The best apps to track fat vs muscle loss
Losing weight fast, on a cut or a GLP-1? These are the ways to find out what you’re losing.
Short answer
To track whether you’re losing fat or muscle, ProgressLens is the simplest everyday option: its AI report compares your waist with your arms and shoulders, reads your matched photos and flags possible muscle loss, on iPhone and Android. MeThreeSixty and ZOZOFIT estimate lean mass or measurements from 3D scans; smart scales estimate it with bioimpedance; a DEXA scan is the reference.
Disclosure: we make ProgressLens. Details about other apps come from their own store listings and websites as of November 2026; prices and features change, so check the listing before you pay. We name each app’s weaknesses and our own.
Quick comparison
| Option | How it judges fat vs muscle | Platforms | Price |
|---|---|---|---|
| ProgressLens | Waist vs arms and shoulders, weekly rate, photo read | iPhone, Android | $39.99/year |
| MeThreeSixty | 3D avatar, lean mass estimate | iPhone, Android | Subscription |
| ZOZOFIT | 3D scan measurements | iPhone, some Android | Free plan; Premium |
| Smart scale (BIA) | Electrical impedance | Scale + app | Scale cost |
| DEXA scan | X-ray body composition | Clinic | Per scan |
The apps
1. ProgressLens
- iPhone, iPad, Android
- AI Progress Report
- Free download, Pro in-app
- 11 languages
- No account
Best for: a regular, private fat vs muscle check without extra hardware.
The muscle-loss signal is built for cuts and GLP-1 medication: it uses measurements you already take with a tape, plus your photos.
Good
- AI Analyze: body-fat range, what changed, fat vs muscle, cut or bulk verdict
- Reads photos and tape measurements together, so estimates stay consistent
- Same app and AI on iPhone and Android, in 11 languages
- No account; photos stay on your phone, analyzed photos aren’t stored or used for training
- Ghost overlay of your last photo, six measurements with charts
Watch out
- No calorie, workout or dose tracking
- No video timelapse export (use our free web tool)
- No Apple Health or Health Connect sync
- No app-specific passcode (use your phone’s lock)
2. MeThreeSixty
- iPhone, Android
- Subscription
Best for: a 3D view plus dose logging.
Builds a 3D avatar from front and side photos with body fat and lean mass estimates, and logs GLP-1 doses, per its listing.
Good
- Lean mass estimate
- Dose log
Watch out
- Scan pose can be strict
3. ZOZOFIT
- iPhone, some Android
- Free plan + Premium
Best for: scan-based measurements.
A 3D body scanner with circumference measurements and a GLP-1 log.
Good
- 16 measurements
Watch out
- Device limits on Android
4. A smart scale
- Hardware
Best for: daily trends in steady conditions.
Bioimpedance scales estimate muscle and fat mass every morning.
Good
- Automatic
Watch out
- Swings with hydration
5. A DEXA scan
- Clinic
Best for: a baseline and a check every few months.
The reference method for fat and lean mass.
Good
- Most accurate
Watch out
- Cost, a visit each time
Which should you pick?
- Weekly, private, no hardware: ProgressLens.
- 3D lean mass estimates: MeThreeSixty.
- A reference reading: DEXA.
FAQ
Frequently asked questions
Can it tell if I’m losing muscle on Ozempic, Wegovy or Mounjaro?
It gives you a muscle-loss signal. If your arms and shoulders shrink as fast as your waist while your weight drops quickly, the report flags it and suggests what to do. It’s an early warning from your photos and tape measurements, not a medical test, so talk to your clinician too.
How much muscle do people lose on GLP-1 drugs?
In trial substudies with DXA scans, roughly 25–40% of weight lost was lean mass, which includes water and organs as well as muscle.
Sources
- App Store and Google Play listings and developer websites for each app, accessed November 2026
- ProgressLens, What lifters ask about body fat, November 2026