Relative Body Fat Content Research Articles

Estimation of Absolute and Relative Body Fat Content Using Noninvasive Surrogates: Can DXA Be Bypassed?

Dual-energy x-ray absorptiometry (DXA) scanning is used for objective determination of body composition, but instrumentation is expensive and not generally available in customary clinical practice. Anthropometric surrogates are often substituted as anticipated correlates of absolute and relative body fat content in the clinical management of obesity and its associated medical risks. DXA and anthropometric data from a cohort of 9230 randomly selected American subjects, available through the ongoing National Health and Nutrition Examination Survey, was used to evaluate combinations of surrogates (age, height, total weight, waist circumference) as predictors of DXA-determined absolute and relative body fat content. Multiple regression analysis yielded linear combinations of the 4 surrogates that were closely predictive of DXA-determined absolute fat content (R2 =0.93 and 0.96 for male and female subjects). Accuracy of the new algorithm was improved over customary surrogate-based predictors such as body mass index. However prediction of relative body fat was less robust (R2 less than0.75), probably due to the nonlinear relation between degree of obesity (based on body mass index) and relative body fat. The paradigm was validated using an independent cohort from the National Health and Nutrition Examination Survey, as well as two independent external subject groups. The described regression-based algorithm is likely to be a sufficiently accurate predictor of absolute body fat (but not relative body fat) to substitute for DXA scanning in many clinical situations. Further work is needed to assess algorithm validity for subgroups of individuals with "atypical" body construction.

The effect of confounding variables on the relationship between anthropometric and physiological features in 2000-m rowing ergometer performance.

Background: Anthropometric and physiological characteristics are often considered as potential variables that are significantly related with motor performance. Aim: The aim of this study was to identify and weigh the key anthropometric and physiological characteristics that are associated with 2000-m rowing ergometer performance in male and female athletes. Methods: The study involved 70 best female and 130 best male rowers from the seven largest Hungarian rowing clubs, classified into one of the following age categories: juniors (36 women and 55 men, age range: 15-16years), older juniors (26 women and 52 men, age range: 17-18years), and seniors (8 women and 23 men, age range: over 18years). Anthropometric and body composition measurements were determined by the bioelectrical impedance method proposed by Weiner and Lourie (1969), and skin fold measurements were conducted to estimate relative body fat content. The countermovement jump test and the 2000-m maximal rowing ergometer test were used for physiological measurements. Results: An increase in skeletal muscle mass was correlated (r = -.39, p <.001) with a significant decrease in rowing time over a distance of 2000m, whereas a significant increase in rowing time was noted with an increase in sitting height (only in men, r = .33, p <.001), body mass (in women and men: r = .24, p = .013 and r = .31, p = .009), and body fat percentage (r = .26, p < .030). Rowing time was also bound by a significant correlation with maximal force (r = -.79 and -.90, p <.001) and relative maximal power (r = -.54 and -.78, p <.001) in both sexes, with relative peak power in males (r = -.51, p < .001), and with estimated relative maximal aerobic capacity in females (r = -.43, p <.001). Conclusion: Rowing performance over a distance of 2000m is significantly negatively correlated with the skeletal muscle mass, maximal force, relative maximal power, relative peak power, and estimated relative maximal aerobic capacity.

Skeletal muscle mitochondrial uncoupling prevents diabetes but not obesity in NZO mice, a model for polygenic diabesity.

Induction of skeletal muscle (SM) mitochondrial stress by expression of uncoupling protein 1 (UCP1) in mice results in a healthy metabolic phenotype associated with increased secretion of FGF21 from SM. Here, we investigated whether SM mitochondrial uncoupling can compensate obesity and insulin resistance in the NZO mouse, a polygenic diabesity model. Male NZO mice were crossed with heterozygous UCP1 transgenic (tg) mice (mixed C57BL/6/CBA background) and further backcrossed to obtain F1 and N2 offspring with 50 and 75% NZO background, respectively. Male F1 and N2 progeny were fed a high-fat diet ad libitum for 20weeks from weaning. Blood glucose was reduced, and diabetes (severe hyperglycemia >300mg/dl) was fully prevented in both F1- and N2-tg progeny compared to a diabetes prevalence of 15% in F1 and 42% in N2 wild type. In contrast, relative body fat content and plasma insulin were decreased, and glucose tolerance was improved, in F1-tg only. Both F1 and N2-tg showed decreased lean body mass. Accordingly, induction of SM stress response including FGF21 expression and secretion was similar in both F1 and N2-tg mice. In white adipose tissue, expression of FGF21 target genes was enhanced in F1 and N2-tg mice, whereas lipid metabolism genes were induced in F1-tg only. There was no evidence for induction of browning in either UCP1 backcross. We conclude that SM mitochondrial uncoupling induces FGF21 expression and prevents diabetes in mice with a 50-75% NZO background independent of its effects on adipose tissue.

Physical Activity Levels of Hungarian Boys and Girls During 3 Weekdays and the Weekend

Antal et al. (2009) found that prevalence of overweight and obesity in Hungarian children was 18.1 and 7.4% for boys and 19.6 and 6.3% for girls. Little objective data has examined the physical activity (PA) levels of Hungarian children using accelerometry, and more data are needed concerning the habitual PA levels of school children. PURPOSE: To determinate the physical activity levels of children during 3 weekdays and weekend. METHODS: Sixty-three children (35 boys aged=11.5±1.1 yr and 28 girls aged=10.9±1.0 yr) from 2 schools returned signed informed parental consent and were invited to participate in the study. Physical activity was quantified using uni-axial accelerometry for 3 consecutive school days and 2 weekend days. The accelerometer was worn mounted on the right hip using a fitted elastic belt during all waking hours except for water-based activities. Epoch length was set at 5 seconds. Time spent in sedentary, light, moderate, and vigorous physical activity was determined using existing age- appropriate cut- points (Freedson at al. 1997). Children who did not achieve minimum 480 minute wear time/day were excluded from the statistical analysis. Differences in body dimensions between boys and girls were assessed using independent samples t-tests. Differences between means of daily activity were analysed by ANOVA. Statistical significance was set at p<0.05. RESULTS: Boys were significantly older than girls but their body dimensions, relative body fat content and body mass index was not different. Altogether only 9.5% of the investigated children were assessed overweight. Boys were consistently more active than girls but the differences were not significant on weekdays and on weekends. Hungarian children's moderate-to-vigorous physical activity was double the international 60 min./day recommendation on weekdays (boys=129.4±44.5 min, girls=116.±27.3min) and significantly decreased by Sunday (boys=90.3±44.8, girls=80.9±37.5) CONCLUSION: The differences were not significant which means that in boys and girls physical activity in weekdays, potentially as the children took part in the same PE lessons and afternoon school clubs. The organized daily routine on weekdays produced daily physical activity opportunities compared to the weekend.

Effects of two-month walking exercise on bone mass density in young, thin women

Effects of two-month walking exercise on bone mass density in young, thin women Study aim: To examine the effects of a walking programme on the bone mass density (BMD) in sedentary, thin women aimed at preventing bone losses. Material and methods: Twenty thin (BMI&lt;20) women aged 22.0 ± 1.5 years volunteered to participate in the study. They were randomly assigned into the exercise (n = 10) or control (n = 10) groups, those from the experimental group being submitted to a training programme lasting two months. The programme consisted of 3 walking sessions per week, 30 min each, at 50 - 75% of maximal heart rate. Anthropometric measurements, bone mass density (by DXA) at the hip and lumbar spine (L2 - L4) and oestradiol concentration in serum (by radioimmunoassay kits) in the follicular phase were made before and after the training programme. The same diet was maintained throughout the study and was monitored by 7-day recalls. Results: The walking programme induced significant increases in BMD (by 5.2% in the hip site, p&lt;0.001, and by 7.3% in the spine, p&lt;0.05). Significant decreases were found in calcium concentration in both groups (by about 5%) and in phosphorus concentration in the experimental group (by about 16%). In the experimental group also the relative body fat content significantly decreased (by 7.7%). Conclusion: Walking exercise practiced for two months reduced the risk of bone loss by significantly increasing bone density.

Effects of attending elevated level school physical education in 7 to 11-year-old boys

The aim of the present longitudinal study of four years was to analyse differences in growth patterns, age-related changes in body fat and physical performance in schoolchildren taking part either in normal or in elevated level physical education at school.Nine data collection sessions were carried out between 2002 and 2006 in 18 schools. The sample consisted of 521 non-athletic volunteer boys (PE=116, contrast = 405).The inter-group differences between mean height, body weight, body mass index, relative body fat content, mean scores in 30 m dash, 400 m run, and standing long jump as well as the patterns of change with age were analysed in this comparison. Between-observation differences were tested by repeated measures ANOVA. In case of a significant F-test Tukey's post-hoc tests were used. Age dependence was also studied by linear regression analysis.The between-group differences in mean height were not significant, but the slope of height increase with age was significantly greater in the PE boys. The PE boys were significantly lighter through all the nine observations and the slope of age-related weight increase was statistically faster in the group of contrast subjects. Both the BMI means and percent body fat means were consistently and significantly greater in the contrast group and faster increases were found in the group of the less active boys. The mean physical performances of the PE boys were consistently and significantly better. Their slopes of increase were statistically different.

Effects of indoor cycling associated with diet on body composition and serum lipids

Effects of indoor cycling associated with diet on body composition and serum lipids Study aim: To determine the effects of indoor cycling training combined with restricted diet, lasting 12 weeks, on serum lipid concentrations in obese women. Material and methods: Twenty women aged 23.8 ± 3.6 years were randomly assigned into two groups: control (C) and experimental (E), the latter subjected to indoor cycling at various loads, 3 sessions weekly, every session lasting 45 min, combined with restricted diet (about 1200 kcal daily) for 12 weeks. The following variables were recorded: body height and mass, BMI, relative body fat content (from 7 skinfolds), fat-free mass, triglycerides, cholesterol and lipoproteins (HDL, LDL, VLDL). Results: Significant increase in HDL and significant decreases in all other variables (except body height) were noted only in the experimental group. Conclusions: Indoor cycling associated with restricted diet is an excellent option in controlling obesity and serum lipids.

Effects of 3 hours a week of physical activity on body fat and cardio-respiratory parameters in obese boys

The prevalence of overweight or fat children and adolescents has markedly increased in Hungary during the past three decades. Among the possible factors insufficient physical activity and a relative or absolute excess of calorie intake associated to it can be regarded as the most important ones. The aim of the study was to analyse the effects of a 20-week aerobic exercise on body composition and on the exercise tested cardio-respiratory functions in 10-year-old obese boys. Obesity was defined by a BMI greater than the cut-off value reported by Cole and co-workers (5) and a relative body fat content above 30% (13). Of the study group 21 volunteer children completed the program; the contrast group contained 28 obese boys. Mean calendar age was 10.03 +/- 0.26 in the study group (S) and 9.88 +/- 0.29 in the control group (C). The members of group S had two curricular physical education (PE) classes a week and three extracurricular aerobic physical activity sessions of 60 min net time in the afternoon, on Mondays (swimming and water games), Wednesdays (folk dance) and Fridays (soccer). Group C had only 2 PE classes a week. Anthropometric and spiroergometric data were collected in the middle of January and June of 2004. Relative body fat content and BMI did not increase during the observation period in contrast to the significant increase of both in the control group. Peak minute ventilation, aerobic power, oxygen pulse, and running distance (performed on a treadmill) increased in group S, and did not change in group C. The program was considered successful despite that the changes in the observed physiological and physical indicators appeared to be slight. However, the 5-month elevated level of physical activity brought about such development in the physical status of the obese subjects that might be an appropriate basis for regular training. Fortunately, the cardio-respiratory functions of the investigated boys were not affected yet by obesity, consequently the really dramatic change in their further lifestyle exclusively depends on their decision.

Overweight and obesity in 7 to 10-year-old Hungarian boys

Increasing prevalence of overweight and obesity is a serious social and health problem both in the economically developed and developing countries. Despite this fact the nation-wide growth studies completed in Hungary during the past 30 years had not categorised the children either by body fat content or nutritional status. The aim of the study was to estimate the prevalence of overweight and obese boys in the country at the beginning of the new millennium. Height, body mass and four skinfold thicknesses were measured in 7173 volunteer boys aged between 7 and 10 and living in various urban and rural settlements of Hungary between 2003 and 2005. Nutritional status was qualified by the BMI and relative body fat content. The significantly increasing prevalence with age of overweight and obesity ranged between 10.3 and 23.4%. The results showed the joint effects of a secular trend of growth and of a remarkably changed lifestyle. Of these the consequences of the lifestyle are the more important ones. The high and possibly further increasing prevalence of child-age overweight and obesity reminds one of the observations of Kopp and associates (5), namely that of the increased prevalence of chronic childhood diseases during the past 15 years. More intense habitual physical activity and dramatic changes in dietary habits still promise some solution. No one should reckon, however, with the efficiency of physical education at the schools with its very few classes.

Changes over Four Years in Body Composition and Oxygen Uptake of Young Adult Males after University Graduation

Lifestyle changes and challenges following university graduation often present a sharp contrast to the relatively free and basically pleasant university life enjoyed by the typical college student. Adaptation to a new work environment, relocation to a new community, concerns of marriage and family, personal finances, including income and budgeting (automobile and mortgage payments, savings, etc.), and adjustment to independent living result in an unfamiliar schedule of duties, often too sedentary in nature. The aim of this study was to analyse the changes observed in young working professionals by comparing selected body composition estimates, and physiological working capacity variables at the time of university graduation and four years later. Anthropometric and functional cardio-respiratory exercise test data were collected in 26 physically active (but non-athletic) volunteer males at the time of their university graduation in 2000 and 4 years later in 2004. By the end of this four-year period body weight, body mass index (BMI), the sum of 5 skinfold thicknesses, and relative body fat content increased significantly. Both mean BMI and weight-related body fat content were within the categorized risk range at the time of the second data collection. Parallel with unfavourable changes in body composition, peak minute ventilation, aerobic power, oxygen pulse, and maximum treadmill running distance had decreased significantly during this time. We attributed the significant changes observed mainly to the dramatically changed lifestyle. The subjects could not maintain their previous level of habitual physical activity.

Aussage des Harnstoffverteilungsraumes zum Körperfettgehalt der Milchkuh

Abstract. Title of the paper: Utilization of urea space for estimation of body fat content in dairy cow The urea space 12 minutes after intravenous administration of a defined amount of urea (HVR12) is unsuitable for estimation of body fat content in dairy cows. There is no connection between the absolute body fat content and the absolute HVR12. Between the relative body fat content and the relative HVRI2 combined a low significant measure of accuracy is established. Bibliographical references about unsatisfactory results by use of this method particulary in lactating cows are confirmed.

Disruption of the relationship between fat content and leptin levels with aging in humans.

Leptin released from adipose tissue is believed to participate in a negative feedback loop regulating appetite, and malfunction of this mechanism could lead to obesity. We measured plasma leptin and body composition (dual energy x-ray absorptiometry) in 70 healthy subjects, divided into 3 age groups (young, 25 +/- 1 yr; middle-aged, 53 +/- 1 yr; old, 70 +/- 1 yr), while on a 5-day weight-maintaining diet. Pairwise correlations were assessed using product-moment correlation, and regression analysis was used to evaluate relationships between leptin and other variables. Leptin concentrations and relative body fat content were correlated in young females (r = 0.71; P = 0.009) and in young males (r = 0.76; P = 0.007), but not in the combined middle-aged and elderly groups (r = 0.19; P = 0.36 and r = 0.19; P = 0.38 in females and males, respectively). Regression analysis showed a clear correlation between circulating leptin and relative fat mass in the young subjects (P = 0.0001), but not in the older subjects (P = 0.199). We conclude that body fat content in young subjects correlates with plasma leptin in both genders, whereas this relationship is disrupted in elderly subjects, thus possibly contributing to the obesity occurring with age.

Role of prolactin and the gonads in seasonal physiological changes in the collared lemming (Dicrostonyx groenlandicus)

On a seasonal basis, collared lemmings undergo a number of physiological and morphological changes. Short photoperiod exposure results in a molt to a white pelage, an increase in body weight, a reduction in relative body fat content, an increase in relative water content, and the development of a bifid claw. Treatment with the dopamine agonist, CB-154, resulted in a reduction in serum prolactin and the development of the white pelage in lemmings housed under 16L:8D, while treatment with the dopamine antagonist, sulpiride, prevented the winter molt in animals transferred to 8L:16D. Castration under 16L:8D resulted in an increase in body weight and an enlargement of the bifid claw. Castrated animals also molted more readily when treated with CB-154 and developed a relatively greater carcass water content. Treatment with CB-154 increased relative carcass fat content. These findings suggest that, in the collared lemming, seasonal changes in pelage parameters are regulated by prolactin, with gonadal hormones playing a modulating role. Body weight, water content, and bifid claw size appear to be influenced by gonadal hormones.

Factors affecting food efficiency and body composition of growing ruminants offered straw-based diets: supplementation with lipids with and without protein meal

ABSTRACTGrowing heifers (experiment 1) and wether lambs (experiments 2 and 3) were offered ammoniated cereal straw with or without a protein meal. The effects of supplementation with long-chain fatty acids (LCFA; as calcium salts of LCFA (CaLCFA) or fat prills) on nutrient utilization were studied.Intake of the basal diet (g/kg live weight) was unaffected by the protein meal, but was often reduced by supplementation with LCFA, especially fat prills. Live-weight gain was increased both by supplementation with protein meal and CaLCFA. Fat prills only increased live-weight gain in the presence of protein meal and depressed live-weight gain in the absence of protein meal. There were small differences between the two sources of LCFA in their apparent effects on rumen fermentation.Supplementation with protein meal increased relative protein content (P &lt; 0·05) and tended to increase water content (P &gt; 0·05) in the wethers in experiment 3 (corrected to equal empty-body weight at slaughter). Of the LCFA, only CaLCFA tended to increase relative body fat content (by proportionately 0·23; (P &gt; 0·05) but decreased relative protein and water content by 0·05 and 0·06 (P &lt; 0·05).Supplementation of straw-based diets with as little as 20 g CaLCFA per kg food dry matter improved live-weight gain and efficiency of nutrient utilization of ruminants, particularly when offered in combination with a protein meal. There appeared to be marked differences in the effects of CaLCFA and fat prills on food intake, productivity and to some extent body composition.

Body composition of light and heavy rats in a high or low fat diet group

The authors studied the body composition of light and heavy male Wistar rats (approximately 11 and 21 weeks of age) from two diet groups fed a high-fat (HFD, 50 per cent (w/w) fat) and a low-fat diet (LFD, 3 per cent (w/w) fat), respectively. In both age-groups the heavy HFD rats showed a considerably higher fat proportion (as compared with light LFD rats) associated with a correspondingly reduced body water content and an approximately identical body protein concentration. On comparing light and heavy rats (11 and 21 weeks of age) from the same diet group as to their body composition, the authors found greater differences only in the 21-week-old HFD animals; as against light animals, the heavy animals exhibited a highly significant increase in body fat content and a highly significant decrease in body water content. A comparison of LFD and HFD animals of approximately the same weight revealed an increase of the relative body fat content and a decrease of the percentage of body water content in light 11-week-old and also in 21-week-old HFD animals as against heavy LFD animals.