Bioelectrical Impedance Analysis
The MA801 uses Bioelectrical Impedance Analysis (BIA) to determine body composition. At
its core, BIA operates by treating the human body as an electrical conductor within an
alternating current circuit, from which the alternating current resistance and impedance is
measured.
Using a combination of existing population data and in-house research, body composition
analysis formulas can calculate results based on the Impedance, Height, Gender, Age, and
Weight of the subject. These formulas are formulated with reference to gold standard
measurements such as those listed above to confirm viability and accuracy.
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VIII. ABOUT RESULTS
BIA is non-invasive and safe for all subjects, with the exception of people who have embedded
electronic medical equipment. The accuracy of BIA can be affected by various environmental
and biological factors. For more information on recommended measurement precautions,
please refer to Chapter VI. Instructions for Operation
Total Body Water, Extracellular Water, and Intracellular Water)
Total Body Water (TBW) refers to the water contained in the tissues, blood, bones, and
elsewhere. TBW in a healthy (non-obese) adult can fluctuate by roughly 5% daily, influenced by
physiological activity and consumption of food and drink
4
. Due to larger size and muscle mass,
healthy adult men have more TBW than women (on average)
5
.
For healthy (non-obese) adults, TBW constitutes ~60% of body weight and ~73% of Fat-Free
Mass
6
. However, it is important to note that this percentage is not applicable to children -
typically, children have a higher percentage of body water than adults, and TBW levels
reportedly decrease further around middle age as part of the aging process
7
. In addition, various
diseases can affect body water percentage, including renal deficiency diabetes, cardiac failure,
and cancer
8
.Therefore, BIA estimations should be used with particular caution if subject's body
water differs significantly from the representative populations used to formulate BIA algorithms.
TBW can be divided into Intracellular Water (ICW) and Extracellular Water (ECW). ICW:ECW
proportion for healthy populations is roughly 3:2 (ECW/TBW=~0.38)
9
. The Edema Index
calculates this ratio for usage by professionals.
4. Askew EW Present Knowledge in Nutrition (7th ed) 1996, p.98-107
5. Lesser GT, Markofsky J. Body water compartments with human aging using fat-free mass as the reference standard.
1979. Am J Physiol, 236, p.R215-R220.
6. Wang ZM, Deurenberg P, Wang W, Pietrobelli A, Baumgartner RN, Heymsfield SB. Hydration of fat-free body mass:
review and critique of a classic body-composition constant. The American Journal of Clinical Nutrition. 1999. Vol.69
Issue 5, p.833-841.
7. Cameron CW, Guo SS, Zeller CM, Reo NV, Siervogel RM. Total body water for white adults 18 to 64 years of age:
The Fels Longitudinal Study. 1999. Kidney Internationalk Vol.56 Issue 1, p.244-252
8. Moore FD, Haley HB, Bering EA, Brooks L, Edelman I. Further observations on total body water. Changes of body
composition in disease. 1952. Surg Gynecol Obstet, 95, p.155-180
9. Tai R, Ohashi Y, Mizuiuri S, Aikawa A, Saki K. Association between ratio of measured extracellular volume to
expected body fluid volume and renal outcomes in patients with chronic kidney disease: a retrospective single-center
cohort study. BMC Nephrology, 2014;15:189
Values
TBW
SLM
FFM
Weight
Normal Range
Compartments
Body Composition Analysis
Intracellular Water
ICW
( L )
Extracellular Water
ECW
( L )
Protein
( kg )
Mineral
( kg )
Body Fat Mass
BFM
( kg )
37.2%
23.3%
17.1%
4.8%
17.6%
26.2
16.4
12.1
3.4
12.4
42.6
54.7
58.1
70.5
25.0 ~ 30.5
15.3 ~ 18.7
8.0 ~ 11.4
2.3 ~ 3.9
7.0 ~ 14.1