's best estimate of your true current body fat %. It moves a little each day and almost never jumps, which is exactly what makes progress legible.
- Tracks direction, so it doesn't lag behind like a 7-day average
- Absorbs a bad reading slowly instead of overreacting to it
- Four methods to choose from - simple averages to advanced Holt
today's smoothed estimate
18.4%
Each day, Leaner blends your newest reading with everything it already knew - weighting the direction you’re heading, not just today’s number. So the trend barely moves day to day, and real progress shows through the noise.
Your data stays yours
Everything lives on your device and in your own Apple Health store. No third-party analytics ever touch your health values, and nothing is sold or shared. Leaner is just a clearer lens on data you already own.
✦ LEANER PLUS
Go deeper than the trend
The trend, your number, and Apple Health sync stay free - forever. Plus adds the power tools for people serious about a cut or recomp.
Advanced smoothing
All four methods plus manual α / β tuning of the Holt model.
Full Journal & milestones
Complete history, streaks and celebrations on the day you earn them.
Multiple goals & bands
Staged targets, maintenance bands and sex-aware category insights.
Home & Lock Screen widgets
Your smoothed trend, always a glance away - no app needed.
Weekly Insights
A calm Sunday recap of your rate, projection shift and any outliers.
Start free. Upgrade to Leaner+ any time, right inside the app - 14-day free trial, cancel anytime, no ads, ever.