The fat free mass in adults over 60 years of age may be overestimated if equations are used that were developed in younger adults. This reflects the changes in bone, water distribution and muscle that occur as people age.
Population studied: Adults from 60 - 83 years of age, with 35 healthy men and 37 healthy women
Method for measuring body impedance:
(1) The body impedance was measured using a body composition analyzer (type BIA 101, RJL Systems).
(2) Patient preparation: at least 2 hours after the last meal, with the bladder emptied and in the supine position.
Equation 1
fat free mass in kilograms =
= (0.360 * (10^4) * ((height in meters)^2) / (resistance in ohms)) + (0.359 * (body weight in kilograms)) + (4.5 * (gender value)) - (20 * (thigh circumference in meters)) + 7.0
Equation 2
fat free mass in kilograms =
= (0.671 * (10^4) * ((height in meters)^2) / (resistance in ohms)) + (3.1 * (gender value)) + 3.9
where:
• The gender value = 0 if female, 1 if male.
• Thigh circumference is measured just below the gluteal fold.
