Anthropometric protocols for the construction of new international fetal and newborn growth standards: the INTERGROWTH-21st Project.

The primary aim of the INTERGROWTH-21(st) Project is to construct new, prescriptive standards describing optimal fetal and preterm postnatal growth. The anthropometric measurements include the head circumference, recumbent length and weight of the infants, and the stature and weight of the parents. In such a large, international, multicentre project, it is critical that all study sites follow standardised protocols to ensure maximal validity of the growth and nutrition indicators used. This paper describes, in detail, the selection of anthropometric personnel, equipment, and measurement and calibration protocols used to construct the new standards. Implementing these protocols at each study site ensures that the anthropometric data are of the highest quality to construct the international standards.

Anthropometric standardisation and quality control protocols for the construction of new, international, fetal and newborn growth standards: the INTERGROWTH-21st Project.

The primary aim of the INTERGROWTH-21(st) Project is to construct new, prescriptive standards describing optimal fetal and preterm postnatal growth. The anthropometric measurements include the head circumference, recumbent length and weight of the infants, and the stature and weight of the parents. In such a large, international, multicentre project, it is critical that all study sites follow standardised protocols to ensure maximal validity of the growth and nutrition indicators used. This paper describes in detail the anthropometric training, standardisation and quality control procedures used to collect data for these new standards. The initial standardisation session was in Nairobi, Kenya, using newborns, which was followed by similar sessions in the eight participating study sites in Brazil, China, India, Italy, Kenya, Oman, UK and USA. The intraobserver and inter-observer technical error of measurement values for head circumference range from 0.3 to 0.4 cm, and for recumbent length from 0.3 to 0.5 cm. These standardisation protocols implemented at each study site worldwide ensure that the anthropometric data collected are of the highest quality to construct international growth standards.

Frailty consensus: a call to action.

Frailty is a clinical state in which there is an increase in an individual's vulnerability for developing increased dependency and/or mortality when exposed to a stressor. Frailty can occur as the result of a range of diseases and medical conditions. A consensus group consisting of delegates from 6 major international, European, and US societies created 4 major consensus points on a specific form of frailty: physical frailty. 1. Physical frailty is an important medical syndrome. The group defined physical frailty as "a medical syndrome with multiple causes and contributors that is characterized by diminished strength, endurance, and reduced physiologic function that increases an individual's vulnerability for developing increased dependency and/or death." 2. Physical frailty can potentially be prevented or treated with specific modalities, such as exercise, protein-calorie supplementation, vitamin D, and reduction of polypharmacy. 3. Simple, rapid screening tests have been developed and validated, such as the simple FRAIL scale, to allow physicians to objectively recognize frail persons. 4. For the purposes of optimally managing individuals with physical frailty, all persons older than 70 years and all individuals with significant weight loss (>5%) due to chronic disease should be screened for frailty.

Longitudinal changes in calcaneal quantitative ultrasound measures during childhood.

UNLABELLED: This longitudinal study examined how calcaneal quantitative ultrasound (QUS) measures change during childhood while taking into account skeletal maturation, body mass index (BMI), and physical activity. The study reported sex differences in QUS growth curves and an inverse relationship between BMI and speed of sound (SOS) measures. INTRODUCTION: The aim of this study was to examine how calcaneal QUS parameters change over time during childhood and to determine what factors influence these changes. METHODS: The study sample consisted of a total of 192 Caucasian children participating in the Fels Longitudinal Study. A total of 548 calcaneal broadband ultrasound attenuation (BUA) and SOS observations were obtained between the ages of 7.6 and 18 years. The best fitting growth curves were determined using statistical methods for linear mixed effect models. RESULTS: There are significant sex differences in the pattern of change in QUS parameters (p < 0.05). The relationship between QUS measures and skeletal age is best described by a cubic growth curve in boys and a linear pattern among girls. Boys experience their most rapid growth in BUA and SOS in early and late adolescence, while girls experience constant growth throughout childhood. Adiposity levels were significantly associated with the changes in SOS among boys (p < 0.001) and girls (p < 0.01), indicating that children with higher BMI are likely to have lower SOS over time compared to children with lower BMI. For girls, physical activity levels showed positive associations with changes in QUS measures (p < 0.05). CONCLUSION: This study documents significant sex differences in the pattern of change in QUS measures over childhood and adolescence. Our study also shows significant influences of adiposity and physical activity on the pattern of change in QUS measures during childhood.

Left ventricular mass, abdominal circumference and age: the Fels longitudinal study.

PURPOSE: To determine the relationship of abdominal circumference with increased left ventricular mass (LVM) from young adulthood into old age. METHODS: Cross-sectional echocardiographic images were taken from 182 men and 220 women in the Fels Longitudinal Study 20 to 75 years of age to determine left ventricular mass. Left ventricular mass was divided by stature raised to the power of 2.7 (LVM/ht2.7) in order to minimize the impact of heart size variation from body size without overcompensating for the adverse effect of obesity. Abdominal circumference was measured and BMI calculated from stature and weight and categories of overweight, obesity and abdominal obesity were determined using published cut points. Regression models were used to describe the relationships of age, abdominal circumference, BMI and self-reported physical activity to LVM/ht2.7. RESULTS: Age, abdominal circumference and BMI were each positively and significantly related to an increased LVM/ht2.7 in men and women (p < 0.05). In the men, multivariate models indicated that abdominal circumference and BMI were both significantly related to an increased LVM/ht2.7, but the inclusion of BMI in these models for the women reduced the association of abdominal circumference and physical activity below significant levels. In the men, there was also a quadratic association of abdominal circumference with LVM/ht2.7 that was significant along with BMI and physical activity. Sex-specific logistic regressions with BMI and abdominal circumference obesity categories did not change or improve the initial findings in men or women. CONCLUSIONS: In women, increases in abdominal fatness as reflected in abdominal circumference at any age are linearly related to an increase in LVM/ht2.7, but the relationship of overall fatness as reflected in BMI with LVM/ht2.7 is stronger. In men, both abdominal fatness and overall fatness at any age are linearly related to an increase LVM/ht2.7. However, the significant curvilinear association of abdominal circumference and a linear association of BMI and physical activity with LVM/ht2.7 indicate the possible positive covariate relationship of overall muscle mass with LVM/ht2.7. This reflects the physiological changes with age and demonstrate, in part, the complexity of the interpretations of the inter associations of body composition, the cardiovascular system and the aging process, but the impact among the elderly and the known inadequacy of BMI at these ages remains an area for continued clinical study.

Sex differences in young adulthood metabolic syndrome and physical activity: the Fels longitudinal study.

OBJECTIVE: To evaluate the effects of habitual physical activity (PA) on the metabolic syndrome (MS) in young adult men and women. RESEARCH METHODS AND PROCEDURES: Cross-sectional PA data were utilized from 249 women and 237 men, aged 18-40 years in the Fels Longitudinal Study. MS components--abdominal circumference (AC), triglycerides (TG), HDL, blood pressure (BP), and fasting glucose (FG)--were dichotomized according to the National Cholesterol Education Program's Adult Treatment Panel III revised criteria. Leisure, sport, work, and total PA scores were calculated using the Baecke Questionnaire of Habitual Physical Activity. Multiple logistic regression modeling assessed the effects of PA, age, smoking, and BMI on MS status. RESULTS: 26.9% of men and 19.3% of women had MS. For men, MS risk was reduced with increases in both total PA [OR = 0.65 (95% CI: 0.47, 0.90)] and sport PA [OR = 0.40 (95% CI: 0.23, 0.70)]. AC, TG, and HDL values also improved with total and sport PA. Among women, the risk for MS was marginally reduced by total PA [OR = 0.72 (95% CI: 0.50, 1.02)] and HDL levels were increased by both total PA [OR = 0.79 (95% CI: 0.63, 0.98)] and sport PA [OR = 0.54 (95% CI: 0.35, 0.84)]. DISCUSSION: Increased total and sport PA reduces risk for the MS in young men, though not as clearly in young women.

Validity of a new automated software program for visceral adipose tissue estimation.

INTRODUCTION: Given the considerable time and research cost of analyzing biomedical images to quantify adipose tissue volumes, automated image analysis methods are highly desirable. Hippo Fat is a new software program designed to automatically quantify adipose tissue areas from magnetic resonance images without user inputs. Hippo Fat has yet to be independently validated against commonly used image analysis software programs. OBJECTIVE: Our aim was to compare estimates of VAT (visceral adipose tissue) and SAT (subcutaneous adipose tissue) using the new Hippo Fat software against those from a widely used, validated, computer-assisted manual method (slice-O-matic version 4.2, Tomovision, Montreal, CA, USA) to assess its potential utility for large-scale studies. METHODS: A Siemens Magnetom Vision 1.5-T whole-body scanner and a T1-weighted fast-spin echo pulse sequence were used to collect multiple, contiguous axial images of the abdomen from a sample of 40 healthy adults (20 men) aged 18-77 years of age, with mean body mass index of 29 kg/m(2) (range=19-43 kg/m(2)). RESULTS: Hippo Fat provided estimates of VAT and SAT that were highly correlated with estimates using slice-O-matic (R (2)>0.9). Average VAT was 9.4% lower and average SAT was 3.7% higher using Hippo Fat compared to slice-O-matic; the overestimation of SAT tended to be greater among individuals with greater adiposity. Individual-level differences for VAT were also substantial; Hippo Fattrade mark gave estimates of VAT ranging from 1184 cm(3) less to 566 cm(3) more than estimates for the same person using slice-O-matic. CONCLUSION: Hippo Fat provides a rapid method of quantifying total VAT, although the method does not provide estimates that are interchangeable with slice-O-matic at either the group (mean) or individual level.

Is the MNA valid in different populations and across practice settings?

OBJECTIVE: The MNA is a successful screening tool in geriatric medicine, but this success is in Europe or countries with Western health care practice settings. The MNA is not directly applicable in many ethnic groups or countries or those with non-Western cultural and dietary habits or health care systems. There is an increased prevalence of type 2 diabetes, the metabolic syndrome and obesity among the elderly; however, the MNA does not include questions or measures related to these or other important health conditions affected by nutritional status. This paper addresses the relevance of anthropometry and the impact of different clinical practice settings on the MNA and discusses the development of the Chinese Nutritional Screen (CNS) in China. CONCLUSIONS: If the MNA is to continue to be successful among groups of elderly around the world, then the MNA, CNS or similar instruments should be as country or culturally and ethnically specific as possible. The development of the CNS maintained the underlying assumptions and concept of the MNA but modified them for a country with diverse food and cultural habits and health care settings.

Unique and common genetic effects between bone mineral density and calcaneal quantitative ultrasound measures: the Fels Longitudinal Study.

INTRODUCTION: Areal bone mineral density (BMD) and calcaneal quantitative ultrasound (QUS) measures are correlated, and both traits predict osteoporotic fracture risk independently. However, few studies have examined whether common genetic effects (i.e., pleiotropy) exist between these traits in extended families. In this study, we estimated the additive genetic correlation and random environmental correlation between BMD measured at various skeletal sites and calcaneal QUS measures. METHODS: Our sample included 537 adults (251 men and 286 women) from 110 families participating in the Fels Longitudinal Study. Total hip, femoral neck, lumbar spine, and total body BMD were measured using dual energy X-ray absorptiometry. Three measures of calcaneal structure--broadband ultrasound attenuation (BUA), speed of sound (SOS), and quantitative ultrasound index (QUI)--were collected from the non-dominant heel using the Sahara sonometer. Applying a variance components-based maximum likelihood method, we estimated the heritability of each trait and estimated the genetic and environmental correlations between the different BMD and QUS measures. RESULTS: Heritability estimates were significant for all measures of BMD and QUS ranging from 0.55 to 0.78. Significant non-zero genetic correlations were found between the different BMD and QUS measures. All genetic correlations were also significantly different from 1. Genetic correlations between total hip BMD and each of the QUS measures were 0.63 with BUA, 0.50 with SOS, and 0.56 with QUI. For femoral neck BMD, genetic correlations were similar to those between total hip BMD and QUS measures. Genetic correlations between BMD of the lumbar spine and QUS measures ranged from 0.34 to 0.38, and those between total body BMD and QUS measures, from 0.51 to 0.54. In contrast, all random environmental correlations were not significantly different from zero. CONCLUSION: This study demonstrates that BMD and calcaneal QUS measures among healthy men and women are significantly heritable and are, in part, jointly influenced by a common set of underlying genes. Additionally, this study also provides evidence for a unique set of genes that independently influences each individual trait.

Lipids, lipoproteins, lifestyle, adiposity and fat-free mass during middle age: the Fels Longitudinal Study.

INTRODUCTION: Although lipid profiles tend to worsen with age, it is not fully known if such age-related changes are influenced primarily by body composition and lifestyle or by other aspects of aging. OBJECTIVE: We investigated the extent to which the fat and fat-free components of body mass index (BMI) and lifestyle factors influence patterns of change in lipids independent of age. DESIGN: Serial data were analyzed using sex-specific longitudinal models. These models use serial data from individuals to assume a general pattern of change over time, while allowing baseline age and the rate of change to vary among individuals. SUBJECTS: Serial data were obtained from 940 examinations of 269 healthy white participants (126 men, 143 women), aged 40-60 years, in the Fels Longitudinal Study. MEASUREMENTS: Measurements included age, the fat (FMI) and fat-free mass (FFMI) components of BMI, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), triglycerides (TG), total cholesterol (TC), fasting glucose and insulin, physical activity, alcohol use and smoking, and women's menopausal status and estrogen use. RESULTS: In both sexes, increased FMI was significantly associated with increased LDL-C, TG and TC, and decreased HDL-C. Increased FFMI was significantly related to decreased HDL-C and increased TG. Independent age effects remained significant only for LDL-C and TC in men and TC in women. Increased insulin was significantly related to increased TG in women. Moderate alcohol consumption was associated with higher HDL-C in men. Physical activity lowered male LDL-C and TC levels, and increased female HDL-C levels. Menopause was associated with increases in LDL-C. Premenopausal women not using estrogen had significantly lower HDL-C, TG, and TC than postmenopausal women taking estrogen. CONCLUSIONS: (1) Age is an important independent predictor for LDL-C and TC in men, and TC in women, but it is not as influential as body composition and lifestyle on HDL-C and TG in men and women, and LDL-C in women. (2) Increasing FMI is the major contributor to elevated TC, LDL-C and TG levels, and decreased HDL-C levels in men and women. (3) FFMI significantly influences HDL and TG levels in both sexes. (4) Maintaining a lower BMI via a reduced fat component may be more beneficial in lowering CVD risks than other factors.

Development of the Chinese nutrition screen (CNS) for use in institutional settings.

OBJECTIVES: To develop and validate a nutritional screening tool (CNS) for elderly Chinese subjects in the institutional setting. DESIGN: Using the MNA as a guide, a questionnaire was developed appropriate for the Chinese health care system, diet, food customs and culture, using physician assessment for comparison. PARTICIPANTS: 200 men and 200 women aged 65 years or older, approximately equally distributed by age between two cities in China (Hong Kong and Shanghai), were recruited from hospitals and old age homes for the reliability study. 340 men and 527 women were recruited for the validity study. RESULTS: The CNS compared with physician assessments based on two groups, normal or at risk with less than normal nutritional status, had kappa coefficients of 0.5 overall and were as high as 0.8 in Shanghai. CNS was able to identify about 90% of all persons with normal nutritional status and had about a 60% chance of correctly identifying a person at risk with a less than normal nutritional status. CONCLUSION: The CNS can be used in a 2-group classification to identify those who have a normal nutritional status (CNS > or = 21). Those who do not fall into this group should have their nutritional status evaluated in greater detail (CNS score < or = 20). The applicability of screening tools may vary depending on the site and the population characteristics.

Body composition estimates from NHANES III bioelectrical impedance data.

BACKGROUND: Body composition estimates for the US population are important in order to analyze trends in obesity, sarcopenia and other weight-related health conditions. National body composition estimates have not previously been available. OBJECTIVE: To use transformed bioelectrical impedance analysis (BIA) data in sex-specific, multicomponent model-derived prediction formulae, to estimate total body water (TBW), fat-free mass (FFM), total body fat (TBF), and percentage body fat (%BF) using a nationally representative sample of the US population. DESIGN: Anthropometric and BIA data were from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). Sex-specific BIA prediction equations developed for this study were applied to the NHANES data, and mean values for TBW, FFM, TBF and %BF were estimated for selected age, sex and racial-ethnic groups. RESULTS: Among the non-Hispanic white, non-Hispanic black, and Mexican-American participants aged 12-80 y examined in NHANES III, 15 912 had data available for weight, stature and BIA resistance measures. Males had higher mean TBW and FFM than did females, regardless of age or racial-ethnic status. Mean TBW and FFM increased from the adolescent years to mid-adulthood and declined in older adult age groups. Females had higher mean TBF and %BF estimates than males at each age group. Mean TBF also increased with older age groups to approximately 60 y of age after which it decreased. CONCLUSIONS: These mean body composition estimates for TBW, FFM, TBF and %BF based upon NHANES III BIA data provide a descriptive reference for non-Hispanic whites, non-Hispanic blacks and Mexican Americans in the US population.

Comparison of percent body fat estimates using air displacement plethysmography and hydrodensitometry in adults and children.

PURPOSE: The purpose of the study was to compare estimates of body density and percentage body fat from air displacement plethysmography (ADP) to those from hydrodensitometry (HD) in adults and children and to provide a review of similar recent studies. METHODS: Body density and percentage body fat (% BF) were assessed by ADP and HD on the same day in 87 adults aged 18-69 y (41 males and 46 females) and 39 children aged 8-17 y (19 males and 20 females). Differences between measured and predicted thoracic gas volumes determined during the ADP procedure and the resultant effects of those differences on body composition estimates were also compared. In a subset of 50 individuals (31 adults and 19 children), reliability of ADP was measured and the relative ease or difficulty of ADP and HD were probed with a questionnaire. RESULTS: The coefficient of reliability between %BF on day 1 and day 2 was 96.4 in adults and 90.1 in children, and the technical error of measurement of 1.6% in adults and 1.8% in children. Using a predicted rather than a measured thoracic gas volume did not significantly affect percentage body fat estimates in adults, but resulted in overestimates of percentage body fat in children. Mean percentage body fat from ADP was higher than percentage body fat from HD, although this was statistically significant only in adults (29.3 vs 27.7%, P<0.05). The 95% confidence interval of the between-method differences for all subjects was -7 to +9% body fat, and the root mean square error (r.m.s.e.) was approximately 4% body fat. In the subset of individuals who were asked to compare the two methods, 46 out of 50 (92%) indicated that they preferred the ADP to HD. CONCLUSION: ADP is a reliable method of measuring body composition that subjects found preferable to underwater weighing. However, as shown here and in most other studies, there are differences in percentage body fat estimates assessed by the two methods, perhaps related to body size, age or other factors, that are sufficient to preclude ADP from being used interchangeably with underwater weighing on an individual basis.

Assessing the body composition of 6-17-year-old Black and White girls in field studies.

The purpose of the study was to develop ethnic-specific equations for fat-free mass (FFM) from selected anthropometric dimensions and bioelectrical impedance measures of resistance (R) and reactance (Xc) for use in the NHLBI Growth and Heath Study. Using dual-energy X-ray absorptiometry measures of body composition as the dependent variable and field measures of body composition by anthropometry and bioelectrical impedance as the explanatory variables, ethnic-specific prediction equations were developed on a sample of girls representing a wide range of ages and BMI. The equations were cross-validated using (1) the Prediction of Sum of Squares (PRESS) statistic and (2) an independent sample of 20 girls of each race from a study conducted at the National Institute of Child Health and Human Development (NICHD). Subjects were 65 White and 61 Black girls 6-17 years of age. The best race-specific equations for FFM each explained 99% and 97% of the variance in the White and Black girls, respectively. Root mean square errors (RMSE) ranged from 1.14 to 1.95 kg. The equation for Black girls used Stature2/Resistance (R), weight, and reactance (Xc) as predictor variables; the equation for White girls used Stature2/R, weight, and triceps skinfold thickness. The results indicate that (1) equations to predict FFM in girls should be ethnic-specific and that (2) accurate values for TBF and %BF can be calculated from the predicted FFM.

Sex differences in bone mass acquisition during growth: the Fels Longitudinal Study.

Risk of osteoporosis in later life may be determined during adolescence and young adulthood. The present study used longitudinal data to examine the accumulation of bone mineral content (BMC) and bone mineral density (BMD) in Caucasian subjects ages 6-36 yr. Growth in BMC and BMD (measured by dual X-ray absorptiometry; Lunar, Madison, WI) of 94 males and 92 females was monitored for a mean period of 4.29 yr. The main findings were that there were no sex differences in BMC or BMD during the prepubertal stage; however, females had significantly higher BMD of the pelvis and BMC and BMD of the spine during puberty, and postpubertal males generally had significantly higher BMC and BMD than their female counterparts. In addition, the longitudinal rate of bone accumulation in both sexes increased rapidly during childhood and adolescence and was nearly complete at the end of puberty. Finally, peak BMC and BMD was achieved between the ages of 20 and 25 and occurred earlier in females than in males. The rates of growth and timing of peak bone mass as reported here define the crucial period during which intervention protocols should be developed for maximizing skeletal mass to prevent the development of osteoporosis.

Total body water reference values and prediction equations for adults.

BACKGROUND: The clinical interpretation of total body water (TBW) necessitates the availability of timely comparative reference data. The prediction of TBW volume in renal disease is critical in order to prescribe and monitor the dose of dialysis in the determination of Kt/V. In clinical practice, urea distribution (V) is commonly predicted from anthropometric equations that are several decades old and for white patients only. This article presents new reference values and prediction equations for TBW from anthropometry for white and black adults. METHODS: The study sample included four data sets, two from Ohio and one each from New Mexico and New York, for a total of 604 white men, 128 black men, 772 white women, and 191 black women who were 18 to 90 years of age. The TBW concentration was measured by the deuterium or tritium oxide dilution method, and body composition was measured with a Lunar DXA machine. An all-possible-subsets of regression was used to predict TBW. The accuracy of the selected equations was confirmed by cross-validation. RESULTS: Blacks had larger TBW means than whites at all age groups. The 75th TBW percentile for whites approximated the TBW median for blacks at most ages. The white men and black men and women had the largest TBW means ever reported for healthy individuals. The race- and sex-specific TBW prediction equations included age, weight, and stature, with body mass index (BMI) substituted for weight in the white men. The root mean square errors (RMSEs) and standard errors for the individual (SEIs) ranged from approximately 3.8 to 5.0 L for the men and from 3.3 to 3.6 L for the women. In both men and women, high values of TBW were associated with high levels of total body fat (TBF) and fat-free mass (FFM). CONCLUSION: : TBW in these healthy adults is relatively stable through a large portion of adulthood. There are significant race and sex differences in TBW. These accurate and precise equations for TBW provide a useful tool for the clinical prediction of TBW in renal disease for white and black adults. These are the first TBW prediction equations that are specific for blacks.

Health status of children with moderate to severe cerebral palsy.

The aim of the study was to evaluate the health of children with cerebral palsy (CP) using a global assessment of quality of life, condition-specific measures, and assessments of health care use. A multicenter population-based cross-sectional survey of 235 children, aged 2 to 18 years, with moderate to severe impairment, was carried out using Gross Motor Function Classification System (GMFCS) levels III (n = 56), IV (n = 55), and V (n = 122). This study group scored significantly below the mean on the Child Health Questionnaire (CHQ) for Pain, General Health, Physical Functioning, and Impact on Parents. These children used more medications than children without CP from a national sample. Fifty-nine children used feeding tubes. Children in GMFCS level V who used a feeding tube had the lowest estimate of mental age, required the most health care resources, used the most medications, had the most respiratory problems, and had the lowest Global Health scores. Children with the most severe motor disability who have feeding tubes are an especially frail group who require numerous health-related resources and treatments. Also, there is a relationship among measures of health status such as the CHQ, functional abilities, use of resources, and mental age, but each appears to measure different aspects of health and well-being and should be used in combination to reflect children's overall health status.

Evaluation of anthropometric equations to assess body-composition changes in young women.

BACKGROUND: Healthy young women who engage in an exercise program may lose fat that is not reflected in body weight changes because of concurrent gains in fat-free mass (FFM). OBJECTIVE: This study addressed the question of how well anthropometry-based predictive equations can resolve these changes. DESIGN: Several widely used skinfold-thickness- or circumference-based equations were compared by using dual-energy X-ray absorptiometry to study 150 healthy young women before and after 8 wk of Army basic combat training (average energy expenditure: 11.7 MJ/d). RESULTS: Women lost 1.2 +/- 2.6 kg fat (mean +/- SD) and gained 2.0 [corrected] +/- 1.5 kg FFM. Fat loss (r = 0.47), but not FFM gain (r = 0.01), correlated with initial fatness. Thus, for many women who lost fat, body weight did not change or increased. Fat loss was associated with a reduction in abdominal circumference but this alone was not a consistent marker of fat loss. One circumference equation and one skinfold-thickness equation yielded the smallest residual SDs (2.0% and 1.9% body fat, respectively) compared with the other equations in predicting body fat. The sensitivity and specificity of the best equations in predicting changes in percentage body fat were not better than 55% and 66%, respectively. CONCLUSIONS: These data suggest that for women, anthropometry can provide better estimates of fatness than body mass index but it is still relatively insensitive to short-term alterations in body composition. Not surprisingly, the circumference equation that includes the most labile sites of female fat deposition (ie, waist and hips instead of upper arm or thigh) proved to be the most reliable.

Childhood body composition in relation to body mass index.

OBJECTIVE: The aim is to describe body composition in relation to body mass index (BMI; body weight/stature(2)) to provide health care professionals insight into the meaning, significance, and limitations of BMI as an index of adiposity during childhood. METHODS: Data from 387 healthy, white children 8 to 18 years of age from the Fels Longitudinal Study were analyzed. Measurements were scheduled annually and each child was examined 1 to 11 times, totaling 1748 observations. Total body fat (TBF) and fat-free mass (FFM) were determined from hydrodensitometry. Stature and weight were measured using standard methods and BMI and the components of BMI, TBF/stature(2), and FFM/stature(2) were calculated. Analyses included correlations between BMI and body composition variables; age-related patterns of BMI, TBF/stature(2), and FFM/stature(2); and annual changes in BMI, TBF/stature(2), and FFM/stature(2). RESULTS: Generally, correlations between BMI and body composition variables were strong and significantly different from zero. Means for BMI throughout childhood were similar for boys and girls, although significantly larger values were observed for girls at ages 12 to 13 years. Age-related patterns of TBF/stature(2) and FFM/stature(2) differed between sexes. In each sex, annual increases in BMI were driven primarily by increases in FFM/stature(2) until late adolescence, with increases in TBF/stature(2) contributing to a larger proportion of the BMI increases in girls than in boys. CONCLUSIONS: Unlike adults, annual increases in BMI during childhood are generally attributed to the lean rather than to the fat component of BMI. Because the properties of BMI vary during childhood, health care professionals must consider factors such as age and sex when interpreting BMI.

Body mass index during childhood, adolescence and young adulthood in relation to adult overweight and adiposity: the Fels Longitudinal Study.

BACKGROUND: Childhood overweight develops during 'critical periods', but the relationship of body mass index (BMI) patterns during 'critical periods' from childhood into adulthood with subsequent overweight and adiposity has not been previously investigated. BMI patterns during early childhood, pubescence and post-pubescence and their independent effects on overweight and body fatness at 35-45 y of age were examined along with birth weight and the effects of adult lifestyle factors. METHODS: BMI parameters describing the timing, velocity minimum (min) and maximum (max) values from 2 to 25 y of age were related to adulthood BMI values and total and percentage body fat (TBF, %BF) at 35-45 y. These data were from 180 males and 158 females in the Fels Longitudinal Study. RESULTS: There was no sex difference in the timing of BMI rebound, but the age of BMI maximum velocity and maximum BMI were both earlier in girls. Children with an earlier BMI rebound had larger BMI values at rebound and at maximum velocity. Children who reached maximum BMI at later age had larger maximum BMI values. Maximum BMI was a strong predictor for adult BMI and in females, a strong predictor of adulthood TBF and %BF. Maximum BMI was closely related to maximum BMI velocity in females and in males, BMI at maximum velocity is a strong predictor of TBF and %BF. CONCLUSIONS: Changes in childhood BMI were related to adult overweight and adiposity more so in females than males. BMI rebound is a significant important period related to overweight at 35-45 y in females but not in males. However BMI patterns during and post-adolescence were more important than the BMI rebound for adulthood TBF and %BF status. There is marked tracking in BMI from approximately 20 y into 35-45 y. The pattern of BMI changes from 2 to 25 y had stronger effects on subsequent adult overweight than birth weight and adult lifestyle variables.