Are BMI and other anthropometric measures appropriate as indices for obesity? A study in an Asian population

Multiparametric body composition analysis and anthropometric empirical indicator: obesity based south Indian perspective

BACKGROUND

Obesity has emerged to be a global threat to mankind. Many abnormalities such as cardiovascular diseases and diabetes emerge as outcomes of obesity.

OBJECTIVES

The present study aimed at bringing out a technique which considers the combinational measurement of all essential anthropometric circumferences and body mass index (BMI), so that the accurate assessment of obesity can be made. To date, BMI has been considered to be the main adiposity index, but the distribution of body fat was not taken into account by BMI. The contradictory outcomes by BMI pertaining to risk factor detection in various ethnicities and populations were witnessed. Also, BMI failed to gauge obesity in muscular body builders who possess small waists and large torsos.

MATERIALS AND METHODS

The study adopted a cross-sectional design and 107 subjects from urban south India participated. The measurements of body composition and anthropometry were shown.

RESULTS

The higher significant difference of ≤ 0.001 was observed in male and female studied population, when AEI (BIA1), AEI (EXTERNAL) and BMI were compared against BFM (measured by both the devices BIA1 and BIA2).

CONCLUSIONS

The results exhibited the prominence of AEI (Anthropometric Empirical Indicator, which is the combinational measurement of all essential anthropometric circumferences and BMI) over BMI. Also, the validity of the effective functioning of low-cost, portable, simple protocol based body composition analyzer on par with the highercost, standard body composition analyzer was demonstrated by the present study.

Detecting body fat-A weighty problem BMI versus subcutaneous fat patterns in athletes and non-athletes

We aimed to describe the relationship between BMI and the subcutaneous adipose tissue topography within young athletes and non-athletic controls, to comparatively evaluate the diagnostic powers of subcutaneous adipose tissue thicknesses at different body sites, furthermore to explore appropriate cut-offs to discriminate between athletes and controls. Measurements were determined in 64 males and 42 females, who were subsequently separated into two even groups (athletes and non-athletes). The optical device LIPOMETER was applied at standardised body sites to measure the thickness of subcutaneous adipose tissue layers. To calculate the power of the different body sites and the BMI to discriminate between athletes and non-athletes, receiver operating characteristic curve analysis was performed. In men, the neck (optimal cut-off value 2.3 mm) and trunk (optimal cut-off value 15.5 mm) provided the strongest discrimination power: with 90.6% (58 of 64) of the subjects being correctly classified into athletes or non-athletes. Discrimination power of the BMI values was 64.1% (41 of 64 were correctly classified). In women, the upper back (optimal cut-off value 3.3 mm) and arms (optimal cut-off value 15.9 mm) provided the strongest discrimination power with 88.1% (37 of 42 being correctly classified). When using BMI to discriminate between athletes and non-athletes only 52.4% (22 of 42) were correctly classified. These results suggest that compared to BMI levels, subcutaneous fat patterns are a more accurate way of discriminating between athletes and non-athletes. In particular the neck and the trunk compartment in men and the upper back and arms compartment in women, were the best sites to discriminate between young athletes and non-athletes on the basis of their fat patterns.

Implication of high-body-fat percentage on cardiometabolic risk in middle-aged, healthy, normal-weight adults

OBJECTIVE

This study investigated the number of Korean adults who had a normal body mass index (BMI) but high body-fat percentage (BF%) and determined their increased risk factors for cardiovascular diseases, including high blood pressure, hyperglycemia, and dyslipidemia.

DESIGN AND METHODS

This cross-sectional study was based on 12,386 subjects (6,534 men and 5,852 women), with a normal BMI, between 30 and 49 years of age. Subjects were categorized into two groups by BF% (normal BF% group, BF% <25 for men, and BF% <30 for women; high BF(%) group, BF% ≥25 for men, and BF% ≥30 for women).

RESULTS

The proportion of subjects with a normal BMI and high BF% was 12.7% (n = 1,572; 291 [4.5%] men and 1,281 [21.9%] women). Subjects with a high BF% had a significantly higher prevalence of high blood pressure (men only), hyperglycemia, and dyslipidemia. Multiple logistic regression analyses revealed that subjects with a normal BMI and high BF% had a 1.63 (adjusted odds ratio, 95% confidence interval: 1.21-2.19) in men and 1.56 (adjusted odds ratio, 95% confidence interval: 1.36-1.80) in women increased risk of one or more cardiovascular risk factors compared to subjects in the normal BMI and normal BF% group, even after adjusting for abdominal obesity.

CONCLUSION

High BF% is associated with a high cardiometabolic risks, regardless of abdominal obesity, in normal-weight Korean adults. Thus, follow-up screening of those with a high BF% may be necessary to detect and prevent cardiometabolic diseases, particularly for women with a normal BMI.

Population differences in the relationship between height, weight, and adiposity: an application of Burton's model

The study of human variation in adiposity and lean mass is important for understanding core processes in human evolution, and is increasingly a public health concern as the "obesity epidemic" expands globally. The dominant measure of population differences in adiposity is Body Mass Index (BMI), which suffers from systematic biases across populations due to variation in the relationship between true body fat, height and weight. Here we develop simplified corrections for such anthropometric-based measures of adiposity that can take into account this population variation. These corrections derive from a recent model proposed by Burton that assumes humans accrue mass in two ways-growth in height that adds bone and muscle, and growth in body fat and the ancillary fat-free mass (FFM) needed to support this additional body fat. We analyze two ethnically diverse datasets with dual X-ray absorptiometry-measured (DXA) fat mass, assessing the fit of Burton's model and deriving novel corrections based on estimated musculoskeletal slenderness. The resulting model provides excellent fit to fat mass within populations (average R2 = 0.92 for women and R2 = 0.83 for men). World populations differ dramatically in musculoskeletal slenderness (up to a difference of 4.4 kg/m2), as do men and women (differences of 3.3-4.5 kg/m2), leading to clear population corrections. These findings point to a conceptually straightforward tool for estimating true differences in adiposity across populations, and suggest an alternative to BMI that provides a more accurate and theoretically based estimate of body fat than that traditionally derived from height and weight measures.

Differences in obesity measures and selected comorbidities in former National Football League professional athletes

OBJECTIVE

To assess the accuracy of body mass index (BMI) as a measure of obesity compared with percent body fat (%BF) directly measured by dual energy x-ray absorptiometry among retired football players.

METHODS

The level of agreement between BMI and %BF as measures of obesity was assessed by sensitivity, specificity, and the kappa statistic among 129 retired football players. Logistic regression was used to investigate the association between obesity and selected comorbidities.

RESULTS

Using BMI 30 kg/m or higher to identify obesity had poor specificity (0.36): 87 of 129 subjects were classified as obese, yet only 13 were truly obese based on %BF. Although BMI did not reliably indicate true %BF-obesity, BMI-obesity was significantly correlated with lineman position (P < 0.0001), years played (P = 0.03), and obstructive sleep apnea (P = 0.0005).

CONCLUSIONS

Percent body fat measured by dual energy x-ray absorptiometry provides a more accurate measure of obesity than does BMI among retired football players.

Cut-off points of waist circumference and body mass index for detecting diabetes, hypercholesterolemia and hypertension according to National Non-Communicable Disease Risk Factors Surveillance in Iran

INTRODUCTION

The cut-off points of waist circumference and body mass index (BMI) are varied according to different races. There is a dearth of information on these indices especially in Iranian adults. We sought to estimate the cut-off points of waist circumference and BMI for detecting diabetes, hypercholesterolemia, and hypertension.

MATERIAL AND METHODS

The data were gathered by the First Iranian Non-Communicable Disease Survey in 2005. In total, 70,981 participants between 25 and 64 years of old were selected via random multistage cluster sampling. Receiver operating characteristic curves were used to show the cut-off points of waist circumference and BMI for detecting diabetes, hypercholesterolemia, and hypertension. The maximum value the sum of sensitivity and specificity indicated the cut-off point.

RESULTS

The cut-off points of waist circumference according to maximum sum of sensitivity and specificity for detecting hypertension, diabetes, and hypercholesterolemia in men were 89.7 cm, 89.4 cm and 88.2 cm and in women were 93.9 cm, 96.2 cm and 90 cm respectively. The cut-off points of BMI according to maximum sum of sensitivity and specificity for detecting hypertension, diabetes, and hypercholesterolemia in men were 25.7 kg/m(2), 24.8 kg/m(2) and 24 kg/m(2) and in women were 26.9 kg/m(2), 26.3 kg/m(2) and 26.1 kg/m(2) respectively.

CONCLUSIONS

This was a population-based study on a huge sample on the basis of a national survey. The Iranian BMI was different from the values suggested by the WHO. The waist circumference in Iranian women was higher than that in men.

Can weight-related health risk be more accurately assessed by BMI, or by gender specific calculations of Percentage Body Fatness?

The problem of obesity over the last 10 years has consistently been referred to as a 'global epidemic'. The Body Mass Index (BMI) is the currently accepted measure for classifying weight-related risk, but is a crude measure that has not changed in 150 years. It is recognised as having significant limitations, largely due to its lack of distinction between fat and muscle tissue. As the health risks of obesity are linked to the fat content of the body, a more accurate method of classifying would be Percentage Body Fatness (PBF). Although skinfold thickness analysis is recognised as a valid and accurate estimate of PBF in field studies, this method is not routinely used in clinical practice. Using data collected from young adults in the United Kingdom, we compared classifications (underweight, normal weight, overweight and obese) using BMI, with classifications using estimated PBF (from skinfold thickness analysis). We identified disparity between these two methods in approximately 1/3 of participants. BMI correctly classified 66.5% of females and 62.7% of males, with different gender profiles of incorrect classification. Regression analysis was conducted using estimated PBF (by skinfold thickness analysis) as the dependent variable, with explanatory variables of age, height, weight, systolic blood pressure, frequency of vigorous exercise and grip strength. The resulting gender-specific formulae derived from this regression analysis provides a regression R(2) of around 65%, and improved correct classifications to 74% for females and 76% for males. This represents an average improvement of roughly ten percentage points over BMI (male: 7.2% points; female: 13.4% points). We hypothesise that the presented formulae provide gender-specific calculations of PBF, which result in a more accurate indicator of weight-related health risk, compared with BMI in this population. This provides a new approach to an increasingly important clinical issue. These formulae use data that can be easily, quickly and cost-effectively measured in a practice setting. If shown to be repeatable with larger and more diverse populations, the PBF formulae could provide an alternative to the BMI as the major indicator of body-composition related health risk. This would ensure resources are targeted more appropriately and efficiently.

Obesity epidemic: overview, pathophysiology, and the intensive care unit conundrum

Obesity is one of the leading causes of preventable death in the United States, second only to smoking. The annual number of deaths attributed to obesity is estimated to be as high as 400,000. Nearly 70% of the adult U.S. population is overweight or obese. The historical viewpoint toward obesity has deemed it to be a lifestyle choice or characterological flaw. However, given the emerging research into the development of obesity and its related complications, our perspective is changing. It is now clear that obesity is a heterogeneous disease with many different subtypes, which involves an interplay between genetic and environmental factors. The current epidemic of obesity is the result of an obesogenic environment (which includes energy-dense foods and a lack of physical activity) in individuals who have a genetic susceptibility for developing obesity. The pathophysiology associated with weight gain is much more complex than originally thought. The heterogeneous nature of the disease makes the development of treatment strategies for obesity difficult. Obesity in general is associated with increased all-cause mortality and cause-specific mortality (from cardiovascular, diabetic, hepatic, and neoplastic causes). Yet despite increased overall mortality rates, current evidence suggests that when these same patients are admitted to the intensive care unit (ICU), the obesity provides some protection against mortality. At present, there is no clear explanation for this obesity conundrum in critical illness.

The variations of body mass index and body fat in adult Thai people across the age spectrum measured by bioelectrical impedance analysis

Background

The measurements of body mass index (BMI) and percentage of body fat are used in many clinical situations. However, special tools are required to measure body fat. Many formulas are proposed for estimation but these use constant coefficients of age. Age spectrum might affect the predicted value of the body composition due to body component alterations, and the coefficient of age for body fat prediction might produce inconsistent results. The objective of this study was to identify variations of BMI and body fat across the age spectrum as well as compare results between BMI predicted body fat and bioelectrical impedance results on age.

Methods

Healthy volunteers were recruited for this study. Body fat was measured by bioelectrical impedance. The age spectrum was divided into three groups (younger: 18–39.9; middle: 40–59.9; and older: ≥60 years). Comparison of body composition covariates including fat mass (FM), fat free mass (FFM), percentage FM (PFM), percentage FFM (PFFM), FM index (FMI) and FFM index (FFMI) in each weight status and age spectrum were analyzed. Multivariable linear regression coefficients were calculated. Coefficient alterations among age groups were tested to confirm the effect of the age spectrum on body composition covariates. Measured PFM and calculated PFM from previous formulas were compared in each quarter of the age spectrum.

Results

A total of 2324 volunteers were included in this study. The overall body composition and weight status, average body weight, height, BMI, FM, FFM, and its derivatives were significantly different among age groups. The coefficient of age altered the PFM differently between younger, middle, and older groups (0.07; P = 0.02 vs 0.13; P < 0.01 vs 0.26; P < 0.01; respectively). All coefficients of age alterations in all FM- and FFM-derived variables between each age spectrum were tested, demonstrating a significant difference between the younger (<60 years) and older (≥60 years) age groups, except the PFFM to BMI ratio (difference of PFM and FMI [95% confidence interval]: 17.8 [12.8–22.8], P < 0.01; and 4.58 [3.4–5.8], P < 0.01; respectively). The comparison between measured PFM and calculated PFM demonstrated a significant difference with increments of age.

Conclusion

The relationship between body FM and BMI varies on the age spectrum. A calculated formula in older people might be distorted with the utilization of constant coefficients.

Optimal cutoffs of percentage body fat for predicting obesity-related cardiovascular disease risk factors in Korean adults

BACKGROUND

Obesity is a major health problem. It is associated with cardiovascular disease. The diagnosis of obesity is crucial to treating and preventing obesity-related medical problems.

OBJECTIVE

The objective was to determine optimal percentage body fat cutoffs in Korean adults for predicting obesity-related cardiovascular disease risk factors.

DESIGN

We evaluated the body composition and prevalence of obesity-related cardiovascular risk factors, such as hypertension, diabetes mellitus, and dyslipidemia, in 41,088 Korean adults aged 18-92 y. The optimal percentage body fat cutoffs for Korean adults were determined. Multivariable-adjusted odds ratios (ORs) of overweight and obesity were estimated by logistic regression.

RESULTS

The first cutoffs in men and women were 17% and 32% body fat, respectively; the second cutoffs were 21% and 37% body fat, respectively. The percentages of obese men and women were 41.8% and 15.9%, respectively. The adjusted OR of at least one risk factor for overweight or obesity in men was 2.22 (95% CI: 2.07, 2.38) or 4.05 (95% CI: 3.78, 4.33). The adjusted OR for women was 1.95 (95% CI: 1.79, 2.07; P < 0.0001) or 3.21 (95% CI: 2.87, 3.57).

CONCLUSIONS

Only one-fourth of Korean men had a normal body composition, whereas most of the Korean women had a normal body composition. We conclude that susceptibility to cardiovascular disease and its risk factors is higher in Korean men than in Korean women. The cutoffs are useful for providing adequate guidelines for treating and preventing cardiovascular disease. This was the first study to determine cutoffs of percentage body fat for Korean adults.

Body mass index classification misses subjects with increased cardiometabolic risk factors related to elevated adiposity

CONTEXT

Body mass index (BMI) is widely used as a measure of overweight and obesity, but underestimates the prevalence of both conditions, defined as an excess of body fat.

OBJECTIVE

We assessed the degree of misclassification on the diagnosis of obesity using BMI as compared with direct body fat percentage (BF%) determination and compared the cardiovascular and metabolic risk of non-obese and obese BMI-classified subjects with similar BF%.

DESIGN

We performed a cross-sectional study.

SUBJECTS

A total of 6123 (924 lean, 1637 overweight and 3562 obese classified according to BMI) Caucasian subjects (69% females), aged 18-80 years.

METHODS

BMI, BF% determined by air displacement plethysmography and well-established blood markers of insulin sensitivity, lipid profile and cardiovascular risk were measured.

RESULTS

We found that 29% of subjects classified as lean and 80% of individuals classified as overweight according to BMI had a BF% within the obesity range. Importantly, the levels of cardiometabolic risk factors, such as C-reactive protein, were higher in lean and overweight BMI-classified subjects with BF% within the obesity range (men 4.3 ± 9.2, women 4.9 ± 19.5 mg l(-1)) as well as in obese BMI-classified individuals (men 4.2 ± 5.5, women 5.1 ± 13.2 mg l(-1)) compared with lean volunteers with normal body fat amounts (men 0.9 ± 0.5, women 2.1 ± 2.6 mg l(-1); P<0.001 for both genders).

CONCLUSION

Given the elevated concentrations of cardiometabolic risk factors reported herein in non-obese individuals according to BMI but obese based on body fat, the inclusion of body composition measurements together with morbidity evaluation in the routine medical practice both for the diagnosis and the decision-making for instauration of the most appropriate treatment of obesity is desirable.

Overweight and obesity in women with physical disabilities: associations with demographic and disability characteristics and secondary conditions

BACKGROUND

This cross-sectional study was designed to examine weight in association with demographic and disability characteristics and secondary conditions in a sample of community living women with physical disabilities.

METHODS

443 predominantly ethnic minority women with physical disabilities were recruited through public and private health clinics and community organizations. They completed questionnaires including measures of body mass index and a health conditions checklist.

RESULTS

Data showed that nearly three-quarters of the sample were overweight (26.6%) or obese (47.6%) with 14% extremely obese. Obesity was highest among middle aged women (aged 45-54, 52.7%; aged 55-64, 52.5%; compared to aged 18-44, 37.8%; or aged ≥65, 39.1%). Black (84.0%) and Hispanic women (83.8%) were more likely to be overweight or obese compared to non-Hispanic white women (56.7%). Women with joint and connective tissue diseases and women with more extensive functional limitations were more likely to have excess weight. Disability factors were more strongly associated with excess weight than demographic factors other than age. Weight classification was significantly related to whether or not the women had ever had diabetes or blood pressure problems. Diabetes was reported 4 times as often as among women in general (36.3% versus 8.9%), and hypertension nearly twice as often (56.2% versus 30.9%).

CONCLUSIONS

These findings indicate extremely high rates of overweight and obesity in women with physical disabilities, a growing population greatly in need of effective weight management interventions. Overweight and obesity in combination with disability in women was associated with disproportionately high rates of diabetes and hypertension.

The moderating impact of lifestyle factors on sex steroids, sexual activities and aging in Asian men

The present study sought to evaluate the relative associations of exercise, sleep and other lifestyle habits with aging, sex hormones, percent body fat (%BF) and sexual activities in men living in the community. A better understanding of this complex interrelationship is important in helping the formulation of modalities for a holistic approach to the management of aging men. The results showed that age is a major determinant for many physiological parameters, including sleep, hormonal and metabolic parameters, some lifestyle factors and sexual activities. Testosterone (T), bioavailable testosterone (BioT) and dehydroepiandrosterone sulphate (DHEAS) concentrations decreased with age, while estradiol (E2), sex hormone-binding globulin (SHBG) and %BF increased with age. In addition, there exist intricate associations among hormonal and lifestyle factors, %BF and age. High-intensity exercise and longer duration of sleep were associated with higher concentrations of T and BioT. T was shown to be associated positively with men who were engaged in masturbation. DHEAS was associated with men wanting more sex and with good morning penile rigidity. Older Singaporean men tended to sleep for shorter duration, but exercised more intensely than younger men. Coital and masturbation frequencies decreased with age, and a significantly greater number of younger men were engaged in masturbation. Relationship between the partners is a key determinant of sexuality in men. It appears that T may have a limited, while dehydroepiandrosterone (DHEA) have a greater role than previously suggest, as a motivational signal for sexual function in men. Both biological and psychosocial factors interact with each other to influence sexual functions in men. Hence, a biopsychosocial approach may be more appropriate for a more lasting resolution to sexual dysfunctions in men.

Integrating expression profiling and whole-genome association for dissection of fat traits in a porcine model

Traits related to fatness, important as economic factors in pork production, are associated with serious diseases in humans. Genetical genomics is a useful approach for studying the effects of genetic variation at the molecular level in biological systems. Here we applied a whole-genome association analysis to hepatic gene expression traits, focusing on transcripts with expression levels that correlated with fatness traits in a porcine model. A total of 150 crossbred pigs [Pietrain × (German Large White × German Landrace)] were studied for transcript levels in the liver. The 24K Affymetrix expression microarrays and 60K Illumina single nucleotide polymorphism (SNP) chips were used for genotyping. A total of 663 genes, whose expression significantly correlated with the trait "fat area," were analyzed for enrichment of functional annotation groups as defined in the Ingenuity Pathways Knowledge Base (IPKB). Genes involved in metabolism of various macromolecules and nutrients as well as functions related to dynamic cellular processes correlated with fatness traits. Regions affecting the transcription levels of these genes were mapped and revealed 4,727 expression quantitative trait loci (eQTL) at P < 10⁻⁵, including 448 cis-eQTL. In this study, genome-wide association analysis of trait-correlated expression was successfully used in a porcine model to display molecular networks and list genes relevant to fatness traits.

Community-Specific BMI Cutoff Points for South Indian Females

Objective. To analyze multiparameters related to total body composition, with specific emphasis on obesity in South Indian females, in order to derive community-specific BMI cutoff points. Patients and Methods. A total number of 87 females (of age 37.33 ± 13.12 years) from South Indian Chennai urban population participated in this clinical study. Body composition analysis and anthropometric measurements were acquired after conducting careful clinical examination. Results. BMI demonstrated high significance when normal group (21.02 ± 1.47 kg/m(2)) was compared with obese group (29.31 ± 3.95 kg/m(2)), P < 0.0001. BFM displayed high significance when normal group (14.92 ± 4.28 kg) was compared with obese group (29.94 ± 8.1 kg), P < 0.0001. Conclusion. Community-specific BMI cutoffs are necessary to assess obesity in different ethnic groups, and relying on WHO-based universal BMI cutoff points would be a wrong strategy.

Association of age and physical exercise with bodyweight and body composition in Asian Chinese men

BACKGROUND

The present study sought to examine the association between physical exercise as a lifestyle habit with anthropometric parameters and body composition and aging in men.

METHODS

Intensity of exercise was scored as metabolic equivalent-min/week (MET-min/week) from data of the questionnaire, while anthropometric parameters and body composition were carried out by standard measuring instruments and dual-energy X-ray absorptiometry scanner, respectively.

RESULTS

Age was associated with decreases in bodyweight, height, total lean mass and bone mass, but an increase in fat mass. The negative association of lean mass with age was predominantly due to the negative association of lean masses in the legs and arm, while the positive association of fat mass with age was primarily due to the positive association of fat masses in the trunk and abdomen. Exercise of intensity greater than 1000 MET-min/week was significantly associated with higher lean and bone masses and lower fat mass. The increase in lean mass was predominantly in the legs, while the decreases in fat mass were in the trunk and abdomen.

CONCLUSION

The study showed that the high intensity of physical exercise, equivalent to greater than 1000 MET-min/week, is required to effect beneficial changes in the body composition. Hence, results from the study support the importance of promoting a lifestyle habit of exercise of sufficient intensity in order to mitigate the increase risks of sarcopenia and obesity and their attendant ill effects on health in men as they age.

Sensitivity and specificity of the body mass index for the diagnosis of overweight/obesity in elderly

The aim of this article was to verify the sensitivity and specificity of the body mass index (BMI) cut-off points proposed by the World Health Organization (WHO) and the Nutrition Screening Initiative (NSI) for the diagnosis of obesity in the elderly. A cross-sectional study was made with 180 healthy elderly subjects from Florianópolis, Santa Catarina State, Brazil. Body fat percentage (%BF) was determined using DEXA (dual energy X-ray absorptiometry). The BMI cut-off point of the NSI offers better sensitivity and specificity for men (73.7% and 72.5% respectively). For women, the lower the cut-off point the better the sensitivity, with a BMI of 25kg/m² (sensitivity of 76.3% and specificity of 100%) being the most accurate for diagnosing obesity in elderly women. The WHO cut-off point offered very low sensitivity (28.9%). The results of this investigation lead to the conclusion that the cut-off points proposed by the WHO and the ones adopted by the NSI and by Lipschitz are not good indicators of obesity for the elderly of either sex, since they offer low sensitivity.

Similarity in percent body fat between white and Vietnamese women: implication for a universal definition of obesity

It has been widely assumed that for a given BMI, Asians have higher percent body fat (PBF) than whites, and that the BMI threshold for defining obesity in Asians should be lower than the threshold for whites. This study sought to test this assumption by comparing the PBF between US white and Vietnamese women. The study was designed as a comparative cross-sectional investigation. In the first study, 210 Vietnamese women ages between 50 and 85 were randomly selected from various districts in Ho Chi Minh City (Vietnam). In the second study, 419 women of the same age range were randomly selected from the Rancho Bernardo Study (San Diego, CA). In both studies, lean mass (LM) and fat mass (FM) were measured by dual-energy X-ray absorptiometry (DXA) (QDR 4500; Hologic). PBF was derived as FM over body weight. Compared with Vietnamese women, white women had much more FM (24.8 +/- 8.1 kg vs. 18.8 +/- 4.9 kg; P < 0.0001) and greater PBF (36.4 +/- 6.5% vs. 35.0 +/- 6.2%; P = 0.012). However, there was no significant difference in PBF between the two groups after matching for BMI (35.1 +/- 6.2% vs. 35.0 +/- 5.7%; P = 0.87) or for age and BMI (35.6 +/- 5.1% vs. 35.8 +/- 5.9%; P = 0.79). Using the criteria of BMI >or=30, 19% of US white women and 5% of Vietnamese women were classified as obese. Approximately 54% of US white women and 53% of Vietnamese women had their PBF >35% (P = 0.80). Although white women had greater BMI, body weight, and FM than Vietnamese women, their PBF was virtually identical. Further research is required to derive a more appropriate BMI threshold for defining obesity for Asian women.

Developing waist-to-height ratio cut-offs to define overweight and obesity in children and adolescents

OBJECTIVE

The waist-to-height ratio (WHtR) assesses abdominal adiposity and has been proposed to be of greater value in predicting obesity-related cardiovascular health risks in children than BMI. The present study aims to develop WHtR cut-offs for overweight and obesity based on the 85th and 95th percentiles for the percentage body fat (%BF) in a cohort of children and adolescents.

DESIGN

Waist circumference (WC), height, triceps and subscapular skinfolds were used to calculate WHtR and %BF. Correlations between WHtR and %BF and WHtR/mid-abdominal skinfold were made. Receiver-operating characteristic (ROC) curve analysis was used to select WHtR cut-offs to define overweight and obesity. Subjects were grouped by WHtR cut-offs, and mean values for anthropometry, blood lipids and blood pressure (BP) variables were compared.

SETTING

Australian primary and secondary schools.

SUBJECTS

A total of 2773 male (M) and female (F) subjects of the 1985 Australian Health and Fitness Survey, aged 8-16 years.

RESULTS

Correlation coefficients between WHtR and %BF were M: r = 0.73, F: r = 0.60, P < 0.01 and WHtR/mid-abdominal skinfold were M: r = 0.78, F: r = 0.65, P < 0.01. WHtR of 0.46(M) and 0.45(F) best identified subjects with > or = 85th percentile for %BF and 0.48(M) and 0.47(F) identified subjects with > or = 95th percentile for %BF. When comparing the highest WHtR group to the lowest, both sexes had significantly higher means for weight, WC, %BF, TG (male subjects only), systolic BP (female subjects only) and lower means for HDL cholesterol (P < 0.05).

CONCLUSIONS

WHtR is useful in clinical and population health as it identifies children with higher %BF at greater risk of developing weight-related CVD at an earlier age.

Increased fat mass and high incidence of overweight despite low body mass index in patients with spinal muscular atrophy

Body composition is sparsely described in spinal muscular atrophy (SMA). Body (BMI, mass/height in m(2)), fat-free (FFMI, lean mass/height in m(2)) and fat (FMI, fat mass/height in m(2)) mass indexes were estimated in 25 children (aged 5-18) with SMA (2 type I, 13 type II, 10 type III) using dual-energy radiograph absorptiometry and anthropometric data referenced to gender and age-matched healthy children (NHANES III, New York Pediatric Rosetta Body Project). BMI was 50th percentile in 11 (44%) and 85th in 5 (20%). FFMI was reduced (p<0.005) and FMI was increased (p<0.005) in the overall study cohort. FMI was 50th, 85th and 95th percentiles in 19 (76%), 10 (40%) and 5 (20%) subjects, respectively. Using a receiver operator characteristic curve, BMI above 75th, 50th and 3rd percentiles maximized sensitivity and specificity for FMI 95th, 85th and 50th percentiles, respectively. Children with SMA have reduced lean and increased fat mass compared to healthy children. Obesity is a potentially important modifiable source of morbidity in SMA.

Interethnic differences in the accuracy of anthropometric indicators of obesity in screening for high risk of coronary heart disease

BACKGROUND

Cut points for defining obesity have been derived from mortality data among Whites from Europe and the United States and their accuracy to screen for high risk of coronary heart disease (CHD) in other ethnic groups has been questioned.

OBJECTIVE

To compare the accuracy and to define ethnic and gender-specific optimal cut points for body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) when they are used in screening for high risk of CHD in the Latin-American and the US populations.

METHODS

We estimated the accuracy and optimal cut points for BMI, WC and WHR to screen for CHD risk in Latin Americans (n=18 976), non-Hispanic Whites (Whites; n=8956), non-Hispanic Blacks (Blacks; n=5205) and Hispanics (n=5803). High risk of CHD was defined as a 10-year risk > or =20% (Framingham equation). The area under the receiver operator characteristic curve (AUC) and the misclassification-cost term were used to assess accuracy and to identify optimal cut points.

RESULTS

WHR had the highest AUC in all ethnic groups (from 0.75 to 0.82) and BMI had the lowest (from 0.50 to 0.59). Optimal cut point for BMI was similar across ethnic/gender groups (27 kg/m(2)). In women, cut points for WC (94 cm) and WHR (0.91) were consistent by ethnicity. In men, cut points for WC and WHR varied significantly with ethnicity: from 91 cm in Latin Americans to 102 cm in Whites, and from 0.94 in Latin Americans to 0.99 in Hispanics, respectively.

CONCLUSION

WHR is the most accurate anthropometric indicator to screen for high risk of CHD, whereas BMI is almost uninformative. The same BMI cut point should be used in all men and women. Unique cut points for WC and WHR should be used in all women, but ethnic-specific cut points seem warranted among men.

The relationship between skinfold thickness and body mass index in North European Caucasian and East Asian women with anorexia nervosa: implications for diagnosis and management

OBJECTIVE

To investigate the relationship between skinfold thickness and body mass index (BMI) in North European Caucasian and East Asian young women with and without anorexia nervosa (AN) in two countries.

METHOD

Height, weight and skinfold thicknesses were assessed in 137 young women with and without AN, in Australia and Singapore. The relationship between BMI and the sum of triceps, biceps, subscapular and iliac crest skinfolds was analysed with clinical status, ethnicity, age and country of residence as covariates.

RESULTS

For the same BMI, women with AN had significantly smaller sums of skinfolds than women without AN. East Asian women both with and without AN had significantly greater skinfold sums than their North European Caucasian counterparts after adjusting for BMI.

CONCLUSION

Lower BMI goals may be appropriate when managing AN patients of East Asian ancestry and the weight for height diagnostic criterion should be reconsidered for this group.

Factors affecting outcome after total knee arthroplasty in patients with diabetes mellitus

PURPOSE

To compare the clinical outcome and complications following total knee arthroplasty (TKA) in diabetic and non-diabetic patients, and to identify diabetes-related risk factors for negative outcomes.

MATERIALS AND METHODS

222 primary TKAs in patients with diabetes were evaluated using Knee Society scores and Hospital for Special Surgery score. Postoperative complications were reviewed retrospectively. The mean follow-up was 53.2 months. The effect of diabetes-related factors and comparison with a matched control group were analyzed statistically.

RESULTS

Significant improvements were noted in all the scores after TKA (p < 0.05). There was no statistical difference in clinical sores between the diabetic and non-diabetic patients. In multivariate analysis associating age, gender and body mass index with pain and knee score at the latest follow-up, the average knee scores in normal and overweight group were found to be significantly higher than those in the obese group. The diabetic patients had an increased overall incidence of postoperative complications (17.6%) compared with the control group (8.1%) (p < 0.05). Particularly, the rate of wound complications such as skin necrosis, bulla formation or erythema with drainage was higher in the diabetic group (p < 0.05). Diabetes-related factors did not influence the incidence of complications. Associated diseases were the only significant risk factors correlated with wound complications and meniscal bearing dislodgement.

CONCLUSION

Patients with diabetes can benefit from TKA, even though diabetic patients are at an increased risk for overall postoperative and wound complications. Preoperative factors such as obesity and associated diseases may adversely affect the clinical outcome of TKA in diabetic patients.

Differential impact of aging and gender on lipid and lipoprotein profiles in a cohort of healthy Chinese Singaporeans

AIM

To evaluate the impact of age and gender on lipid and lipoprotein profiles and the burden of dyslipidemia in a cohort of healthy Chinese Singaporean.

METHODS

A total of 1 775 healthy Chinese, 536 men and 1 239 women aged between 30 and 70 years old were involved in the present study.

RESULTS

Gender differences in all lipid and lipoprotein levels were clearly evident. Singaporean Chinese men have significantly higher levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C) and total cholesterol/high density lipoprotein-cholesterol (TC/HDL-C), and lower levels of HDL-C than women. Although lipid and lipoprotein levels in men did not change in the different age groups, those in women, especially TC, LDL-C and TC/HDL-C, were significantly higher in older women (> 50 years old) than corresponding levels in younger women (30-46 years old). Furthermore, TG was significantly correlated with lipids and lipoproteins differently in men and women. If 100 mg/dL of LDL-C were to be adopted as the therapeutic cut-off level, then the burden of care will be huge as approximately 90% of both Chinese men and women have LDL-C greater than 100 mg/dL.

CONCLUSION

In light of the findings of the present study, we suggest that preventive measures to promote the reduction in risk of coronary heart disease (CHD) must address the high proportion of men and women with high LDL-C, and that these measures should take into account both the gender and age factors. For men, reduction of high cholesterol must start early in life, whereas for women, steps must be taken earlier to mitigate the anticipated sharp increase in risk, especially after menopause.

Interactions among age, adiposity, bodyweight, lifestyle factors and sex steroid hormones in healthy Singaporean Chinese men

AIM

To examine the inter-relationships among age, lifestyle factors, anthropometric parameters, percent body fat and steroid hormone parameters in 531 healthy Singaporean Chinese men aged between 29 and 72 years old.

METHODS

Various lifestyle parameters were quantified through a survey, and testosterone (T), estradiol (E2), dehydroepiandrosterone sulphate (DHEAS) and sex hormone binding globulin (SHBG) were measured using established methods. Anthropometric parameters were collected and computed, and percent body fat (Siri) was measured using the DEXA scanner.

RESULTS

SHBG, DHEAS, bioavailable-T (Bio-T), E2, Siri, Ht, W/H, W/Ht and work stress were independently correlated with age. Using multivariate analyses and adjusting for age and other related factors, exercise, smoking and alcohol consumption have positive impacts on androgen levels and body composition. However, black and green tea consumption was associated with negative effects on body composition and with higher levels of E2 and Free Estradiol Index (FEI). Men with shorter sleep duration had significantly lower T levels as compared to those with 6 h or more of nightly sleep. Higher T levels were associated with lower levels of adiposity and other indices of adiposity, whereas higher E2 levels were related to higher levels of adiposity. Men with higher DHEAS were significantly taller and heavier than those with low DHEAS levels.

CONCLUSION

The study showed the close interactions among the gonadal/adrenal and metabolic compartments, with age being a key determinant in their interactions. Lifestyle factors such as exercise, smoking, sleeping and alcohol and tea consumption might play significantly roles in determining the status of health in men.

Body Mass Index as a Predictor of Percent Fat in College Athletes and Nonathletes

INTRODUCTION

Body mass index (BMI) is used as a surrogate for percent fat (% fat) in classifying obesity. However, there is no established criterion for % fat and health risk, and few studies have examined the accuracy/validity of BMI as a measure of % fat. By default, BMI is used to classify athletes and young adults as obese. Consequently, it is critical to understand the accuracy of BMI in these populations. The purposes of this study were 1) to describe the relationship between BMI and % fat, and 2) to determine the accuracy of BMI as a measure of % fat in college athletes and nonathletes.

METHODS

A total of 226 college-aged athletes and 213 college-aged nonathletes participated. Three male groups (athletes, football linemen, and nonathletes) and two female groups (athletes and nonathletes) were created. BMI was calculated. Percent fat was determined via BOD POD. BMI >or= 25 kg.m(-2) was used to define overweight. Twenty percent fat for males and 33% fat for females were used to define overfatness. Using % fat as the criterion, sensitivity and specificity of BMI were calculated. Receiver operator characteristic curves determined optimal BMI cut points for % fat.

RESULTS

Sensitivity was high (0.83-1.0) and specificity was low (0.27-0.66) in male athletes, male nonathletes, and female athletes. Sensitivity was high in linemen (1.0). Sensitivity was low (0.56) and specificity was high (0.90) in female nonathletes. Optimal BMI cut points for male athletes, linemen, male nonathletes, female athletes, and female nonathletes were 27.9, 34.1, 26.5, 27.7, and 24.0 kg.m(-2), respectively.

CONCLUSIONS

BMI should be used cautiously when classifying fatness in college athletes and nonathletes. Our results support the need for different BMI classifications of overweight in these populations.

Body mass index and body composition measures by dual x-ray absorptiometry in patients aged 10 to 21 years with spinal cord injury

BACKGROUND/OBJECTIVE

To determine the body composition of adolescents with spinal cord injury (SCI) and to assess whether established cutoff values for obesity determined by body mass index (BMI) are valid for this population.

METHODS

Sixty patients, aged 10-21 years, with traumatic SCI (50 with paraplegia and 10 with tetraplegia) were compared with 60 gender-, age-, and BMI-matched controls (CTRL). Dual-energy x-ray absorptiometry was used to estimate regional and total bone mineral content, lean tissue mass, fat tissue mass, and body fat percentage. BMI was calculated from measured weight and stature (kg/m2).

RESULTS

Total percent body fat was significantly higher in the paraplegia group (31.4% +/- 1.2%; mean +/- SE) than in the tetraplegia and CTRL groups (25.7% +/- 2.7% and 22.9% +/- 1.1%, respectively). This change in percent total body fat was associated with a reduction of lean tissue mass in the paraplegia (37.6 +/- 1.1 kg; mean +/- SE) and tetraplegia (32.8 +/- 2.5 kg) subjects as compared to the CTRL group (46.2 +/- 1.0 kg; P < 0.001). Total fat mass was significantly greater in the paraplegia group (19.3 +/- 1.3 kg) than the CTRL and tetraplegia groups (14.9 +/- 1.2 kg and 11.7 +/- 3.0 kg, respectively). Regional measurements revealed that the greatest reduction of lean tissue mass in the SCI subjects occurred in the lower extremities, followed by the trunk. As a result of these changes in body composition, the optimal BMI for classifying obesity (trunk fat percent >30 in males and >35 in females) in subjects with SCI was 19 kg/m2 as compared to 25 kg/m2 in able-bodied subjects.

CONCLUSIONS

Patients aged 10 to 21 years with SCI have significantly decreased lean tissue mass and bone mineral content, and increased fat mass. As a result, traditional BMI cutoff criteria significantly underestimate obesity in this population. New clinically applicable criteria to define obesity should be established for SCI children and adolescents with SCI.

Waist circumference correlates with metabolic syndrome indicators better than percentage fat

OBJECTIVE

Percent fat is often considered the reference for establishing the magnitude of adipose tissue accumulation and the risk of excess adiposity. However, the increasing recognition of a strong link between central adiposity and metabolic disturbances led us to test whether waist circumference (WC) is more highly correlated with metabolic syndrome components than percent fat and other related anthropometric measures such as BMI.

RESEARCH METHODS AND PROCEDURES

BMI, WC, and percent fat, measured by DXA, were evaluated in 1010 healthy white and African-American men and women [age, 48.3 +/- 17.2 (standard deviation) years; BMI, 27.0 +/- 5.3 kg/m(2)]. The associations of BMI, WC, and percent fat with age and laboratory-adjusted health risk indicators (i.e., serum glucose, insulin, triglycerides, high-density lipoprotein cholesterol, blood pressure) in each sex and ethnicity group were examined.

RESULTS

For 18 of 24 comparisons, the age- and laboratory-adjusted correlations were lowest for percent fat and in 16 of 24 comparisons were highest for WC. Fifteen of the between-method differences reached statistical significance. With health risk indicator as the dependent variable and anthropometric measures as the independent variable, the contribution of percent fat to the WC regression model was not statistically significant; in contrast, adding WC to the percent fat regression model did make a significant independent contribution for most health risk indicators.

DISCUSSION

WC had the strongest associations with health risk indicators, followed by BMI. Although percent fat is a useful measure of overall adiposity, health risks are best represented by the simply measured WC.