What is lean mass index (LMI)?
Lean Mass Index (LMI), also known as Fat-Free Mass Index (FFMI), is your total lean mass divided by your height squared (Fat Mass / Height² in kg/m²). It is a measure of muscularity based on lean mass and height and is correlated with both fitness and health outcomes.
LMI normal reference values:
| Male | 18-21 kg/m² |
| Female | 15-18 kg/m² |
A higher LMI indicates more lean mass (muscle, bone, organs, and water) per pound. Athletes tend to have higher LMI, which can vary by sport. LMI values varies by gender with males having higher values than females. LMI values also tend to decrease with age.
Maintaining a healthy LMI is important for healthy aging because lean muscle mass is crucial for supporting strong bones and a healthy metabolism.