Accuracy of body mass index (BMI) thresholds for predicting excess body fat in girls from five ethnicities.
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The association between body mass index (BMI) and body fat in young people differs among ethnic groups. Consequently, BMI thresholds for defining childhood overweight may not represent an equivalent level of adiposity in multiethnic populations. The objectives of this study were to characterise the relationships between BMI and percentage body fat (%BF) and to determine the appropriateness of universal BMI standards for predicting excess fatness in girls from five ethnic groups. The BMI and %BF of 1,676 European, Maori, Pacific Island, East Asian, and South Asian girls aged 5-16 years were determined using anthropometric and bioimpedance measurements. Receiver operating characteristic (ROC) curves were prepared to assess the sensitivity and specificity of the International Obesity Taskforce (IOTF) and Centers for Disease Control and Prevention (CDC) BMI thresholds for detecting %BF >85th percentile. Compared with European girls, South and East Asians averaged 4.2% and 1.3% more %BF at a fixed BMI and age, whereas Pacific Islanders averaged 1.8% less %BF. Areas under the ROC curves ranged from 89.9% to 92.4%, suggesting that BMI is an acceptable screening tool for identifying excess adiposity. However, the IOTF and CDC thresholds showed low sensitivity for predicting excess %BF in South and East Asian girls, with low specificity in Pacific Island and Maori girls. The development of an ethnic-specific definition of overweight improved diagnostic performance. We conclude that BMI can be an acceptable proxy measure of excess fatness in girls from diverse ethnicities, especially when ethnic-specific BMI reference points are implemented. (+info)
CRH-stimulated cortisol release and food intake in healthy, non-obese adults.
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Polymorphisms in serotonin-related genes in anorexia nervosa. The first study in Czech population and metaanalyses with previously performed studies.
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Anorexia nervosa is a serious psychiatric disorder characterized by the inability to maintain normal body weight. The frequently studied polymorphisms in the serotonin 5-HT2A receptor gene (-1438A/G) and in serotonin transporter 5-HTT gene (LPR, VNTR) have led to controversial results in different populations. The aim of the study was to address association of the above-mentioned polymorphisms with anorexia nervosa in the Czech population. We genotyped a well-defined group of 75 patients with anorexia nervosa (average age of 25.39 years, SD 6.18; average BMI 14.65 (SD 1.38)). The control group consisted of 65 Caucasian healthy females (average age 25.76 years, SD 5.12; average BMI 20.69, SD 1.85). The 5-HT2A receptor -1438A/G polymorphism analysis showed a trend for the association with odds ratios for risk allele A being in the same direction. In combination with a previously published Polish cohort, the allelic test reached a suggestive borderline (P = 0.0362, chi2 statistics, 1 df). In meta-analysis which included all published results for allelic tests, the resulting P value was highly significant (0.0003, chi2 statistics, 1 df). Using quantitative association of 5-HTR2A polymorphism with BMI in the Czech sample, a borderline association (P = 0.055) was observed. In 5-HTT, LPR polymorphism analysis, unlike in 5-HT2A, neither allelic nor quantitative association with BMI for the bi-allelic 5-HTT marker was observed. Results of this study support previous reports of a significant role of the A allele (-1438A/G, 5-HT2A receptor) as a risk factor in anorexia nervosa. (+info)
Nuts and healthy body weight maintenance mechanisms.
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Nuts are rich sources of multiple nutrients and phytochemicals associated with health benefits, including reduced cardiovascular disease risk. This has prompted recommendations to increase their consumption. However, they are also high in fat and are energy dense. The associations between these properties, positive energy balance and body weight raise questions about such recommendations. Numerous epidemiological and clinical studies show that nuts are not associated with weight gain. Mechanistic studies indicate this is largely attributable to the high satiety and low metabolizable energy (poor bioaccessibility leading to inefficient energy absorption) properties of nuts. Compensatory dietary responses account for 55-75% of the energy provided by nuts. Limited data suggest that routine nut consumption is associated with elevated resting energy expenditure and the thermogenic effect of feeding, resulting in dissipation of another portion of the energy they provide. Additionally, trials contrasting weight loss through regimens that include or exclude nuts indicate improved compliance and greater weight loss when nuts are permitted. Nuts may be included in the diet, in moderation, to enhance palatability, nutrient quality, and chronic disease risk reduction without compromising weight loss or maintenance. (+info)
Body fat-based weight norms for children and youths.
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INTRODUCTION: The issue of establishing reference values, especially of those pertaining to somatic features, is of importance for an assessment of normal growth. It was assumed that norms ought to reflect not the actually existing status but the recommended one. Thus, weight-height relations, including body mass index (BMI), ought to be established for that fraction of the general population, in which body fat content is within physiologically acceptable limits. THE AIM OF THE STUDY: To construct weight-to-height percentile norms for boys and girls aged 7-20 years. MATERIAL AND METHODS: A cohort of healthy boys (n=1282) and girls (n=1150) attending schools in the Eastern regions of Poland participated in the study. Their body height, body mass and body fat content were determined, the latter by skinfold (Slaughter's method) or bioimpedance measurements. The data for constructing normal values of body fat content were compiled from diverse sources so as to associate them smoothly with the normal values for adults. RESULTS: By applying the proposed lower and upper limits of body fat, 1007 boys (78.5%) and 581 girls (50.5%) with acceptable fat content were selected for constructing percentile norms of body mass expected for height, as well as for BMI. CONCLUSIONS: The existing norms for BMI of children and youths, also the Polish ones, differ from each other, as these were not based on data from subjects with acceptable body fat and assessing body fat content from BMI is known to be markedly biased. Unlike BMI, the presented percentile weight-for-height norms are age-independent in the range 7-20 years and are thus much easier to use. Those norms may be recommended as a tool in assessing the course of normal growth, as well as in developmental disorders and possible clinical intervention. (+info)
Weight-height relationship in girls with normal body fat content--Turner's syndrome vs. healthy short-statured.
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INTRODUCTION: Turner's syndrome is characterised by severely deficient body height and distorted body proportions as compared with healthy girls. It could be expected that shorter legs with respect to trunk length, together with a wider shoulder girdle, would disturb weight-height proportions. THE AIM OF THE STUDY: To compare weight-height relation in Turner girls with that in healthy, short-statured girls, provided both had body fat content within "normal" limits. MATERIAL AND METHODS: The study included 39 girls with Turner's syndrome and 63 healthy short-statured girls aged 10-20 years. Body height, body mass and body fat content were determined. Data analysis was performed for only those girls whose body fat content was within approximate normal limits for age calculated for the purpose of presented study. Body height and body mass were transformed to logarithms in order to obtain allometric relations. RESULTS: No significant differences were found between regression slopes what means that body mass was proportional to body height in both groups. On the other hand, regression constants differed significantly (p<0.001); Turner girls were, on average, by 11% heavier than their healthy mates. CONCLUSION: The selection of Turner and healthy, short-statured subjects with "normal" percentage of body fat content led to conclusion that increased relative body mass of Turner girls resulted from their specific body proportions and not from increased fat content. (+info)
Cognitive interference from food cues in weight loss maintainers, normal weight, and obese individuals.
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