Free physician-built tool

Body Composition Results Interpreter

Got two DXA, InBody, or smart-scale reports? Enter the numbers to see how much of your weight change was fat and how much was lean mass, and whether the change is bigger than the device's normal error.

Lean mass is not the same as muscle. It also includes water, stored carbohydrate, and organs. This tool shows what your reports can and can't tell you.

What measured your body composition?

Both reports should come from the same type of device. Comparing different devices isn't reliable.

Units

First report

Second report

For both measurements, was this true?

Common questions

Is lean mass the same as muscle?

No. Lean mass is everything that isn't fat or (on DXA) bone: muscle, but also water, stored carbohydrate (glycogen), organs, and skin. When you start eating less, glycogen and the water stored with it drop quickly, so early lean mass losses often overstate true muscle loss.

How accurate are smart scales?

Home smart scales estimate body composition by sending a small current through your feet, then applying an equation. Hydration, meals, and time of day can shift the result by several pounds. They can show a long-term direction, but a change of a few pounds of muscle on a smart scale isn't reliable.

How often should I get a DXA scan?

For most people, every 3 to 6 months is enough. Shorter gaps make it hard to see real change through the scan's normal error. Use the same machine and the same conditions each time.

How much lean mass loss is normal on a GLP-1?

In GLP-1 trials that used DXA, roughly a quarter to two fifths of the weight people lost was lean mass. Diets without medication show a similar range. Strength training and adequate protein are the best-supported ways to reduce it.