Measurement of body fat in healthy elderly men: A comparison of methods

Background. Nutritional evaluation of elderly people is of great importance . Two-component methods for body composition assessment, such as anthropome try and bioelectrical impedance (BIA), are widely used in clinical practice . but their fundamental assumptions may be invalid in older people. Dual-en ergy X-ray absorptiometry (DXA) is a relatively new method for reliable and direct measurements of body mass in its three basic components: total body bone mineral content (TBBMC), mineral free lean tissue mass (LTM), and fat . In this study, percent body Fat (%BF) estimates from anthropometry and BI A in men of various ages were compared with corresponding measurements by D XA. Methods. Body fat percentage was estimated in 67 men aged 20-95 by anthropo metric measurements (skinfold thickness, body mass index, or BMI), BIA, and DXA. Age-specific equations were used for anthropometry and BIA. Limits of agreement were calculated between DXA and the other methods. Results. The equations based on BMI and BIA systematically overestimated %B F with respect to %BF measured by DXA in people of all ages. Intermethod di fference between DXA and skinfold thicknesses was less marked, but in over- 80-year-olds %BF predicted by skinfold measurements underestimated %BF meas ured by DXA. Interindividual and age-related variation in TBBMC and in Eat- free mass mineralization could partly explain the intermethod differences f ound between DXA and the other methods. Conclusions. Because of practical constraints, anthropometry and BIA are of ten the only available options for body composition assessment in clinical routine; therefore, further research on the validity and improvement of the se methods in older people is indicated.