1.  A single bioelectrical impedance analysis (BIA) equation was validated for the prediction of fat mass (FM) against dual energy X-ray absorptiometry (DXA) in Indian adults  The BIA equation can be used in populations with large variations in age and body mass Inter University Research Convention-Avishkar 2011-12 Estimation of body fat mass from bioelectrical impedance analysis in Indian adults : a comparison with dual energy X-ray absorptiometry Category: 5 Engineering & Technology Level : Teacher pursuing Ph.D. Abstract  To develop a simple, inexpensive and non-invasive method for measurement of body fat mass  To develop a low cost, simple, reliable, safe and indigenous multi-frequency BIA instrument for the assessment of FM and to evaluate its performance against the DXA Objectrive What is body fat percentage?  Body fat percentage is the amount of body fat tissue as a percentage of total body weight. It consists of essential body fat and storage body fat.  The average acceptable body fate percentages are 18- 24% for men and 25-31% for women. Why body fat measurement is required? Higher percentage of fat…. Higher Health Risk  Obesity (excess fat) is a serious health problem that reduces life expectancy by increasing one’s risk developing coronary artery disease, hypertension, type II diabetes, obstructive pulmonary disease, osteoarthritis & certain types of cancers.  Too little body fat also poses a health risk because the body needs a certain amount of body fat for normal physiological functions.  Hence measurement of body fat is very important for maintaining one’s fitness level for a long and a healthy life. Measurement techniques:  Dual Energy X-ray Absorptiometry (DXA formerly DEXA)  Multicompartment Models  Anthropometric Methods What is Bioelectrical Impedance Analysis (BIA)? A small alternating current (below 1 mA) of constant magnitude and high frequency (~ 50 kHz) is introduced in to the body (or body segment) and voltage drop is measured across it. From voltage and current values body parameters such as Impedance, reactance and phase angle are calculated Whole Body Approach-BIA Segmental Body Approach-BIA Measurement of segmental BIA Parameters InBody720 Segmental Multifrequency Bioelectrical Impedance Instrument Introduction Study Group: 113 Subjects (28 men and 85 women) in the age group of 23 to 81 years The physical parameters were recorded [Weight (w), stature (h), gender, BMI and age] The segmental parameters at 5, 50 and 250 kHz frequencies were measured by InBody720 Simple regressions were calculated to test correlations between fat mass obtained from DXA and BIA parameters. With the help of SPSS package version 17, stepwise multiple regression analysis was carried out to derive BIA prediction equation for Fat Mass. In addition to the regression techniques error analysis was performed Fat Mass of each subject was measured by dual energy X-ray absorptiometry (Lunar Prodigy, DPX IQ) at Nanavati Hospital, Mumbai 1. age (year) 2. h (m) 3. BMI (Kgm -2 ) 4. w (Kg) 5. sex (M=1; F=0) From segmental parameters the total body bioelectrical parameters like (Z body ), (X body ), (Φ body ) and (R body ) are derived at 5, 50 and 250 kHz frequencies. By combining both physical and bioelectrical parameters the new parameters (Bio- physical) are formed Bioelectrical impedance analysis prediction equation for fat mass FM = 15.45 + (0.0074 X (R body250 )) – (3.89 X (sex) ; men = 1, women = 0) + (0.844 X w) – (6938 X (h 2 / Z body50 )) – (22.22 X h) + (3 X ((X body250 – X body5 )/age)) + (1.53 X(Φ body5 )) – (0.126 X (X body50 /h)) FM predicted with DXA = 28.11 ± 9.30 kg. FM predicted with BIA equation = 28.12 ± 9.11 kg (R = 0.9794, adjusted R 2 = 0.9561, SEE = 1.95 kg, TE = 1.87 kg). Paired t-test for FM by DXA Vs BIA predicted FM for subjects with age above 60 years (n = 35) Mean ± SD FM (kg) by DXA 28.9222 ± 10.1149 BIA predicted FM(Kg) 28.6267 ± 9.8814 Difference (FM by DXA- BIA predicted FM) (Kg) 0.2955 ± 1.5354 95% confidence interval for mean difference: (-4.48, 5.07) t-test of mean difference = 0 (Vs not = 0); t-value = 0.12; P- value = 0.902; DF = 67 Paired t-test for FM by DXA Vs BIA predicted FM for subjects with BMI above 27 kgm -2 (n = 44) Mean ± SD FM (kg) by DXA 36.5356 ± 7.6410 BIA predicted FM(Kg) 36.4505 ± 7.5671 Difference (FM by DXA- BIA predicted FM) (Kg) 0.0851 ± 1.9586 95% confidence interval for mean difference: (-3.14, 3.31) t-test of mean difference = 0 (Vs not = 0); t-value = 0.05; P- value = 0.958; DF = 85 Methods Table : Significant variables in bioelectrical impedance analysis model Standardized coefficient (beta) t-valuep Collinearity statistics ToleranceVIF (R body250 )0.1631.8870.0620.05318.940 (sex)-0.181-4.6570.0000.2583.871 w1.21232.6150.0000.2843.522 (h 2 / Z body50 )-0.327-2.8050.0060.02934.587 h-0.191-3.0280.0030.09810.190 (X body250 – X body5 )/age)0.1063.1940.0020.3562.808 (Φ body5 )0.0772.0180.0460.2713.696 ( X body50 /h )-0.169-3.6560.0000.1845.429 (a) Correlations of fat mass (FM) in all subjects measured by DXA and predicted by BIA equation. (b) Differences of FM in all subjects determined by using BIA and DXA. Results (a) (b) B C A.Schematic block diagram of multi -frequency bioelectrical impedance measurement System B.Photograph of circuit board of BIA Instrument C.Measurement of fat mass using BIA instrument. Development of BIA Instrument Associated Research Work and Publications  A single BIA equation for the assessment of Bone Mineral Content (BMC) was developed and validated against the DXA in Indian adults with large variations in BMI and age. Further a low cost, simple, reliable, safe and indigenous multi-frequency BIA instrument has been developed for the assessment of BMC and its performance has been evaluated against the DXA. International journals 1.“Single prediction equation for bioelectrical impedance analysis in adults aged 22-59 years”, Journal of Medical Engineering and Technology, Informa Healthcare, vol. 35, no. 2, pp. 109-114, February 2011. 2.“Estimation of bone mineral content from bioelectric impedance analysis in Indian adults aged 23-81years: a comparison with dual energy X-ray absorptiometry”, International Journal of Biomedical Engineering and Technology (IJBET), vol., no.,pp.,Inderscience Publishers. References 1.Kyle U. G., Bosaeus I., De Lorenzo A. D., Deurenberg P., Elia M., Gomez J. M., Heitmann B. L., Kent-Smith L., Melchior J. C., Pirlich M., Scharfetter H., Annemie M. W. J. Schols and Pichard C. (2004) “Biomedical impedance analysis-part II: Utilization in clinical practice”, Clinical Nutrition, vol. 23, pp. 1430-1453. 2.Bland J. M., Altman D. G. (1986) “Statistical methods for assessing agreement between two methods of clinical measurement”, Lancet, vol. i, pp. 307 A