BMI, fat and muscle differences in urban women of five ethnicities from two countries

Low-fat dietary pattern and change in body-composition traits in the Women's Health Initiative Dietary Modification Trial

BACKGROUND

The Women's Health Initiative Dietary Modification (DM) Trial was a randomized controlled trial that compared the effects of a low-fat (≤20% of total energy) or a usual diet in relation to chronic disease risk in postmenopausal women.

OBJECTIVE

We characterized long-term body-composition changes associated with the DM trial and potential modifiers of these associations.

DESIGN

In the DM trial, 48,835 women aged 50-79 y were randomly assigned to intervention (40%) or comparison (60%) groups. We studied a subset with whole-body dual-energy X-ray absorptiometry scans at baseline and during follow-up. Changes in fat mass (FM), lean mass (LM), and percentage body fat between the intervention (n = 1580) and comparison (n = 2731) groups at years 1, 3, and 6 were compared. By using generalized estimating equations, we calculated overall differences between groups and tested for interactions with age, diabetes, race-ethnicity (white, black, and Hispanic), body mass index (BMI), and hormone therapy (HT).

RESULTS

The intervention women experienced significantly greater reductions in percentage body fat, FM, and LM at years 1 and 3 than did women in the comparison group (all P < 0.05). At year 6, only the FM change was significantly different between groups. Overall, the intervention was associated with reductions in percentage body fat (-0.8%; 95% CI: -1.0%, -0.6%), FM (-1.1 kg; 95% CI: -1.3, -0.8 kg), and LM (-0.17 kg; 95% CI: -0.28, -0.06 kg) during follow-up (all P < 0.003). Intervention associations varied by race-ethnicity, BMI, diabetes, and HT and remained significant after adjustment for physical activity.

CONCLUSION

This intervention was associated with modest long-term body-composition changes; the findings were more robust in years 1 and 3. This trial was registered at clinicaltrials.gov as NCT00000611.

Ethnic differences in serum lipoproteins and their determinants in South African women

The objective of the study was to characterize ethnic differences in lipid levels and low-density lipoprotein (LDL) particle size and subclasses in black and white South African women and to explore the associations with insulin sensitivity (S(I)), body composition, and lifestyle factors. Fasting serum lipids and LDL size and subclasses, body composition (dual-energy x-ray absorptiometry), and S(I) (frequently sampled intravenous glucose tolerance test) were measured in normal-weight (body mass index <25 kg/m(2)) black (n = 15) and white (n = 15), and obese (body mass index >30 kg/m(2)) black (n = 13) and white (n = 13) women. Normal-weight and obese black women had lower triglycerides (0.59 +/- 0.09 and 0.77 +/- 0.10 vs 0.89 +/- 0.09 and 0.93 +/- 0.10 mmol/L, P < .05) and high-density lipoprotein cholesterol (1.2 +/- 0.1 and 1.1 +/- 0.1 vs 1.7 +/- 0.1 and 1.6 +/- 0.3 mmol/L, P < .01) than white women. The LDL particle size was not different, but obese black women had more LDL subclass IV (17.3% +/- 1.0% vs 12.5% +/- 1.0%, P < .01). In white women, triglycerides and LDL particle size correlated with S(I) (P < .01), whereas cholesterol levels correlated with body fat (P < .05). Low socioeconomic status, low dietary protein intake, and injectable contraceptive use were the major determinants of unfavorable lipid profiles in black women. Black women had lower triglyceride and high-density lipoprotein cholesterol levels and more small dense LDL particles than white women. The major determinants of serum lipids in black women were socioeconomic status and lifestyle factors, whereas in white women, S(I) and body composition most closely correlated with serum lipids.

Body mass index and waist circumference cutoffs to define obesity in indigenous New Zealanders

BACKGROUND

The suggestion that body mass index (BMI) cutoffs to define obesity should differ in persons of Polynesian descent compared with Europeans is based principally on the observation that persons of Polynesian descent have a relatively higher proportion of lean body mass for a given BMI.

OBJECTIVES

The objectives were to determine whether the relation between BMI, waist circumference, and metabolic comorbidity differs in the 2 major ethnic groups in New Zealand and to ascertain whether ethnicity-specific BMI and waist circumference cutoffs for obesity are justified for Māori (indigenous New Zealanders).

DESIGN

Subjects included a convenience sample of 1539 men and women aged 17-82 y (47% Māori, 53% white) with measures of BMI, waist circumference, blood pressure, fasting insulin, glucose, and lipids. The sensitivity and specificity of BMI (in kg/m(2); 30 and 32), waist circumference (80 and 88 cm in women, 94 and 102 cm in men), and waist-to-height ratio (WHtR; > or =0.6) in relation to insulin sensitivity, insulin resistance, and the metabolic syndrome were determined. Receiver operating characteristic curves and areas under the curve (AUCs) were also calculated.

RESULTS

No ethnic or sex differences between AUCs were observed for BMI, waist circumference, or WHtR, which showed that these anthropometric measures perform similarly in Māori and European men and women and correctly discriminate between those with and without insulin resistance or the metabolic syndrome 79-87% of the time. Any increase in specificity from a higher BMI cutoff of 32 in Māori was offset by appreciable reductions in sensitivity.

CONCLUSION

These findings argue against having different BMI or waist circumference cutoffs for people of Polynesian descent.

Anthropometric measures and glucose levels in a large multi-ethnic cohort of individuals at risk of developing type 2 diabetes

AIMS/HYPOTHESES

We determined: (1) which of BMI, waist circumference, hip circumference and WHR has the strongest association and explanatory power for newly diagnosed type 2 diabetes and glucose status; and (2) the impact of considering two measures simultaneously. We also explored variation in anthropometric associations by sex and ethnicity.

METHODS

We performed cross-sectional analysis of 22,293 men and women who were from five ethnic groups and 21 countries, and at risk of developing type 2 diabetes. Standardised anthropometric associations with type 2 diabetes and AUC of glucose status from OGTT (AUC(OGTT)) were determined using multiple regression. Explanatory power was assessed using the c-statistic and adjusted r (2).

RESULTS

An increase in BMI, waist circumference or WHR had similar positive associations with type 2 diabetes, AUC(OGTT) and explanatory power after adjustment for age, sex, smoking and ethnicity (p < 0.01). However, using BMI and WHR together resulted in greater explanatory power than with other models (p < 0.01). Associations were strongest when waist circumference and hip circumference were used together, a combination that had greater explanatory power than other models except for BMI and WHR together (p < 0.01). Results were directionally similar according to sex and ethnicity; however, significant variations in associations were observed among these subgroups.

CONCLUSIONS/INTERPRETATION

The combination of BMI and WHR, or of waist circumference and hip circumference has the best explanatory power for type 2 diabetes and glucose status compared with a single anthropometric measure. Measurement of waist circumference and hip circumference is required to optimally identify people at risk of type 2 diabetes and people with elevated glucose levels.

Dual-energy X-ray absorptiometry and anthropometric estimates of visceral fat in Black and White South African Women

Visceral adipose tissue (VAT) is associated with increased risk for cardiovascular disease, and therefore, accurate methods to estimate VAT have been investigated. Computerized tomography (CT) is the gold standard measure of VAT, but its use is limited. We therefore compared waist measures and two dual-energy X-ray absorptiometry (DXA) methods (Ley and Lunar) that quantify abdominal regions of interest (ROIs) to CT-derived VAT in 166 black and 143 white South African women. Anthropometry, DXA ROI, and VAT (CT at L4-L5) were measured. Black women were younger (P < 0.001), shorter (P < 0.001), and had higher body fat (P < 0.05) than white women. There were no ethnic differences in waist (89.7 +/- 18.2 cm vs. 90.1 +/- 15.6 cm), waist:height ratio (WHtR, 0.56 +/- 0.12 vs. 0.54 +/- 0.09), or DXA ROI (Ley: 2.2 +/- 1.5 vs. 2.1 +/- 1.4; Lunar: 2.3 +/- 1.4 vs. 2.3 +/- 1.5), but black women had less VAT, after adjusting for age, height, weight, and fat mass (76 +/- 34 cm(2) vs. 98 +/- 35 cm(2); P < 0.001). Ley ROI and Lunar ROI were correlated in black (r = 0.983) and white (r = 0.988) women. VAT correlated with DXA ROI (Ley: r = 0.729 and r = 0.838, P < 0.01; Lunar: r = 0.739 and r = 0.847, P < 0.01) in black and white women, but with increasing ROI android fatness, black women had less VAT. Similarly, VAT was associated with waist (r = 0.732 and r = 0.836, P < 0.01) and WHtR (r = 0.721 and r = 0.824, P < 0.01) in black and white women. In conclusion, although DXA-derived ROIs correlate well with VAT as measured by CT, they are no better than waist or WHtR. Neither DXA nor anthropometric measures are able to accurately distinguish between high and low levels of VAT between population groups.

Ethnic differences in body composition and the associated metabolic profile: a comparative study between Asians and Caucasians

It is estimated that Asia will be the home of more than 100 million people with type 2 diabetes by the year of 2025. This region combines a high proportion of the world's population with rapidly rising diabetes prevalence rates. The increase in diabetes in Asia differs from that reported in other parts of the world: it has developed in a shorter time, in a younger age group, and in people with lower body-mass index (BMI). Studies reported that for the same BMI, Asians have a higher body fat percentage, a prominent abdominal obesity, a higher intramyocellular lipid and/or a higher liver fat content compared to Caucasians. These characteristics may contribute to a higher predisposition to insulin resistance at a lesser degree of obesity than Caucasians. The differences in body composition are more pronounced depending on the region. For the same BMI, among three major ethnic groups in Asia, Asian Indians have the highest body fat, followed by Malay and Chinese. Lower insulin sensitivity is already observed in Asian Indian adolescents with a higher body fat and abdominal obesity compared to Caucasian adolescents. In general, Asian adolescents share the same feature of body composition such as higher body subcutaneous fat, lower appendicular skeletal muscle and lower gynoid fat compared to Caucasian adolescents. This unfavourable body composition may predispose to the development of insulin resistance at later age. Genetics may play a role and the interaction with environmental factors (changes in lifestyle) could increase the risk of developing the metabolic syndrome.

Evaluation of nutritional status in older persons: nutritional screening and assessment

PURPOSE OF REVIEW

Malnutrition is highly prevalent in the older population. It is associated with declining functionality and relevant health deficits. This review presents the principles of successful nutritional screening and assessment in older persons.

RECENT FINDINGS

Although no gold standard for the diagnosis of malnutrition can serve as reference, a large number of nutritional screening tools have been developed during the past two decades. For efficient screening, the most appropriate tool has to be selected based on setting and practicability. The screening intervals have to be chosen according to the population screened. Although screening has to be performed routinely and systematically in a very practical and efficient manner, nutritional assessment has to be individualized to provide information on the grade of malnutrition and its cause. The development of a local guideline that reflects local expertise and resources will prove essential for successful nutritional management.

CONCLUSION

Nutritional screening and assessment should be a standard of care for older persons. It has to be considered as a clearly defined two-step procedure, which has to reflect setting and local resources. Further adaptations of the available screening tools with regard to ethnic characteristics are indicated.

Length of residence and obesity among immigrants in Spain

Objective

Various studies in the USA and Canada have consistently shown a positive association between length of residence of immigrants and obesity. Studies in European countries have obtained less consistent results. The present work assesses the influence of length of residence on the frequency of obesity in immigrants in the city of Madrid, Spain.

Design

We studied a sample of 7155 persons aged 18 years and over residing in the city of Madrid, who were was surveyed between November 2004 and May 2005. Information was collected on immigrant status (country of birth), length of residence in Spain, obesity, sociodemographic characteristics and lifestyle.

Results

Compared with the Spanish population, the odds for obesity in the immigrant population by length of residence was less than one in all groups, becoming closer to one with increasing time of residence (OR = 0·67, 0·73 and 0·81 for immigrants with less than 2, 2–4 and 5–9 years of residence in Spain, respectively), up to 10 or more years of residence, when it declined (OR = 0·69). The magnitude of this association was considerably reduced after adjusting for sociodemographic variables and for perceived health, but was not further modified after adjusting for lifestyle variables.

Conclusions

Length of residence of immigrants in the city of Madrid is not associated with the frequency of obesity. It is possible that the circumstances immigrants encounter after arriving in Spain do not involve an overexposure to factors favouring obesity, relative to those they bring with them.

Body mass index as a phenotypic expression of adiposity: quantitative contribution of muscularity in a population-based sample

OBJECTIVE

Although widely applied as a phenotypic expression of adiposity in population and gene-search studies, body mass index (BMI) is also acknowledged to reflect muscularity even though relevant studies directly measuring skeletal muscle (SM) mass are lacking. The current study aimed to fill this important gap by applying advanced imaging methods to test the hypothesis that, after controlling first for adiposity, SM mass is also a significant determinant of BMI in a population-based sample.

DESIGN

Whole-body magnetic resonance imaging scans were completed in Coronary Artery Risk Development in Young Adults study subjects aged 33-45 years. Physical activity (PA) levels, alcohol intake and adequacy of food intake were assessed by standardized questionnaires.

SUBJECTS

The study included 58 African-American (AA) and 78 Caucasian (C) men; and 63 AA and 64 C women.

MEASUREMENTS

Whole-body adipose tissue (AT) and SM volumes.

RESULTS

AT was significantly predicted by not only BMI, but also PA and alcohol intake with total model R (2)'s of 0.68 (P<0.0001) for men and 0.89 (P<0.0001) for women. Men had more SM than AT at all levels of BMI whereas SM predominated in women at lower BMIs (C<26 kg/m(2); AA<28 kg/m(2)). In men, both AT and SM contributed a similar proportion of between-subject variation in BMI. In contrast, in women AT contributed approximately 30% more than SM to the variation in BMI. Developed allometric models indicated SM associations with AT, PA and race after adjusting for height. There was little association of age, lifestyle factors or race with BMI after controlling for both AT and SM.

CONCLUSION

Variation in muscularity provides a mechanistic basis for the previously observed nonspecificity of BMI as a phenotypic expression of adiposity. These quantitative observations have important implications when choosing adiposity measures in population and gene-search studies.

Ethnic variation in fat and lean body mass and the association with insulin resistance

CONTEXT

Body fat distribution varies among different ethnic groups, yet less is known regarding differences in lean mass and how this may affect insulin resistance.

OBJECTIVE

Our objective was to compare total body fat to lean mass ratio (F:LM) in Aboriginal, Chinese, European, and South Asian individuals with differences in insulin resistance.

PARTICIPANTS, DESIGN, AND SETTING

Aboriginal (196), Chinese (222), European (202), and South Asian (208) individuals were recruited across a range of body mass index to participate in this cross-sectional community study.

MAIN OUTCOME MEASURES

Total body fat, lean mass, and insulin resistance were assessed using homeostasis model assessment (HOMA).

RESULTS

After adjustment for confounders and at a given body fat, South Asian men had less lean mass than Aboriginal [3.42 kg less; 95% confidence interval (CI) = 1.55-5.29], Chinese (3.01 kg less; 95% CI = 1.33-4.70), and European (3.57 kg less; 95% CI = 1.82-5.33) men, whereas South Asian women had less lean mass than Aboriginal (1.98 kg less; 95% CI = 0.45-3.50), Chinese (2.24 kg less; 95% CI = 0.81-3.68), and European (2.97 kg less; 95% CI = 1.67-4.27) women. In adjusted models, F:LM was higher in South Asian compared with Chinese and European men and higher in South Asian compared with Aboriginal, Chinese, and European women (P < 0.01 for all). Insulin and HOMA were greatest in South Asians after adjustment; however, these differences were no longer apparent when F:LM was considered.

CONCLUSIONS

South Asians have a phenotype of high fat mass and low lean mass, which may account for greater levels of insulin and HOMA compared with other ethnic groups.

Comparison of body fatness measurements by near-infrared reactance and dual-energy X-ray absorptiometry in normal-weight and obese black and white women

The aim of the present study was to compare body fat percent (BF %) using single-site near-IR reactance (NIR) and dual-energy X-ray absorptiometry (DXA) in a cohort of normal-weight (BMI < 25 kg/m2) black (n 102) and white (n 71); and obese (BMI > or = 30 kg/m2) black (n 117) and white (n 41) South African women (18-45 years). NIR-derived BF % was significantly correlated with DXA-derived BF % in all groups: normal-weight black (r 0.55, 95 % CI: 0.40, 0.67, P < 0.001) and white (r 0.69, 95 % CI: 0.53, 0.79, P < 0.001) women; obese black (r 0.59, 95 % CI: 0.46, 0.70, P < 0.001) and white (r 0.56, 95 % CI: 0.30, 0.74, P < 0.001) women. NIR under-predicted BF% compared to DXA in black women (normal-weight, - 4.36 (sd 4.13) % and obese, - 3.41 (sd 3.72) %), while smaller mean differences were observed in white women (normal-weight, - 0.29 (sd 4.19) % and obese, - 0.81 (sd 3.09) %), irrespective of normal-weight or obese status (P < 0.001). In obese subjects, NIR-derived BF % did not measure values greater than approximately 45 %, while the maximum DXA-derived measure was 58 %. In conclusion, although there was a significant relationship between NIR- and DXA-derived BF %, NIR under-predicted BF % in normal-weight and obese black South African women compared to DXA, but to a greater extent in subjects with very high levels of adiposity (>45 %). The results of single-site NIR as a measure of BF % should therefore be interpreted with caution, particularly in women of African descent and in those with very high levels of adiposity.

Optimal waist cutpoint for screening for dysglycaemia and metabolic risk: evidence from a Maori cohort

We sought to identify the sex-specific cut-off in waist circumference which best identifies those with metabolic abnormalities consistent with the metabolic syndrome (MS) among Maori, the indigenous people of New Zealand of Polynesian origin. In 3816 self-identified Maori (2742 women, 1344 men) a 75 g oral glucose tolerance test, fasting lipid, anthropometric and blood pressure measurements were made. MS components were defined by Adult Treatment Panel (ATP) III criteria. Waist cut-off was defined using receiver operating characteristic (ROC) curve analysis to define the presence of at least two of the other MS components ( ≥ 2MS). Prevalence of ≥ 2MS was high (42·1 %). In males and females, waist was as good, or better, a predictor of ≥ 2MS (area under ROC 0·73 women, 0·68 men) as waist:hip ratio (0·66, 0·67), BMI (0·72, 0·68) or percentage body fat (0·70, 0·68). The prediction of dysglycaemia using anthropometric variables followed a similar pattern to ≥ 2MS. Waist circumference to predict ≥ 2MS or dysglycaemia in Maori women and men was 98 cm and 103 cm. Applying this cut-off to the International Diabetes Federation (IDF) criteria would identify 27·8 % (34·0 % males, 25·5 % females) with the MS with an OR for ≥ 2MS (adjusted for sex, smoking and age) of 3·5 (95 % CI 3·1, 4·0). Age >48 years, smoking and being male increased the odds of the MS. These waist cut-offs should be considered in both clinical practice and to optimise the definition of the MS for Maori. The validity of these criteria in other Polynesian groups should be confirmed.

Body size, body composition and fat distribution: comparative analysis of European, Maori, Pacific Island and Asian Indian adults

Although there is evidence that Asian Indians, Polynesians and Europeans differ in their body fat (BF)-BMI relationships, detailed comparative analysis of their underlying body composition and build characteristics is lacking. We investigated differences in the relationships between body fatness and BMI, fat distribution, muscularity, bone mineral mass, leg length and age-related changes in body composition between these ethnic groups. Cross-sectional analysis of 933 European, Maori, Pacific Island and Asian Indian adult volunteers was performed for total and percentage of BF, abdominal fat, thigh fat, appendicular muscle mass, bone mineral content and leg length measured by dual-energy X-ray absorptiometry. Asian Indian men and women (BMI of 24 and 26 kg/m2, respectively) had the same percentage of BF as Europeans with a BMI of 30 kg/m2 or Pacific men and women with BMI of 34 and 35 kg/m2, respectively. Asian Indians had more fat, both total and in the abdominal region, with less lean mass, skeletal muscle and bone mineral than all other ethnic groups. Leg length was relatively longer in Pacific men and Asian and Pacific women than in other ethnic groups. In Asian Indians, abdominal fat increased with increasing age, while the percentage of BF showed little change. In the other ethnic groups, both abdominal and total BF increased with age. In conclusion, ethnic differences in fat distribution, muscularity, bone mass and leg length may contribute to ethnic-specific relationships between body fatness and BMI. The use of universal BMI cut-off points may not be appropriate for the comparison of obesity prevalence between ethnic groups.

Total daily energy expenditure in black and white, lean and obese South African women

BACKGROUND/OBJECTIVES

In South Africa (SA), the prevalence of obesity in women is 56%, with black women being most at risk (62%). Studies in the United States have demonstrated ethnic differences in resting (REE) and total daily energy expenditure (TDEE) between African American (AA) and their white counterparts. We investigated whether differences in EE exist in black and white SA women, explaining, in part, the ethnic obesity prevalence differences.

SUBJECTS/METHODS

We measured REE, TDEE and physical activity EE (PAEE) in lean (BMI <25 kg m(-2)) and obese (BMI >30 kg m(-2)) SA women (N=44, 30+/-6 year). REE, TDEE, PAEE and total awake EE were measured during a 21 h stay in a respiration chamber.

RESULTS

Black and white subjects within obese and lean groups were not significantly different for age, mass, BMI and % body fat. However, fat-free mass (kg FFM) was consistently lower in the black women (P<0.01) in both weight groups. After adjusting EE measurements for differences in FFM, REE was not significantly different for either body weight or ethnicity, although 24 h TDEE (kJ) was significantly greater in the obese women (P<0.01) and white women (P<0.05). Total awake non-PAEE was not significantly different for either groups, while total awake time was only significantly lower for the lean groups (P<0.01). Total PAEE (kJ min(-1)) was significantly lower in the lean (P<0.001) and black groups (P<0.01).

CONCLUSIONS

In this sample of matched, lean and obese, black and white SA women, differences in TDEE were largely explained by ethnic differences in PAEE, and were not as a result of ethnic differences in REE.

Severely obese have greater LPS-stimulated TNF-alpha production than normal weight African-American women

Obesity is associated with an increase in chronic, low-grade inflammation which has been implicated in the development of type 2 diabetes mellitus and cardiovascular disease. The purpose of this study was to determine whether obesity was associated with an elevation of whole blood lipopolysaccharide (LPS)-stimulated tumor necrosis factor-alpha (TNF-alpha) production. African-American women were recruited from a larger study and assigned to one of five groups based on BMI: normal weight (NORM; BMI 20-25, n = 7), overweight (OVER; BMI 25-30, n = 12), class 1 obese (OB1; BMI 30-35, n = 19), class 2 obese (OB2; BMI 35-40, n = 10), or class 3 obese (OB3; BMI >40, n = 17). Body composition was determined via a whole body dual-energy X-ray absorptiometry (DXA) scan. Venous blood samples were collected following an overnight fast (>8 h), and stimulated with five doses of LPS (Salmonella enteriditis): 80, 40, 20, 10, and 5 microg/ml for 24 h in a 37 degrees C, 5% CO(2) incubator. Following stimulation, TNF-alpha was measured using enzyme-linked immunosorbent assay. OB3 produced 365% more TNF-alpha than NORM at an LPS dose of 20 microg/ml (P < 0.05). When maximal TNF-alpha production was assessed regardless of LPS dose, OB3 produced 230% more than NORM and OVER produced 190% more than NW (P = 0.001). Total and trunk fat mass and BMI were significantly correlated with maximal TNF-alpha production and LPS = 20 microg/ml. Our findings are consistent with previous reports suggesting a relationship between increased adiposity and inflammatory marker production. This is one of the first studies to focus on African-American women, who have higher rates of obesity.

The atypical presentation of the metabolic syndrome components in black African women: the relationship with insulin resistance and the influence of regional adipose tissue distribution

The appropriateness of the metabolic syndrome criteria as an indicator of cardiovascular disease risk has been challenged in black Africans. Hence, the aims of this study were (1) to examine the level of agreement between the International Diabetes Federation (IDF) and the National Cholesterol Education Program Adult Treatment Panel III (ATP III) metabolic syndrome criteria, which differ in their emphasis on central obesity; (2) to investigate the degree to which these criteria predict insulin resistance, as estimated by the homeostasis model assessment of insulin resistance (HOMA-IR); and (3) to investigate the extent to which a diagnosis of the metabolic syndrome and insulin resistance may be explained by body fat and its distribution. In 103 normal-weight (body mass index <or=25 kg/m(2), mean: 22.0 +/- 1.8 kg/m(2)) and 119 obese (body mass index >or=30 kg/m(2), mean: 33.9 +/- 5.5 kg/m(2)) urbanized black South African women (27 +/- 7 years old), body composition (dual-energy x-ray absorptiometry), fat distribution (waist and computed tomography), blood pressure, fasting glucose, HOMA-IR, and lipid profiles were measured. Insulin resistance was defined as the upper tertile of HOMA-IR. The overall proportion of individuals who met the IDF and ATP III metabolic syndrome criteria were 13% and 10%, respectively. Agreement was high between the IDF and ATP III metabolic syndrome criteria (kappa = 0.87); however, neither criteria predicted HOMA-IR (kappa = 0.16, 95% confidence interval: 0.05-0.27 and 0.14, 95% confidence interval: 0.05-0.27, respectively). Visceral adipose tissue was the largest contributor to diagnosis of the metabolic syndrome, and waist alone (>80 cm or >88 cm) had an improved specificity (21% or 18% higher, respectively) and positive predictive value (64% or 57% higher, respectively) for identifying insulin resistance compared with the metabolic syndrome criteria. Waist circumference was a better predictor of HOMA-IR than the IDF or ATP III metabolic syndrome criteria in young black African women without known disease. The measurement of waist circumference, as an indicator of disease risk, should therefore be encouraged in the public health setting.

Target population for clinical trials on sarcopenia

The term "sarcopenia" describes the progressive decline of muscle mass, strength and function occurring with aging. It is not considered a disease, but the direct consequence of the aging process on the skeletal muscle. Multiple demographic (e.g. gender, race), biological (e.g. inflammatory status) and clinical (e.g. diabetes, metabolic syndrome, congestive heart failure, medications) factors are able to influence (positively or negatively) the skeletal muscle quality and quantity. The extreme paucity of clinical trials on sarcopenia in literature is mainly due to difficulties in designing studies able to isolate the aging process from its multiple and interconnected consequences. In the present review, we present the major factors to consider as potential sources of biased results when evaluating potential candidates for clinical trials on sarcopenia. The development of clinical trials exploring the nature of the sarcopenia process is urgent, but several controversial issues on this hallmark of aging still need clarification.

Determinants of insulin-resistant phenotypes in normal-weight and obese Black African women

OBJECTIVE

Subsets of metabolically "healthy obese" and "at-risk" normal-weight individuals have been previously identified. The aim of this study was to explore the determinants of these phenotypes in black South African (SA) women.

METHODS AND PROCEDURES

From a total of 103 normal-weight (BMI <or= 25 kg/m(2)) and 122 obese (BMI >or= 30 kg/m(2)) black SA women, body composition, fat distribution, blood pressure, fasting glucose levels, insulin resistance, and lipid profiles were measured. Questionnaires relating to family history, physical activity energy expenditure (PAEE), and socio-demographic variables were administered. The subjects were classified as insulin sensitive or insulin resistant according to the homeostasis model assessment of insulin resistance (HOMA-IR) (>or=1.95 insulin resistant).

RESULTS

Our study showed that 22% of the normal-weight women were insulin resistant and 38% of the obese women were insulin sensitive. Increased visceral adipose tissue (VAT) (P=0.001) and decreased VAT/leg fat mass (P <or= 0.001), independent of total body fatness, distinguished between the phenotypes. Moreover, the insulin-sensitive women were of higher socioeconomic status, did more leisure and vigorous PAEE and were less likely to use injectable contraceptives. Using a regression model, body fat distribution, percent body fat, age, log leisure PAEE, and use of injected contraception accounted for 35% of the variance in HOMA-IR in the normal-weight women. In the obese women, 34% of the variance in HOMA-IR was explained by the same variables, excluding PAEE. No differences in smoking status or family history of metabolic disease were found between the phenotypes.

DISCUSSION

Central fat distribution, total adiposity, socioeconomic status, leisure PAEE, and use of injectable contraceptives distinguished between insulin-sensitive and insulin-resistant black SA women.

Impact of body mass index on incident hypertension and diabetes in Chinese Asians, American Whites, and American Blacks: the People's Republic of China Study and the Atherosclerosis Risk in Communities Study

Researchers have hypothesized that the impact of body mass index on chronic disease may be greater in Asians than in Whites; however, most studies are cross-sectional and have no White comparison group. The authors compared the associations with body mass index in Chinese Asians (n = 5,980), American Whites (n = 10,776), and American Blacks (n = 3,582) using prospective data from the People's Republic of China Study (1983-1994) and the Atherosclerosis Risk in Communities Study (1987-1998). Slopes of risk differences over body mass index levels were compared among the three ethnic groups in adjusted analyses. The authors found larger associations with body mass index in Chinese Asians compared with American Whites and Blacks for hypertension (p < 0.05). The increase in the incidence of hypertension associated with a one-unit increase in body mass index over approximately 8 years of follow-up was 2.5, 1.7, and 1.8 percentage points for Chinese Asians, American Whites, and American Blacks, respectively. For diabetes, the estimates were 1.7, 1.1, and 1.6 percentage points for the same groups- higher in Chinese Asians than in American Whites (p < 0.05) but similar between Chinese Asians and American Blacks. Given the ethnic differences in associations, the results support advocacy of public health and medical actions toward obesity prevention and treatment in China.

Diet and cardiovascular risk in university marching band, dance team and cheer squad members: a cross-sectional study

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in the United States. Diets high in fat, especially saturated fat, are often linked to obesity, hypertension and hypercholesterolemia, all risk factors for CVD. The purpose of this study was to determine the association between diet and CVD risk factors in members of a university marching band, dance team and cheer squad.

METHODS

In 2004, 232 marching band, dance team and cheer squad members completed a self-administered survey evaluating dietary intake. Body mass index (BMI), waist-to-hip ratio (WHR), blood pressure, fasting serum glucose and cholesterol were measured. Unpaired t-test and Pearson's chi square test were used to determine baseline differences by gender. Multiple linear regression analysis was used to determine the cross-sectional association between dietary intake of various food groups such as grains, meats, fruits & vegetables, dairy, water, alcohol and risk factors for CVD namely BMI, WHR, blood glucose, total cholesterol, and blood pressure (BP).

RESULTS

45% of the participants were overweight; 30% of females and 4.3% of males had WHR >/= 0.80 and 0.95 respectively. Almost 8% were hyperglycemic, 10% hypercholesterolemic, 15% had high systolic and 9% had high diastolic BP. Less than 50% consumed the recommended servings of grains, fruits and vegetables, dairy and water and 58% consumed alcohol. Higher grains intake was positively associated with higher BMI (Adjusted beta = 1.97, p = 0.030, 95% CI: 0.19, 3.74) and; higher alcohol intake was also positively associated with higher BMI (Adjusted beta = 0.15, p = 0.002, 95% CI: 0.06, 0.24).

CONCLUSION

These results warrant the evaluation of existing college-based health programs and development of new interventions to improve dietary habits and promote a healthy lifestyle in these athletes.