What Is Lean Body Mass?

What Counts as Lean Body Mass?

Lean body mass (LBM) includes muscle, bone, organs, and body water — essentially your total weight minus fat mass. Tracking LBM alongside weight gives a clearer picture of whether changes on the scale reflect fat loss, muscle gain, or both.

How LBM Is Estimated

The Boer formula estimates lean body mass from height and weight:

Men: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2

Women: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3

More precise methods like DEXA scans exist, but this formula gives a solid estimate without special equipment.

Why LBM Matters

• Sets more accurate protein targets (based on lean mass, not total weight)
• Tracks whether weight changes are fat or muscle
• Feeds into other metrics like FFMI

Frequently Asked Questions

What is lean body mass?

Lean body mass is your total body weight minus fat mass, including muscle, bone, organs, and water.

How accurate is the Boer formula?

It's a widely used estimate based on height and weight; methods like DEXA scans are more precise but require special equipment.

Why does lean body mass matter?

It's useful for setting protein targets, tracking body composition changes, and calculating metrics like FFMI.