Measurement of Body Composition in the Elderly: Dual Energy X-Ray Absorptiometry, Underwater Weighing, Bioelectrical Impedance Analysis, and Anthropometry

Abstract

Body composition of both younger and older subjects was estimated using several different methods in order to evaluate their use with elderly subjects. Estimates were obtained by dual energy x-ray absorptiometry, underwater weighing, bioelectrical impedance analysis, and skinfold measurement in 48 younger subjects (26–40 years) and 44 older subjects (65–85 years). In older men and women the underwater weighing percent fat estimates were significantly higher than all other methods. Bone mineral explained a significant proportion of the variance in the difference between the dual energy x-ray absorptiometry and underwater weighing estimates of percent fat (R² = 0.442-0.627). Because of its insensitivity to variability in bone mineral, we recommend that the underwater weighing method be not used to estimate percent fat in older men and women. Dual energy x-ray absorptiometry provides an alternative which accounts for the age-related decrease in bone mineral density.

Dual energy X-ray absorptiometry body composition and aging in a population-based older cohort

“…20, 21 In fact, DXA has been suggested as a better method for assessing body composition than underwater weighing in older adults, because it is able to account for age-related decreases in bone mineral density. 22 There are some limitations to this study. We were unable to partition-measurement error in our body composition measures because repeat measurements were not made to test reliability.…”

Assessment of Body Composition in Elderly: Accuracy of Bioelectrical Impedance Analysis

“…The underwater weighing method is currently considered to be the 'gold standard' for body composition assessment. Therefore, as recently demonstrated [32], this method -based upon a bicompartmental model where the fat-free component of the body is assumed as constant -is not recommended in the elderly, because of its insensitivity to variability in bone mineral characteristic of aging. This method led to an overestimation of FM and consequently to an underestimation of FFM.…”

Improved nutrient intake in older obese adults undergoing a structured diet and exercise intentional weight loss program

“…This scanner detects the energy that has passed through the body and a computer analyzes the differential attenuation to calculate body fat. DXA offers high precision, intra-test reproducibility and low radiation and has been validated against hydrodensitometry (6,12).…”