The body density in young and middle aged males can be estimated from body measurements using generalized equations developed by Jackson and Pollock.
Population used in study:
(1) 403 adult males, with 308 men used for the derivation set and 95 for validation
(2) ages from 18 to 61 years
(3) Subjects varied in body structure, body composition and exercise habits.
Measurements:
(1) Skinfold thicknesses were measured in mm using a Lange skinfold fat caliper.
(2) Waist and forearm circumferences were measured in meters using a Lufkin steel tape.
Sites of skinfold thickness measurement:
(1) chest
(2) axilla
(3) triceps
(4) subscapula
(5) abdomen
(6) suprailium
(7) front thigh
sum of 7 skinfolds =
= SUM(skinfold thickness from all 7 sites in mm)
sum of 3 skinfolds =
= (skinfold thickness chest in mm) + (skinfold thickness abdomen in mm) + (skinfold thickness thigh in mm)
Sum of 7 Sites
Equation 1 (R = 0.902, standard error 0.0078)
body density in g per mL =
= 1.112 - (0.00043499 * (sum of 7 skinfolds in mm)) + (0.00000055 *((sum of 7 skinfolds in mm)^2)) - (0.00028826 * (age in years))
Equation 2 (R = 0.916, standard error 0.0073)
body density in g per mL =
= 1.101 - (0.00041150 * (sum of 7 skinfolds in mm)) + (0.00000069 * ((sum of 7 skinfolds in mm)^2)) - (0.00022631 * (age in years)) - (0.0059239* (waist circumference in meters)) + (0.0190632 * (forearm circumference in meters))
Equation 3 (R = 0.893, standard error 0.0082)
body density in g per mL =
= 1.21394 - (0.03101 * (LN(sum of 7 skinfolds in mm))) - (0.00029 * (age in years))
Equation 4 (R = 0.917, standard error 0.0073)
body density in g per mL =
= 1.17615 - (0.02394 * (LN(sum of 7 skinfolds in mm))) - (0.00022 * (age in years)) - (0.0070 * (waist circumference in m)) + (0.02120 * (forearm circumference in m))
Sum of 3 Sites
Equation 5 (R = 0.905, standard error 0.0077)
body density in g per mL =
= 1.10938 - (0.0008267 * (sum of 3 skinfolds in mm)) + (0.0000016 * ((sum of 3 skinfolds in mm)^2)) - (0.0002574 * (age in years))
Equation 6 (R = 0.918, standard error 0.0072)
body density in g per mL =
= 1.0990750 - (0.0008209 * (sum of 3 skinfolds in mm)) + (0.0000026 * ((sum of 3 skinfolds in mm)^2)) - (0.0002017 * (age in years)) - (0.005675 * (waist circumference in m)) + (0.018586 * (forearm circumference in m))
Equation 7 (R = 0.888, standard error 0.0083)
body density in g per mL =
= 1.18860 - (0.03049 * (LN(sum of 3 skinfolds in mm))) - (0.00027 *(age in years))
Equation 8 (R = 0.915, standard error 0.0073)
body density in g per mL =
= 1.15737 - (0.02288 * (LN(sum of 3 skinfolds in mm))) - (0.00019 * (age in years)) - (0.0075 * (waist circumference in m)) + (0.0223 * (forearm circumference in m))
Siri Equation
percent body fat =
= (((4.95 / (body density in grams per cubic cm)) - 4.5) * 100
