Evaluating CMR

Indices of Total Adiposity – BIA

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Figure 2: Example of a bioelectrical impedance analysis (BIA) segmental scale also showing an individual on the scale

Figure 2: Example of a bioelectrical impedance analysis (BIA) segmental scale also showing an individual on the scale

BIA is a simple, inexpensive technique that uses the body’s ability to conduct a mild electrical current to indirectly estimate fat-free mass or percent body fat (Figure 2) (29, 30, 40). Body conductivity is proportional to total body water and fat-free mass, but can be affected by many factors such as hydration, temperature, distribution of fluid within the intra- and extra-cellular compartments, the cross-sectional area of the limbs, and body length (29, 30, 40). Depending on the model and equation, BIA has been reported to both overestimate and underestimate fat mass (41), while generally underestimating body fat in obese individuals (29). Nevertheless, it appears that BIA is a fairly accurate predictor of fat and fat-free mass (SEE = 2 to 3 kg) (29), with smaller estimate errors compared to BMI and other anthropometric measures ( 2). However, one of the major limitations of BIA is that most equations lose accuracy when they are applied to other populations that differ with regards to age, race, gender, or adiposity, and few if any equations appear useful across heterogeneous populations (29). In addition, studies are divided as to whether BIA is better than BMI in predicting traditional cardiovascular disease risk factors (43-45). 

Reference

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2. Ho SC, Chen YM, Woo JL, et al. Association between simple anthropometric indices and cardiovascular risk factors. Int J Obes Relat Metab Disord 2001; 25: 1689-97.

29. Heymsfield SB, Lohman TG, Wang Z, et al. Human Body Composition. 2005.

30. Bray GA, Bouchard C and James WPT. Handbook of Obesity. 1998.

40. Ellis KJ, Bell SJ, Chertow GM, et al. Bioelectrical impedance methods in clinical research: a follow-up to the NIH Technology Assessment Conference. Nutrition 1999; 15: 874-80.

41. Fogelholm M and van Marken Lichtenbelt W. Comparison of body composition methods: a literature analysis. Eur J Clin Nutr 1997; 51: 495-503.

43. Willett K, Jiang R, Lenart E, et al. Comparison of bioelectrical impedance and BMI in predicting obesity-related medical conditions. Obesity (Silver Spring) 2006; 14: 480-90.

44. Nagaya T, Yoshida H, Takahashi H, et al. Body mass index (weight/height2) or percentage body fat by bioelectrical impedance analysis: which variable better reflects serum lipid profile? Int J Obes Relat Metab Disord 1999; 23: 771-4.

45. Kobayashi J, Murano S, Kawamura I, et al. The relationship of percent body fat by bioelectrical impedance analysis with blood pressure, and glucose and lipid parameters. J Atheroscler Thromb 2006; 13: 221-6.

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