Oregon Scientific GR101
From MiOS
(Difference between revisions)
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Formulas for males and females | Formulas for males and females | ||
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| + | Z = raw_impedance / impedance_factor | ||
%water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100 | %water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100 | ||
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BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]] | BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]] | ||
| − | |||
%fat = ( 4.57 / BD - 4.142 ) x 100 [Brozek, see [3]] | %fat = ( 4.57 / BD - 4.142 ) x 100 [Brozek, see [3]] | ||
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Formulas for females | Formulas for females | ||
| − | FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt | + | FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt [Tanita Corporation, see [2]] |
| − | + | ||
%fat = ( Wt - FFM ) / Wt x 100 | %fat = ( Wt - FFM ) / Wt x 100 | ||
Revision as of 17:59, 30 September 2012
Product information:
Manual:
http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf
Research:
Hacking the GR101 revisited (see [0]) or:
How to convert the raw impedance reading from a GR101 to percentage body fat and percentage body water - by Ap15e
Definitions:
raw_impedance: data from RFXtrx
BD : Body Density [kg/m^3]
FFM : Fat Free Mass [kg]
Wt : Weight [kg]
Ht : Height [cm]
Z : Impedance [ohm]
%fat : percentage body fat [%]
%water : percentage body water [%]
Constants (best fit to formulas for data from a spreadsheet publicly available, see [1])
impedance_factor = 39.198
hydration = 0.728895
Formulas for males and females
Z = raw_impedance / impedance_factor
%water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100
Formulas for males
BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]]
%fat = ( 4.57 / BD - 4.142 ) x 100 [Brozek, see [3]]
Additional formulas for percent body fat:
%fat = ( 4.95 / BD - 4.5 ) x 100 [Siri, see [3]]
%fat = ( 4.374 / BD - 3.928 ) x 100 [Schutte; for African-Americans, see [3]]
%fat = ( 4.86 / BD – 4.39 ) x 100 [Wagner]
Formulas for females
FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt [Tanita Corporation, see [2]]
%fat = ( Wt - FFM ) / Wt x 100
Notes
The formulas for males (Brozek) match the values on the remote display to a high degree
(error is < 0.5% for %fat and < 0.3% for %water for the data from the spreadsheet).
The formulas for females yield higher errors. There is insufficient data in the spreadsheet
for further analysis.
References
[0] http://www.fabienletort.com/blog/2008/domotic-help-us-hack-the-gr101.html
[1] http://spreadsheets.google.com/ccc?key=pQy-b-0ho4QdU4ecNy0TLLg&hl=fr
[2] Jebb SA, Cole TJ, Doman D, Murgatroyd PR, Prentice AM.
Evaluation of the novel Tanita body-fat analyser to measure body composition by comparison with a four-compartment model.
Br J Nutr. 2000 Feb;83(2):115-22.
PMID:10743490
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10743490
Full text: http://journals.cambridge.org/abstract_S0007114500000155
NOTE: The unit of measure for the height in the formula for body density is cm, not m.
[3] The Process of Physical Fitness Standards Development
Full text: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA495349
Requirements:
tbc
Downloads:
tba
Installation:
tbd
Further reading:
tbc
