American Population Body Composition Averages from the NHANES-III Data Set
The purpose of this document is to provide the statistical averages of the body composition of average
Americans and provide reference averages with which an individual may be compared to the population
examined in NHANES-III.
The following eighteen (18) tables illustrate the average body composition of Americans. The tables
DO NOT illustrate "ideal" or "target" values. Furthermore, the tables may show values that are consid-
ered to be "unhealthy" by medical professionals. The purpose of this document is strictly limited to pro-
viding a body composition reference of the population examined in NHANES-III.
The values of Total Body Water, Fat Free Mass, Fat Mass, Body Mass Index, Basal Metabolic Rate, and
Phase angle for males and females were calculated by using the reference data as reported in NHANES-
III and applying those values to the RJL Systems equations referred to as "NHANES-III" [1,2,3].
The reference tables are split by gender into two sections of nine (9) tables each. Each table shows refer-
ence values for decade age groups. The ﬁrst table in each section reports average height and weight from
the NHANES-III data set and include the following parameters.
Table 1. NHANES Baseline
Age decade of age
n observations in each decade
Average weight Kg average weight for decade expressed in kilograms
Average weight Lb average weight for decade expressed in pounds
Average height Cm average height for decade expressed in centimeters
Average height In average height for decade expressed in inches
Following each baseline are tables for averages of:
Table 2. TBW (Total Body Water)
Table 3. ICW (Intracellular Water)
Table 4. ECW (Extracellular Water)
Table 5. FFM (Fat Free Mass)
Table 6. FM (Fat Mass)
Table 7. BMI (Body Mass Index)
Table 8. BMR (Basal Metabolic Rate)
Table 9. Phase Angle (Phase Angle)
Each table includes the following statistics in both English and Metric units:
Mean the center of the average range
Standard Deviation (Std Dev) the variance of the average range
And may also include:
Percent of weight the percentage of total weight
If you want to determine the average range for body fat, in pounds, for males in the 20-29 year age
1. Find the table named Fat Mass in the Male section.
2. Find the column labeled 20-29.
3. Find the rows labeled Mean (lb) and Std Dev (lb)
4. The mean is 42.5 lbs and the standard deviation is 20.3 lbs. Add 20.3 to 42.5 to ﬁnd the high end
of the average range and subtract 20.3 to ﬁnd the low end of the average range.
5. The average fat mass of an American male between the ages of 20 and 29 is between 22.2 and
 Shumei S Sun, W Cameron Chumlea, Steven B Heymsﬁeld, Henry C Lukaski, Dale Schoeller, Karl
Friedl, Robert J Kuczmarski, Katherine M Flegal, Clifford L Johnson, and Van S Hubbard Development
of bioelectrical impedance analysis prediction equations for body composition with the use of a multi-
component model for use in epidemiologic surveysAm J Clin Nutr 2003;77:331-40.
 WC Chumlea, SS Guo, RJ Kuczmarski, KM Flegal, CL Johnson, SB Heymsﬁeld, HC Lukaski, K
Friedl and VS Hubbard Body composition estimates from NHANES III bioelectrical impedance
data/fRInternational Journal of Obesity (2002) 26, 1596-1609
 Giuseppe Sergi, et. al. Accuracy of Bioelectrical Impedance Analysis in Estimation of Extracellular
Space in Healthy Subjects and in Fluid Retention States. Annals of Nutrition and Metabolism (1994)