What is Lean Body Mass?

lean body mass-Mesomorph Body Type


Lean body mass (LBM) is the total weight of the body minus all fat weight. It includes muscle, bone, organs and bodily fluids.


  • Skeletal muscle typically comprises about half of lean body mass in healthy adults. Water weight is also a major component.
  • Women have about 10% less lean mass than men on average. But strength training reduces this gender lean mass gap.
  • Higher lean body mass increases metabolism and caloric needs since it takes more energy to sustain muscle and organ tissues.
  • DEXA scans provide the most accurate lean mass measurement. Bioelectrical impedance scales estimate LBM but have greater error.


  • Determining an athlete has 85 lbs of lean mass and 8 lbs of fat mass = 93 lbs total.
  • Gaining 5 lbs of muscle to increase lean body mass from weight training.

Related Terms

  • Fat mass, fat-free mass, muscle mass, body composition

Common Questions

  • How can I increase LBM? Follow a progressive lifting routine with sufficient protein intake.
  • Does cardio or weight training increase LBM more? Resistance training builds muscle so it has greater effects on increasing lean mass.

Do Not Confuse With

  • BMI – A screening tool that does not distinguish between lean and fat mass.
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