Wanda H. Howell

Why bioelectrical impedance analysis should be used for estimating adiposity.

The whole-body bioelectrical impedance analysis (BIA) approach for estimating adiposity and body fat is based on empirical relations established by many investigators. Properly used, this noninvasive body-composition assessment approach can quickly, easily, and relatively inexpensively provide accurate and reliable estimates of fat-free mass (FFM) and total body water (TBW) in healthy populations. The estimated FFM or TBW values are used to calculate absolute and relative body fat amounts. When different investigators follow the same standard BIA procedures and use the same population and criterion method, similar prediction equations and relatively small prediction errors have been reported for measurement of FFM and TBW (SEE: 1.7-3.0 for FFM and 0.23-1.5 kg for TBW). The BIA approach is most appropriate for estimating adiposity of groups in epidemiologic and field studies but has limited accuracy for estimating body composition in individuals. When used as a simple index (stature2/ resistance), BIA is more sensitive and specific for grading average adiposity in groups than some other anthropometric indexes such as the body mass index. Prediction equations based on BIA have been validated and cross-validated in children, youths, adults, and the elderly, in primarily white populations and, to a limited extent, in Asian, black, and Native American populations.

The association of energy intake bias with psychological scores of women

Objective: Assess the association between reporting bias of dietary energy intake and the behavioral and psychological profiles in women.Design: At baseline a series of questionnaires were administered to 37 women, (the Marlowe-Crowne Social Desirability Scale, Weinberger Adjustment Inventory (WAI), the Eating Disorder Inventory (EDI), the Restraint Scale and Sorensen-Stunkard’s silhouettes). Subjects received training on how to record dietary records. Subjects recorded three days of dietary records to measure energy intake (EI) during a study to determine total energy expenditure (TEE) using doubly labeled water. Reporting accuracy (RA=EI/TEE×100) was determined for each subject. Statistical analysis of the data used a mixed effects model accounting for within subject variability to determine if the psychological scores were associated with reporting accuracy.Setting and subject: Women were recruited with local advertisements in Tucson, Arizona. The women had a mean (±1 s.d.) age of 43.6±9.3 yrs, body mass index (BMI) of 28.7±8.5 kg/m2 and total body fat (%TBF) of 31.9±7.3%.Results: Age and %TBF were significantly and inversely associated with RA. Furthermore, Social Desirability was negatively associated with RA. Body dissatisfaction and associating a smaller body size than one’s own as being more healthy were also associated with a lower RA.Conclusions: These results suggest that Social Desirability and self image of body shape are associated with RA. Modifications in subject training may reduce the effect of these factors on RA.Sponsorship: This project was supported by a grant from the National Institute of Diabetes, Digestive and Kidney Diseases.

Bioimpedance Spectroscopy for Clinical Assessment of Fluid Distribution and Body Cell Mass

Body composition assessment has been used to evaluate clinical interventions in research trials, and has the potential to improve patient care in the clinical setting. Body cell mass (BCM) is an important indicator of nutrition status; however, its measurement in the clinic has been limited. BCM can be estimated by the measurement of intracellular water (ICW). The assessment of extracellular water (ECW) is also important because many clinical populations undergo alterations in fluid distribution, particularly individuals with wasting, those receiving dialysis, and obese individuals. Bioimpedance spectroscopy (BIS) is a unique bioimpedance approach that differs in underlying basis from the more readily recognized single-frequency bioelectrical impedance analysis (SF-BIA) in that it does not require the use of statistically derived, population-specific prediction equations. It has the potential advantage of not only measuring total body water (TBW), as does SF-BIA, but also offering the unique capacity to differentiate between ECW and ICW and, thus, to provide an estimate of BCM. This literature review was conducted to compare available BIS devices to multiple dilution for measuring fluid compartments or BCM in a number of populations. Variable results regarding the ability of BIS to measure absolute volumes, as well as the observation of wide limits of variation, make BIS problematic for individual assessment in the clinic, particularly in populations with abnormal fluid distribution or body geometry. BIS has been found to be more accurate for measuring changes in fluid volumes or BCM, particularly in post-surgical and human immunodeficiency virus (HIV)-infected individuals. It is certainly possible that population-specific adjustments may improve the accuracy of BIS for assessing individuals in the clinical setting; however, additional research and development is needed before the method can be accepted for routine clinical use.

Validation of the Arizona Activity Frequency Questionnaire using doubly labeled water.

PURPOSE Physical activity questionnaires (PAQs) are considered the most cost-efficient method to estimate total energy expenditure (TEE) in epidemiological studies. However, relatively few PAQs have been validated using doubly labeled water (DLW) in women or in samples with diverse ethnic backgrounds. This study was conducted to validate the Arizona Activity Frequency Questionnaire (AAFQ) for estimation of TEE and physical activity energy expenditure (PAEE) over 1 month using DLW as a reference method. METHODS Thirty-five relatively sedentary women completed the AAFQ before participating in an 8-d DLW protocol to measure TEE. TEE and PAEE were estimated from the AAFQ by calculating resting metabolic rate (RMR) using the equation of Mifflin et al. (AAFQmif), by measuring RMR using indirect calorimetry (AAFQic), and using MET conversion (AAFQmet). A predictive equation for TEE was generated. RESULTS The mean +/- SD for TEE and PAEE from DLW were 9847 +/- 2555 kJ x d(-1) and 5578 +/- 2084 kJ x d(-1), respectively. Formulas using RMR to calculate the TEE and PAEE from the AAFQ tended to underestimate TEE and PAEE, whereas those that included only weight tended to overestimate TEE and PAEE. On the basis of the Mifflin et al. equation, the AAFQ tends to underestimate PAEE by 13%. This underestimation may be explained by the low lean body mass of the sample population and by effectiveness of the METs/RMR ratio in the obese. The following predictive equation was calculated: TEE (kJ x d(-1)) = (86.0 * average total daily METs) + (2.23 * RMRmif) - 6726. When the predictive equation is used, TEE calculated from the AAFQ is highly correlated with DLW TEE (adjusted r(2) = 0.70, P < 0.001). CONCLUSION The AAFQ is an effective tool for the prediction of TEE and PAEE in epidemiological studies.

Definition of Terms, Style, and Conventions Used in A.S.P.E.N. Guidelines and Standards

The American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) is a professional society of physicians, nurses, dietitians, pharmacists, allied health professionals, and researchers. A.S.P.E.N. envisions an environment in which every patient receives safe, efficacious, and high quality patient care. A.S.P.E.N.’s mission is to improve patient care by advancing the science and practice of nutrition support therapy.

Validity of self-reported energy intake in lean and obese young women, using two nutrient databases, compared with total energy expenditure assessed by doubly labeled water

Objective: To compare self-reported total energy intake (TEI) estimated using two databases with total energy expenditure (TEE) measured by doubly labeled water in physically active lean and sedentary obese young women, and to compare reporting accuracy between the two subject groups.Design: A cross-sectional study in which dietary intakes of women trained in diet-recording procedures were analyzed using the Minnesota Nutrition Data System (NDS; versions 2.4/6A/21, 2.6/6A/23 and 2.6/8.A/23) and Nutritionist III (N3; version 7.0) software. Reporting accuracy was determined by comparison of average TEI assessed by an 8 day estimated diet record with average TEE for the same period.Results: Reported TEI differed from TEE for both groups irrespective of nutrient database (P<0.01). Measured TEE was 11.10±2.54 and 11.96±1.21 MJ for lean and obese subjects, respectively. Reported TEI, using either database, did not differ between groups. For lean women, TEI calculated by NDS was 7.66±1.73 MJ and by N3 was 8.44±1.59 MJ. Corresponding TEI for obese women were 7.46±2.17 MJ from NDS and 7.34±2.27 MJ from N3. Lean women under-reported by 23% (N3) and 30% (NDS), and obese women under-reported by 39% (N3) and 38% (NDS). Regardless of database, lean women reported higher carbohydrate intakes, and obese women reported higher total fat and individual fatty acid intakes. Higher energy intakes from mono- and polyunsaturated fatty acids were estimated by NDS than by N3 in both groups of women (P≤0.05).Conclusions: Both physically active lean and sedentary obese women under-reported TEI regardless of database, although the magnitude of under-reporting may be influenced by the database for the lean women.Sponsorship: USDA Hatch Project award (ARZT-136528-H-23-111) to LB Houtkooper and WH Howell.European Journal of Clinical Nutrition (2001) 55, 940–950

Reproducibility of DXA in Obese Women

Dual-energy X-ray absorptiometry (DXA) measurements were analyzed using two versions of software (Hologic V8.1a and V8.21) to compare the short- and long-term precisions of the measurements. Software V8.21 was designed by the manufacturer to better address magnification effects on estimations of soft tissue lean mass. Twenty weight-stable, obese postmenopausal Caucasian women aged 40-70 yr participated in the study. Total and regional body composition measurements were obtained at baseline and after 3 mo, using a fan beam Hologic QDR 4500A absorptiometer. For the estimation of precision, duplicate scans obtained on the same day for nine women were analyzed using both versions of the software. The correlations between duplicate scans ranged from 0.886 to 0.998 and were similar between software versions. The CVs for fat and lean weights and bone mineral content (BMC) were 1.2%, 1.1%, and 1.7%, respectively, for software V8.21 compared to 1.3%, 1.3%, and 2.1%, respectively, for V8.1a. Systematic differences were found between software versions with higher values for fat and lean weights for software version V8.21. The 3-mo, long-term reproducibility of body composition estimates from DXA was only slightly less than short-term reproducibility for both software versions (coefficient of variation [CV] range from 1.3% for BMC weight to 11.0% for arm fat). Software V8.21 yielded smaller percentage mean differences between scale and DXA-estimated weights (-2.4% and -7.2% at baseline and -2.9% and -7.6% at 3 mo, respectively) and higher fat and lean weights (49.12 and 47.1 kg and 49.6 and 44.6 kg, respectively) than V8.1a. Reproducibility of all variables was comparable between software versions.

Body cell mass repletion and improved quality of life in HIV-infected individuals receiving oxandrolone

BACKGROUND The aim of this study was to measure changes in body cell mass (BCM) and quality of life in HIV-infected individuals undergoing oxandrolone therapy. Previous studies on oxandrolone have neither quantified changes in BCM using criterion methods nor quality of life using an HIV-specific instrument. METHODS Twenty-five HIV-infected patients (15 with an AIDS diagnosis) on standard antiretroviral and nutrition management were studied before and an average of 18.6 weeks after the initiation of oxandrolone therapy, as prescribed by their primary care physician for the treatment of weight loss. BCM was estimated from intracellular water measured by multiple dilution. Lean soft tissue mass (LTM) was measured by dual-energy X-ray absorptiometry. Quality of life was evaluated by the Functional Assessment of HIV Infection (FAHI) questionnaire. RESULTS Significant gains in body weight (2.6 +/- 3.0 kg; p < .0001), BCM (3.6 +/- 3.0 kg; p < .0001), and LTM (3.0 +/- 2.9 kg; p < .0001) occurred over an average course of 18.6 weeks of treatment. Overall quality of life improved (p = .056) and appetite improved (p = .032), both of which were positively associated with weight gain (p = .040 and p = .022, respectively). CONCLUSIONS This is the first study involving oxandrolone therapy in HIV infection to document changes in quality of life and BCM, the metabolically active component of lean body mass that reflects nutritional status better than other more global body composition parameters. Nutritional status and quality of life can improve in HIV-infected individuals receiving a combined therapeutic approach that includes oxandrolone.

Weight loss is correlated with an improved lipoprotein profile in obese postmenopausal women

Background: Changes in plasma lipid and lipoprotein distributions that occur after menopause increase the risk of cardiovascular disease in women, especially in those who are overweight. Objective: The purpose of this study was to evaluate the impact of a nine-month weight reduction program on plasma lipids, dietary intake and abdominal fat obesity. Design: A partial crossover design was used to study a weight loss treatment consisting of Phentermine hydrochloride (Fastin®, SmithKline Beecham Pharmaceuticals, Philadelphia, PA) therapy plus a low energy diet (5040 kJ/d). Forty-seven obese, postmenopausal Caucasian women (BMI of 30–38 kg/m2) were randomized into two groups, both of which received drug and diet treatment over six months. However, Group I started the intervention program three months later than Group II. Plasma total, HDL and LDL cholesterol and triacylglycerol were measured, body composition was assessed by anthropometry and dual energy x-ray absorptiometry, and food frequency records were collected at four timepoints. Results: Over nine months, women in Group II reduced body weight (14.4%), lowered plasma concentrations of LDL cholesterol (14% to 26%) and triacylglycerol (15%) and raised plasma HDL cholesterol concentration (15%). These plasma lipid changes decreased the total cholesterol/HDL cholesterol ratio from 4.3 to 3.2. All subjects decreased abdominal fat measurements and energy and cholesterol intakes, as well as percentage of energy derived from total and saturated fat during the study. Most subjects also increased dietary fiber consumption. Conclusion: Both weight loss and diet modifications are associated with an improved plasma lipid profile in obese postmenopausal women.

Effect of a Weight-Reduction Program on Total and Regional Body Composition in Obese Postmenopausal Women

The association of body fat and its distribution with risk for chronic disease is well documented.1–4 Some complications of obesity improve with a reduction in weight.5 In premenopausal women whose weight was lowered, an analysis of fat distribution by computerized tomography (CT) scan demonstrated that a decrease in the visceral/subcutaneous (V/S) ratio and in visceral fat volume was more strongly correlated with an improvement in plasma glucose and lipid metabolism than was a decrease in body weight, BMI, total fat volume, and abdominal subcutaneous fat volume. Accurate measurement of body fat and fat distribution is essential to assess the relation of regional fat mass to risk of chronic disease.6,7 The purpose of this study was to assess the impact of a weight-reduction program on total body weight loss in postmenopausal women, using indices of total and regional body composition as measured by DXA fan beam technology.