Value of body fat mass vs anthropometric obesity indices in the assessment of metabolic risk factors

OBJECTIVE: To compare the value of body fat mass (%FM) to indirect measures of general (body mass index (BMI)) and central adiposity (waist circumference (WC); waist-to-height ratio (WC/ht)) for the prediction of overweight- and obesity-related metabolic risk in a study population with a high prevalence of metabolic syndrome (MSX). METHODS: BMI, WC, WC/ht, body composition (by air-displacement plethysmography) and metabolic risk factors: triglycerides, cholesterol, HDL-cholesterol (HDL-C), uric acid, systolic blood pressure (BPsys), insulin resistance by homeostasis model assessment (HOMA-IR) and C-reactive protein (CRP) were measured in 335 adults (191 women, 144 men; mean age 53 +/-13.9 years, prevalence of MSX 30%). RESULTS: When compared with BMI and WC, %FM showed weaker associations with metabolic risk factors, except for CRP and BPsys in men. In women, HDL-C and HOMA-IR showed the closest correlations with BMI. For all other risk factors, WC or WC/ht were the best predictors in both sexes. Differences in the strength of correlations between an obesity index and different risk factors exceeded the differences observed between all obesity indices within one risk factor. In stepwise multiple regression analyses, WC/ht was the main predictor of metabolic risk in both sexes combined. However, analysis of the area under receiver operating characteristic curves for prediction of the prevalence of >or=2 component traits of the MSX revealed a similar accuracy of all obesity indices. CONCLUSIONS: At the population level, measurement of body FM has no advantage over BMI and WC in the prediction of obesity-related metabolic risk. Although measures of central adiposity (WC, WC/ht) tended to show closer associations with risk factors than measures of general adiposity, the differences were small and depended on the type of risk factor and sex, suggesting an equivalent value of methods.     

Comparison of methods to estimate body fat in growth hormone deficient adults

OBJECTIVE  All of the presently used methods for in-vivo determination of body composition have inherent methodological errors and depend on various assumptions. We have therefore compared several different methods used to measure body fat in adult GH deficiency during GH treatment.
DESIGN  Comparison of body composition data from a two-phase trial with an initial placebo-controlled, double-blind 6-month period, followed by open treatment with GH until all patients had received GH for 12 months.
PATIENTS  Twenty-five patients with known GH deficiency entered the study. Baseline examinations were complete in 23 patients, and 22 patients (16 males, 6 females) completed all examinations after treatment.
MEASUREMENTS  Body fat calculated from total body potassium (TBK) by whole-body ⁴⁰K counting, total body water (TBW) by tritium dilution, total body nitrogen (TBN) by neutron activation, and bioelectric impedance (BIA) measurements were compared to body fat determinations by dual-energy X-ray absorptiometry (DEXA) in two-compartment and multicompartment body composition models.
RESULTS  At baseline, DEXA fat mass agreed well at group level with measurements based on TBW or TBK alone, in a four-compartment model based on TBK and TBW, and a multicompartment model based on bone mineral (by DEXA), TBN and TBW. Body fat by BIA agreed less well. After 12 months of GH treatment, body fat decreased by all methods used. This decrease was smaller by DEXA than by the other methods. The four-compartment model based on TBK and TBW, and TBW alone, showed the best agreement with changes in DEXA fat.
CONCLUSION  All methods showed a decrease of body fat with GH treatment, but variation between methods was considerable.     

The assessment of obesity: methods for measuring body fat and global prevalence of obesity

Fat is a normal component of the human body that is stored in adipose tissue. Obesity can be defined as a condition of excessive fat accumulation to the extent that health and well-being are affected. Body fat can be determined in vivo in different ways, using rather accurate laboratory techniques or using simple estimation techniques that can also be applied in field conditions. For population studies, the World Health Organization defines cut-off values for obesity based on the body mass index (BMI): weight/height squared (kg/m²). Generally, for adults, if the BMI exceeds 25 kg/m², a subject is considered to be overweight, and if the BMI exceeds the value of 30 kg/m², a subject is considered obese. However, the relationship between body fat percentage and BMI differs between ethnic groups, and, as a consequence, cut-off points for overweight and obesity based on BMI will have to be ethnicity specific. This means that, in some populations, the cut-off points could be lower or higher than the recommended figures. Adapting cut-off point values will have important consequences for prevalence data in some countries as the prevalence of obesity will dramatically increase or decrease. The prevalence of obesity, in children as well as in adults, is high in many countries all over the world and is rising. Given the impact of obesity on health, this is a public health issue that needs to be addressed seriously.     

Comparison of different methods to assess body composition of weight loss in obese and diabetic patients

Recombinant human epidermal growth factor (REGEN-D 150), which was cloned and over expressed in E. coli, has shown enhanced healing of chronic diabetic foot ulcers (DFU) by significantly reducing the duration of healing in addition to providing excellent quality of wound healing and reepithelization. Post-marketing surveillance (PMS) study of REGEN-D 150 in 135 patients of DFU in India was compared with Phase III clinical trial data of REGEN-D 150 in India. Statistical analysis of study data determined that the empirical survival probability distribution, in terms of non-healing of ulcers, was lowest in the case of PMS study, better than that for Phase III; more DFU patients were healed in PMS study. Percentage of patients cured in any given week (e.g., in week 10) is above 90% in PMS study, as compared to 69% in Phase III clinical trial; this percentage was around 18% for the control group with placebo in the Phase III trial. The average wound healing time was significantly lower in PMS study, 4.8 weeks, while it was 9 weeks in Phase III clinical trials while the average wound healing with REGEN-D 150 was found to be 86% in this study. REGEN-D 150 has been found to result in healthy granulation and stimulate epithelization, thus leading to final wound closure. The PMS study has established the efficacy of REGEN-D 150 in faster healing of diabetic foot ulcers.     

Comparison of the body mass index to other methods of body fat evaluation in ethnic Japanese and Caucasian adolescent girls

OBJECTIVE: The aim of this study was to assess the body mass index (BMI) and its relationship with other methods of body fat evaluation in pre- and post-menarcheal, Japanese and Caucasian female adolescents, using two different cut-off points for obesity: 28% and 30%. DESIGN: A cross-sectional study with incomplete sampling, using the subject as the evaluation unit. SUBJECTS: A total of 436 Japanese and Caucasian female adolescents in two age groups: 10-11 (pre-menarcheal adolescent); and 16-17 (post-menarcheal adolescents). METHODS: For the BMI the cut-off point for thinness was set at the 5th percentile of the BMI distribution of the NCHS reference population and the cut-off point for overweight and obesity was set at the 85th percentile. Body composition was assessed using foot-to-foot bioelectrical impedance analysis (BIA), near-infrared interactance (NIR) and Slaughter skinfold equations (SKI). The statistical comparison of the methods was performed using the kappa agreement test and the McNemar disagreement test. RESULTS: In the 10- and 11-y-old girls, the BMI was considerably and significantly correlated with the other methods. The major agreements were: in Japanese adolescents BMI x NIR=82.3% (cut-off point of 28%), BMI x BIA=85.7% (cut-off point of 30%); in Caucasian adolescents BMI x NIR=80.7% (cut-off point of 28%), BMI x BIA=87.4% (cut-off point of 30%). The disagreement above the diagonal between BMI x NIR was higher within the two groups for both the cut-off points, revealing that the girls identified as obese by the BMI were considered eutrophic by NIR. In the 16- and 17-y-old adolescents, the BMI demonstrated low or no correlation with the other methods. Furthermore, it presented disagreements below the diagonal, revealing that the BMI identified fewer obese subjects than the other methods. CONCLUSION: Among the 10- and 11-y-olds, the BMI presented a good correlation with the other methods, independent of ethnicity. The BMI can therefore be used in place of these methods, although it may underestimate obesity. Among the 16- and 17-y-olds, the BMI presented low or no agreement with the other methods, suggesting that it is probably not a suitable index for this age-group in studies focusing on the identification of obesity. In such cases the choice of one of the other methods, depending on availability, cost or technical experience, may represent a better approach.     

Body composition by three-compartment model and relative validity of some methods to assess percentage body fat in mexican healthy elderly subjects

BACKGROUND: In Mexico, there is scarce information about the body composition in the elderly. Some researchers have measured body fat by anthropometry and bioelectrical impedance. These techniques are practical and can be used in the field; however, proper validation is required. This implies the use of accurate and precise methods. In the elderly, Siri's three-compartment (3C) model has been proposed as feasible alternative to the gold standard four-compartment model. OBJECTIVE: To evaluate the body composition by the 3C model and the relative validity of densitometry and hydrometry methods to assess the percentage body fat (%BF) in 37 healthy Mexican elderly subjects. METHODS: The body density was measured by air displacement plethysmography, total body water was evaluated by means of an isotopic dilution technique, and two different hydration factors were used to determine the fat-free mass. These measurements were used to calculate %BF by the 3C model. Accuracy and precision of the methods were tested by a two-way analysis of variance and regression procedures and bias by Bland and Altman analysis. RESULTS: In men and women as a whole group, the %BF by the 3C model was 34.4 +/- 8.01. Women had higher values of %BF as compared with men (41.7 +/- 3.7 vs. 29.4 +/- 6.4; p < 0.0001). The regression procedures showed that air displacement plethysmography was accurate and precise only in women and in the whole group. Regression analyses of %BF by total body water (using both hydration factors) and 3C model showed that the intercepts were not different from zero and that the slopes were not different from 1.0 in men and women separately and as group. CONCLUSION: In this study, the total-body water method revealed a good relative validity (accuracy, precision, and freedom from bias) as compared with the 3C model in men and women both separately and as a group and may be acceptable for the estimation of %BF in individuals or groups of healthy elderly subjects.     

Glucose metabolism in obesity: influence of body fat distribution

The dose-response relationships between portal venous insulin concentrations and hepatic glucose production and between peripheral insulin concentrations and peripheral glucose utilization were determined in 8 nonobese and 17 obese premenopausal women with either upper or lower body fat localization. The glucose production dose-response curves for the two obese groups were shifted to the right at all levels of portal insulinemia. The upper body obese women had a greater rightward shift compared to the lower body obese women. The peripheral glucose utilization dose-response curve was shifted to the right in the lower body obese women, but maximal glucose utilization was normal. The upper body obese women had both a greater rightward shift and a marked reduction in maximal glucose utilization. The insulin concentrations that had half-maximal effects on glucose production and utilization were similar in each group. These results indicate that the liver is not inherently more sensitive to insulin than peripheral tissues. Obesity is associated with a moderate diminution of hepatic and peripheral insulin sensitivity. Upper body fat localization in obese women is characterized by a greater diminution in insulin sensitivity and decline in peripheral insulin responsivity than is lower body fat localization. The marked peripheral insulin resistance in the former group may account for the increased prevalence of glucose intolerance.     

Comparison of four laboratory methods to assess aspirin sensitivity.

The purpose of this study was to compare the ability of four commercial platelet function assays to detect aspirin response in normal individuals taking 81 or 325 mg aspirin in a single-dose response and then in a 7-day dosing regimen. We employed the Chronolog 570VS whole-blood aggregometer with agonists 1.0 microgram/ml collagen and 0.5 mmol/l arachidonic acid, the PFA-100 epinephrine/collagen cartridge closure time, the Accumetrics Verify/Now arachidonic acid cartridge, and the urine 11-dehydrothromboxane immunoassay normalized to urine creatinine. Fifty normal individuals who met the inclusion criteria were consented in the single-dose study. Blood and urine were collected at baseline, and then each participant was given a 81 mg enteric-coated aspirin tablet. Blood and urine were collected after 24 h. After a minimum of 14 days the process was repeated with a 325 mg aspirin dose. Forty-five individuals were enrolled in the 7-day study. Blood and urine were collected at baseline. Then each participant was given an 81 mg dose of aspirin daily for 7 days. After 7 days, blood and urine specimens were obtained and tested. After a minimum washout period of 14 days the process was repeated using a 7-day regimen of 325 mg enteric-coated aspirin tablet. Student's t-test indicated statistical significance between baseline and post responses in both dosing regimens (P < 0.05). Individuals were not consistently identified as aspirin responsive across all platforms. All assays discriminated between platelet response and nonresponse to aspirin at both dosages. It may be necessary to employ multiple assays to detect individual platelet response.     

Influence of body fat distribution during childhood on body fat distribution in adulthood: a two-decade follow-up study

Development of body fat distribution was assessed in a two-decade follow-up study. The present article describes the development of various trunk/extremity ratios and gives the figures by age and sex between 1 month to 21 years. The relationship between adult and childhood skinfold (SF) ratio measurements is weak in boys and slightly better in girls. From the present and our previous study, we can select adiposity measurements in children which both are associated to pathologies and have the best correlations with adult values, i.e. the body mass index (BMI) in both sexes, trunk SF in boys and the subscapular/arm SF ratio in girls. Consequently, a boy with both high BMI and trunk SF values or a girl with both high BMI and subscapular/arm SF values have an increased risk of centralized obesity at adult age.     

Psychosocial and socio-economic factors in women and their relationship to obesity and regional body fat distribution

BACKGROUND: Abdominal obesity, as well as psychosocial and socio-economic handicaps are risk factors for serious, prevalent diseases. Connections between these variables have been found in men. OBJECTIVE: The principal aim of the present study was to analyse the associations between psychosocial and socioeconomic factors with body mass index (BMI) and the waist-to-hip circumference ratio (WHR) in women. DESIGN: A cohort study of data derived from questionnaires. SUBJECTS: 1137 women from a population sample of 1464 women born in 1956. MEASUREMENTS: Occupational, social and leisure time conditions, smoking and alcohol habits, as well as height, weight and waist and hip circumferences. RESULTS: BMI was associated with teetotalism and negatively to wine drinking. WHR correlated directly with cigarette smoking and negatively with consumption of wine and beer. Both BMI and WHR, adjusted for each other and for smoking and alcohol, showed independent associations with low education, unemployment and problems at work when employed, as well as with little physical activity and much TV-watching. In addition, the WHR showed a negative, independent relationship to housing conditions. CONCLUSION: These observations suggest psychosocial and socio-economic handicaps as well as a low physical activity in abdominally obese women. Similar observations have been made previously in men, but only with the WHR, suggesting an influence of obesity in these relationships in women only. Another interesting gender difference is the positive relationship between being married with BMI in men, as well as being divorced and living alone with the WHR in men only.     

Relationship between anthropometric indices of body fat distribution and basal energy metabolism in healthy Maltese women

A sample taken from a population (Maltese) with a high incidence of the metabolic complications of central obesity was studied to determine: (1) whether the standard Schofield equations adequately predict the basal metabolic rate (BMR) in this population: (2) whether the Maltese have a greater tendency for central obesity compared with other populations; (3) whether the distribution of body fat influences energy expenditure and fuel selection. Healthy women responding to a public advertisement were sampled randomly from the Maltese population. Correlation analysis and analysis of variance were used to study relationships between BMR and body composition. Anthropometric parameters (including body fat distribution indices, bioimpedance) and BMR were measured after an overnight fast. Six percent of the respondents were excluded because of recent illness, instability of diet or of body weight. Fifty subjects attended a clinic at the Medical School. The distribution of excess fat between central and peripheral areas in the Maltese population was similar to that reported for the British population. The Waisthip ratio (WHR) reflected neither basal heat production (BMR) nor the contribution of fat oxidation to BMR. The Schofield equations systematically underestimated BMR by 5.4%±0.86% (P<0.05). The study suggests a limitation in using the Schofield equations for predicting BMR in the female Maltese population studied. It also suggests that the fat distribution between central and peripheral areas in this population has no effect on BMR.     

Evaluation of body fat changes during weight loss by using improved anthropometric predictive equations

BACKGROUND/AIM: Skinfold-based equations are widely used to evaluate body fat (BF), but over-/underestimation is often reported. We evaluate the capacity of improved skinfold-based equations to estimate BF changes during weight reduction and compare them against well-established equations. METHODS: Overweight adults (n = 44) participated in a 4-month weight reduction intervention. Dual-energy X-ray absorptiometry (DXA) and anthropometric measurements were taken at baseline and after intervention. The BF% was calculated using García, Peterson, and Durnin and Womersley (DW) equations. RESULTS: Baseline and postintervention BF% measured by DXA correlated highest with BF% predicted according to García (r = 0.934 and r = 0.948, respectively), followed by Peterson (r = 0.941 and r = 0.932, respectively) and DW (r = 0.557 and r = 0.402, respectively); only a slight systematic error in overestimating the BF% was observed in estimates according to García (r = 0.147 and r = 0.104, respectively; p < 0.001), while increasing errors occurred using the Peterson (r = 0.624 and r = 0.712, respectively; p < 0.001) and DW (r = 0.767 and r = 0.769, respectively; p < 0.001) equations. Moderate correlations between BF changes (kg) measured by DXA and predicted by DW (r = 0.7211), Peterson (r = 0.697), and García (r = 0.645) were observed. CONCLUSION: Improved skinfold equations cannot accurately measure changes in BF after weight reduction.     

Effect of obesity and body fat distribution on sex hormones and insulin in men

To investigate the relationship between body fat distribution, sex hormones, and hyperinsulinemia in male obesity, we examined 52 obese men (body mass index [BMI], 35.0 +/- 6.1, mean +/- SD) and 20 normal-weight controls. Their waist to hip circumference ratio (WHR), which was used as an index of fat distribution, was 0.985 +/- 0.052 and 0.913 +/- 0.061 (P less than .005), respectively. Compared with controls, obese men presented significantly lower levels of total (357 +/- 132 v 498 +/- 142 ng/dL; P less than .005) and free testosterone (14.2 +/- 2.9 v 17.1 +/- 2.6 pg/mL; P less than .05) and sex hormone-binding globulin (SHBG; 41.7 +/- 31.9 v 66.2 +/- 18.6 nmol/L; P less than .001) without any significant difference on the other sex steroid or on gonadotropin concentrations. Fasting and glucose-stimulated insulin and C-peptide levels were significantly higher in obese than in controls, and in obese with the WHR value greater than 0.97 (corresponding to the distribution median) than in those with WHR lower or equal to 0.97. BMI was negatively correlated with testosterone (P less than .005), free testosterone (P less than .01), and SHBG (P less than .001) and positively with fasting (P less than .001) and glucose-stimulated (P less than .005) C-peptide concentrations, whereas no relationship was found between these variables and WHR values. On the contrary, WHR was significantly correlated with fasting and post-glucose insulin levels (P less than .05), but not with those of sex steroids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relative validity of different methods to assess body composition in apparently healthy elderly women.

Body composition was assessed by means of densitometry, anthropometry and bioelectrical impedance in 28 healthy, elderly females, aged 67-78 years. Underwater weighing was used as the reference method. Mean body mass index (BMI) was 26.3 +/- 3.4 kg/m2. Body fat percentage from body density was 39.6 +/- 5.6%. The fat-free mass (FFM) from body density was 41.0 +/- 5.4 kg. Mean predicted FFM using different prediction formulas from the literature ranged from 38.8 +/- 4.2 to 46.3 +/- 5.3 kg. The differences between FFM from densitometry and FFM using either prediction equation were highly correlated, thus part of the difference is probably due to an error in the reference method. The different prediction equations revealed rather good relative validity, compared to the densitometric method, with the exception of equations based on skinfold measurements developed in younger reference populations. Age-specific prediction equations based on BMI and bioelectrical impedance measurement may be used to assess body composition in the elderly. Prediction equations using skinfold thickness measurements are less appropriate for this purpose.     

Accuracy of anthropometric indicators of obesity to predict cardiovascular risk

CONTEXT: Obesity is associated with various cardiovascular risk factors. The body mass index (BMI) is the standard measure of overweight and obesity. However, more recently, waist to hip ratio (WHR) or waist circumference (WC) as more sensitive measures for visceral obesity have been proposed to be more indicative of cardiovascular risk. OBJECTIVE: This study was performed to test the predictive value of anthropometric parameters for the presence of several cardiovascular risk conditions. DESIGN: The DETECT (Diabetes Cardiovascular Risk-Evaluation: Targets and Essential Data for Commitment of Treatment) study is a cross-sectional, clinical-epidemiological study. PARTICIPANTS: We studied 5377 unselected subjects (2016 men, 3361 women) without arteriosclerotic disease, aged 20-79 yr, from the DETECT laboratory sample. SETTING: This study was conducted by primary care physicians. INTERVENTION: We measured anthropometric parameters and assessed cardiovascular risk by clinical examination, patient history, and a standardized laboratory program. MAIN OUTCOME MEASURES: We assessed the associations of BMI, WC, hip circumference, WHR, and waist to height ratio (WHtR) to cardiovascular risk by calculating the area under the receiver-operating characteristic curve and adjusted odds ratios for metabolic syndrome, dyslipidemia, and type 2 diabetes. RESULTS: The area under the receiver-operating characteristic curve for WHtR was significantly higher than for all other anthropometric parameters with respect to all risk conditions in women and to dyslipidemia and type 2 diabetes in men. The odds ratios for the presence of risk conditions with 1 sd increase of each anthropometric parameter were highest for WHtR or WC. CONCLUSIONS: There are some indications that WHtR or WC may predict prevalent cardiovascular risk better than BMI or WHR, even though the differences are small.     

Validity of body mass index and waist circumference in the classification of obesity as compared to percent body fat in Chinese middle-aged women

OBJECTIVE: To evaluate the validity of currently recommended obesity cutoffs of body mass index (BMI, in kg/m(2)) and waist circumference (WC, in cm) for Asians by the WHO/IASO/IOTF and for Chinese by the Working Group on Obesity in China (WGOC) using the percentage body fat (%BF)-obesity criteria. DESIGN: A cross-sectional study. SUBJECTS: A total of 1122 community-based Hong Kong Chinese women aged between 41 and 63 years. MEASUREMENTS: Total %BF and percent truncal fat (%TF) were measured using dual-energy X-ray absorptiometry. Anthropometric indices were measured using standard methods. RESULTS: Regression analyses showed that the BMI cutoffs of 23, 24, 25, and 28 kg/m(2) corresponded to the %BF of 34.8, 35.9, 36.9 and 39.5%, and the 80 cm WC corresponded to 34% TF, respectively. Compared with the %BF obesity cutoff (>/=40%), the WHO/IASO/IOTF BMI-obesity criterion (>/=25) shows a good sensitivity (75%) and specificity (71%); and the WGOC criterion (BMI>/=28) had a low sensitivity (41%) but an excellent specificity (93%), respectively. Corresponding to the BMI cutoffs of 23, 24, 25 and 28 kg/m(2), the %BF cutoffs associated with peak kappa statistic were 33, 34, 35 and 40%, and the relevant %TF linked with 80 cm WC was 33%, respectively. CONCLUSION: BMI and WC have a good accuracy in the prediction of obesity. Our findings suggest that the WGOC BMI cutoffs are appropriate, but 80 cm of WC is a very rigorous cutoff for this population when using the criteria of 34 and 40% of body fat or truncal fat for overweight and obesity.