BIA and Dealing with Obesity

Das SK, Roberts SB, Kehayias JJ, Wang J, Hsu LK, Shikora SA, Saltzman E, McCrory MA.

Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston 02111, USA.

Body composition methods were examined in 20 women [body mass index (BMI) 48.7 +/- 8.8 kg/m(2)] before and after weight loss [-44.8 +/- 14.6 (SD) kg] after gastric bypass (GBP) surgery. The reference method, a three-compartment (3C) model using body density by air displacement plethysmography and total body water (TBW) by H(2)18O dilution (3C-H(2)18O), showed a decrease in percent body fat (%BF) from 51.4 to 34.6%. Fat-free mass hydration was significantly higher than the reference value (0.738) in extreme obesity (0.756; P < 0.001) but not after weight reduction (0.747; P = 0.16). %BF by H(2)18O dilution and air displacement plethysmography differed significantly from %BF by 3C-H(2)18O in extreme obesity (P < 0.05) and 3C models using (2)H(2)O or bioelectrical impedance analysis (BIA) to determine TBW improved mean %BF estimates over most other methods at both time points. BIA results varied with the equation used, but BIA better predicted %BF than did BMI at both time points. All methods except BIA using the Segal equation were comparable to the reference method for determining changes over time. A simple 3C model utilizing air displacement plethysmography and BIA is useful for clinical evaluation in this population.

Am J Clin Nutr. 1988 Jan;47(1):7-14.

Segal KR, Van Loan M, Fitzgerald PI, Hodgdon JA, Van Itallie TB.

Division of Pediatric Cardiology, Mount Sinai School of Medicine, New York, NY 10029.

This study validated further the bioelectrical impedance analysis (BIA) method for body composition estimation. At four laboratories densitometrically-determined lean body mass (LBMd) was compared with BIA in 1567 adults (1069 men, 498 women) aged 17-62 y and with 3-56% body fat. Equations for predicting LBMd from resistance measured by BIA, height, weight, and age were obtained for the men and women. Application of each equation to the data from the other labs yielded small reductions in R values and small increases in SEEs. Some regression coefficients differed among labs but these differences were eliminated after adjustment for differences among labs in the subjects’ body fatness. All data were pooled to derive fatness-specific equations for predicting LBMd: the resulting R values ranged from 0.907 to 0.952 with SEEs of 1.97-3.03 kg. These results confirm the validity of BIA and indicate that the precision of predicting LBM from impedance can be enhanced by sex- and fatness-specific equations.

J Am Acad Nurse Pract. 2007 May;19(5):235-41.

Comment in:

J Am Acad Nurse Pract. 2007 Oct;19(10):499; discussion 499.

Ricciardi R, Talbot LA.

Walter Reed Army Medical Center, Washington, DC 20012, USA. rricciardi@usuhs.mil

PURPOSE: To present an overview of bioelectrical impedance analysis (BIA) and to familiarize nurse practitioners (NPs) with the potential benefits of using BIA in prevention, monitoring, and long-term follow-up of healthy individuals and those with chronic conditions (e.g., obesity). DATA SOURCES: Original research articles and comprehensive review articles identified through Medline, CINAHL, OVID, and electrical engineering databases. CONCLUSIONS: Obtaining serial measurements of percent body fat using BIA can identify patients at greatest health risk and gives NPs an additional tool to assess treatment response in patients seeking to lose or maintain body weight and/or increase muscle mass. IMPLICATIONS FOR PRACTICE: Traditionally, height/weight tables and body mass index have been used to assess body composition and diagnose overweight and obesity. More recently, BIA has emerged as a portable and simple-to-operate instrument to evaluate body composition in the clinical setting.

Obesity (Silver Spring). 2006 Mar;14(3):415-22.

Newton RL Jr, Alfonso A, York-Crowe E, Walden H, White MA, Ryan D, Williamson DA.

Pennington Biomedical Research Center, Louisiana State University, 6400 Perkins Road, Baton Rouge, LA 70808, USA. NewtonRL@pbrc.edu

OBJECTIVE: To compare the accuracy of percentage body fat (%BF) estimates between bioelectrical impedance analysis (BIA) and DXA in obese African-American women. RESEARCH METHODS AND PROCEDURES: Fifty-five obese African-American women (mean age, 45 years; mean BMI, 38; mean %BF, 48%) were studied. BF was assessed by both BIA (RJL Systems BIA 101Q; RJL Systems, Clinton Township, MI) and DXA (Hologic QDR-2000 Bone Densitometer; Hologic Inc., Bedford, MA). Generalized and ethnicity- and obese-specific equations were used to calculate %BF from the BIA. Bland-Altman analyses were used to compare the agreement between the BIA and the DXA, with the DXA serving as the criterion measure. RESULTS: Two of the generalized equations provided consistent estimates across the weight range in comparison with the DXA estimates, whereas most of the other equations increasingly underestimated %BF as BF increased. One of the generalized and one of the ethnicity-specific equations had mean differences that were not significantly different from the DXA value. DISCUSSION: The findings show that the Lukaski equation provided the most precise and accurate estimates of %BF in comparison with the QDR 2000 and provide preliminary support for the use of this equation for obese African-American women.

Am J Clin Nutr. 1999 Jul;70(1):5-12.

Evans EM, Saunders MJ, Spano MA, Arngrimsson SA, Lewis RD, Cureton KJ.

Departments of Exercise Science and Foods and Nutrition, The University of Georgia, Athens, USA. eevans@imgate.wustl.edu

BACKGROUND: Most methods available to clinicians for estimating body-composition changes have been validated against estimates from densitometry, based on a 2-component (fat mass and fat-free mass) model. OBJECTIVE: Estimates of changes in percentage body fat (%BF) from dual-energy X-ray absorptiometry (DXA), skinfold thicknesses (SFTs), bioelectrical impedance analysis (BIA), and body mass index (BMI; in kg/m2) were compared with estimates from a 4-component (fat, water, mineral, and protein) model (%BFd,w,m), a more accurate method. DESIGN: Determinations of body density from hydrostatic weighing, body water from deuterium dilution, bone mineral and %BF from whole-body DXA, resistance from BIA, and anthropometric measures were made in 27 obese women (BMI: 31.1 +/- 4.9) assigned to 1 of 3 groups: control (C; n = 9), diet only (DO; n = 9), or diet plus aerobic exercise (DE; n = 9). RESULTS: After the 16-wk intervention, changes in body mass (BM) averaged 0.5 +/- 2.0, -7.2 +/- 7.4, and -4.0 +/- 3.3 kg and changes in %BFd,w,m averaged 2.1 +/- 1.0%, -1.2 +/- 1.4%, and -2.4 +/- 1.6% in the C, DO, and DE groups, respectively. Compared with changes in %BFd,w,m, the errors (SD of bias) for estimates of changes in %BF by DXA, BIA, SFTs, and BMI were similar (range: +/-2.0-2.4% of BM). BIA, SFTs, and BMI provided unbiased estimates of decreases in %BFd,w,m, but DXA overestimated decreases in %BF in the DO and DE groups. CONCLUSIONS: DXA, BIA, SFTs, and BMI are comparably accurate for evaluating body-composition changes induced by diet and exercise interventions; however, small changes in %BF may not be accurately detected by these clinical methods.

Obes Surg. 2005 Feb;15(2):183-6.

Metcalf B, Rabkin RA, Rabkin JM, Metcalf LJ, Lehman-Becker LB.

Pacific Laparoscopy, San Francisco, CA, USA. barbara@paclap.com

BACKGROUND: Sudden weight loss following bariatric operations for morbid obesity, such as the duodenal switch (DS), can result in a concurrent decrease in lean body mass. Several methods for tracking body composition, such as bioelectrical impedance analysis (BIA), are available to monitor these changes. One method to offset the negative effects of sudden weight loss on body mass composition may be exercise. METHODS: 100 patients who had undergone the DS operation for morbid obesity were classified as exercisers and non-exercisers based on self-reporting. Their body mass compositions were measured using BIA preoperatively and at 0.75, 1.5, 3, 6, 9, 12, and 18 months postoperatively. RESULTS: At no study interval did postoperative percent changes in weight loss differ between the exercise and non-exercise groups. At 18 months postoperatively, the exercise group showed a 28% higher loss of fat mass and an 8% higher gain in lean body mass than the non-exercise group. CONCLUSION: Exercise positively influences body mass composition following the DS. BIA can be successfully employed to monitor changes, diagnose deficiencies, and formulate treatment recommendations.

Acta Diabetol. 2003 Oct;40 Suppl 1:S139-41.

Marra M, Pasanisi F, Scalfi L, Colicchio P, Chelucci M, Contaldo F.

Department of Clinical and Experimental Medicine Medical School, Federico II University, Via Sergio Pansini 5, I-80131, Naples, Italy. marra@unina.it

To evaluate whether bioimpedance analysis (BIA) is a useful tool for predicting basal metabolic rate (BMR), sex, age, height, weight, BMI, and single-frequency BIA variables (resistance index and phase angle) were assessed in 61 young adult non-diabetic obese patients (BMI >35 kg/m(2)). BMR was measured by indirect calorimetry. In both sexes BMR significantly correlated with weight, BMI, and resistance index. Using multiple regression analysis, the following prediction equations were derived: (1). considering individual characteristics: BMR (kcal/day)=780+11.4xweight (+221 for men); (2). including also BIA variables: BMR=- 96+8.4xresistance index+8.3xweight+82.5xphase angle. Thus, in young adult, severely obese individuals, BIA variables are significant predictors of BMR.

These papers and abstracts of papers have been published in peer-reviewed journals. They may draw conclusions and discuss applications of Bioelectrical Impedance Analysis which have not been reviewed by the FDA. Statements made within them are the sole responsibility of the authors. Unless otherwise indicated, no material support was provided to the authors or study investigators by RJL Systems.