Lean Mass Index (LMI)
Lean Mass Index (LMI) is total lean soft tissue mass divided by height squared (kg/m²), measured by dual-energy X-ray absorptiometry (DXA). Lean soft tissue excludes bone mineral. LMI normalises lean mass for body size, allowing comparison across people of different heights.
These percentiles are a FitnessNorms derivation from NHANES 1999-2004 DXA scans for 12,957 US adults aged 20 and over, all race and Hispanic-origin groups, using the measured DXA values and the values NCHS imputed for participants who could not be scanned; see the methodology. The NHANES scans used Hologic scanners with the Schoeller calibration; results from another DXA brand or calibration are not directly comparable.
Data source: FitnessNorms derivation from NHANES 1999-2004 DXA About this study
Reference population: US adults aged 20 and over in NHANES 1999-2004 with measured or NCHS-imputed DXA data, all race and Hispanic-origin groups
Lean Mass Index (LMI) Norms Chart by Age and Sex (kg/m²)
| Age | Sex | Percentile | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| 20-24 | Male | 14.98 | 17.01 | 18.40 | 20.24 | 23.88 |
| Female | 12.48 | 14.02 | 15.12 | 16.60 | 20.16 | |
| 25-29 | Male | 15.19 | 17.27 | 18.62 | 20.46 | 24.26 |
| Female | 12.36 | 13.99 | 15.48 | 17.45 | 20.62 | |
| 30-34 | Male | 15.51 | 17.43 | 19.00 | 20.60 | 24.03 |
| Female | 12.54 | 14.12 | 15.45 | 17.42 | 20.45 | |
| 35-39 | Male | 15.52 | 17.50 | 19.06 | 21.09 | 24.18 |
| Female | 12.83 | 14.10 | 15.44 | 17.70 | 22.05 | |
| 40-44 | Male | 15.89 | 17.94 | 19.36 | 21.15 | 24.05 |
| Female | 12.78 | 14.40 | 15.80 | 17.76 | 21.93 | |
| 45-49 | Male | 15.75 | 17.83 | 19.41 | 20.71 | 23.79 |
| Female | 12.61 | 14.14 | 15.89 | 18.05 | 21.58 | |
| 50-54 | Male | 15.64 | 17.91 | 19.39 | 20.90 | 23.85 |
| Female | 12.45 | 14.15 | 15.58 | 17.45 | 20.75 | |
| 55-59 | Male | 14.85 | 17.42 | 18.74 | 20.60 | 23.64 |
| Female | 12.46 | 14.06 | 15.78 | 17.73 | 21.53 | |
| 60-64 | Male | 15.45 | 17.66 | 19.27 | 20.73 | 23.38 |
| Female | 12.66 | 14.01 | 15.57 | 17.26 | 20.65 | |
| 65-69 | Male | 15.00 | 17.37 | 18.70 | 20.30 | 23.52 |
| Female | 12.51 | 14.16 | 15.61 | 17.24 | 20.31 | |
| 70-74 | Male | 14.94 | 16.90 | 18.26 | 19.78 | 21.97 |
| Female | 12.26 | 13.88 | 15.16 | 16.67 | 19.30 | |
| 75-79 | Male | 14.69 | 16.72 | 17.90 | 19.21 | 21.66 |
| Female | 12.45 | 13.75 | 15.04 | 16.62 | 18.98 | |
| 80-84 | Male | 14.62 | 16.08 | 17.33 | 18.48 | 20.38 |
| Female | 12.29 | 13.40 | 14.61 | 16.06 | 18.77 | |
| 85+ | Male | 13.88 | 15.23 | 16.81 | 17.84 | 20.48 |
| Female | 12.03 | 13.43 | 14.52 | 15.81 | 18.21 | |
What to expect by age group
Among US adults aged 30 to 34, the middle 50% measure 17.43 to 20.60 kg/m² for men and 14.12 to 17.42 kg/m² for women. Median LMI is highest at 45-49 (19.41 kg/m² for men, 15.89 kg/m² for women) and lowest at 85+ (16.81 and 14.52 kg/m²). Men's median is 2.29 to 3.81 kg/m² higher than women's in every age bracket.
| Age | Males | Females |
|---|---|---|
| 20-24 | 17.01 to 20.24 | 14.02 to 16.60 |
| 25-29 | 17.27 to 20.46 | 13.99 to 17.45 |
| 30-34 | 17.43 to 20.60 | 14.12 to 17.42 |
| 35-39 | 17.50 to 21.09 | 14.10 to 17.70 |
| 40-44 | 17.94 to 21.15 | 14.40 to 17.76 |
| 45-49 | 17.83 to 20.71 | 14.14 to 18.05 |
| 50-54 | 17.91 to 20.90 | 14.15 to 17.45 |
| 55-59 | 17.42 to 20.60 | 14.06 to 17.73 |
| 60-64 | 17.66 to 20.73 | 14.01 to 17.26 |
| 65-69 | 17.37 to 20.30 | 14.16 to 17.24 |
| 70-74 | 16.90 to 19.78 | 13.88 to 16.67 |
| 75-79 | 16.72 to 19.21 | 13.75 to 16.62 |
| 80-84 | 16.08 to 18.48 | 13.40 to 16.06 |
| 85+ | 15.23 to 17.84 | 13.43 to 15.81 |
Detailed Breakdowns
Select an age group and sex below for detailed percentile charts, tables, and ratings.
Frequently Asked Questions
What is Lean Mass Index?
Lean Mass Index (LMI) is total lean soft tissue mass divided by height squared (kg/m²). It is analogous to BMI but measures the lean (non-fat, non-bone) component of body mass. A higher LMI indicates more muscle and other lean tissue relative to height.
What counts as lean mass?
Lean soft tissue is everything that is not fat or bone: muscle, organs, water and connective tissue. It is dominated by skeletal muscle. These values exclude bone mineral content, as the National Center for Health Statistics does for the same scans.
Can I compare my DEXA report to these values?
Only approximately. DXA results depend on the scanner brand, software and calibration. These values come from Hologic scanners using the Schoeller calibration in NHANES 1999-2004. A GE Lunar scan, or a Hologic scan with a different calibration, can report a different lean mass for the same body, so a small difference from these percentiles may reflect the scanner rather than the body.
How does LMI differ from Appendicular Lean Mass Index (ALMI)?
LMI uses total body lean mass. ALMI uses only the arms and legs, and it is the measure the European sarcopenia consensus (EWGSOP2) defines its muscle-quantity cut-offs on.
Are these norms representative of non-US populations?
They describe US adults measured in 1999-2004. The data cannot establish how other populations compare.
How do these values relate to Kelly et al. 2009?
Kelly et al. 2009 fitted separate reference curves for non-Hispanic White, non-Hispanic Black and Mexican American adults from the same NHANES scans. This page pools all US adults, as the site's other NHANES measures do, so its values differ from any one of Kelly's curves. The method behind it reproduces the National Center for Health Statistics' own published percentiles for the same survey years; see the methodology.