Does menarche mark a period of elevated resting metabolic rate?

Resting metabolic rate (RMR) and body composition were measured in 44 initially nonoverweight girls at three time points relative to menarche: premenarche (Tanner stage 1 or 2), menarche (+/-6 mo), and 4 yr after menarche. Mean absolute RMR was 1,167, 1,418, and 1,347 kcal/day, respectively. Absolute RMR was statistically significantly higher at menarche than at 4 yr after menarche despite statistically significantly less fat-free mass (FFM) and fat mass (FM), suggesting an elevation in RMR around the time of menarche. The pattern of change in RMR, adjusted for FFM, log transformed FM, age, race, parental overweight, and two interactions (visit by parental overweight, parental overweight by FFM), was also considered. Adjusted RMR did not differ statistically between the visits for girls with two normal-weight parents. For girls with at least one overweight parent, adjusted RMR was statistically significantly lower 4 yr after menarche than at premenarche or menarche. Thus parental overweight may influence changes that occur in RMR during adolescence in girls.     

Correlates and predictors of the age of menarche

In a cross-sectional study of 452 girls between 10 and 16 years of age 36 indices of physical and 50 of mental development were tested for their correlation with age at menarche and chronological age, as well as for their predictive power for estimating menarche by multiple regression analysis. Indices of physical maturity and body weight when adjusted for chronological age showed the highest partial correlation coefficients with age at menarche. Among mental characters which show lower intercorrelations with menarche occurred the highest correlation coefficients for a handmotor factor "Spurennachzeichnen" and a factor "Gruppenabh?ngigkeit" (which indicates a type of social motivation). In general physical and mental factors correlate higher with chronological age than with age at menarche. By multiple regression analysis we determined 14 physical and 25 mental predictors explaining 21% and 17% respectively of the variance of age at menarche. The error of the estimate predicting menarche on body weight without knowledge of onset of menarche is +/- 1 year. Using chronological age in a sample of girls before menarche the error of the estimate only is +/- 6 months. To compare the predictive power of chronological age combined with body weight or with skeletal age the time interval is calculated within which 95% of girls attain menarche. The range of prediction extends from 4.3 to 1 year on chronological age (11-16 years); using mean body weight it can be improved by 1.8 to 6 months, while using mean skeletal age an improvement of 0.2 to 3.9 months is possible compared with body weight. The correlations between age at menarche and physical and mental variables are attributed to a common hormonal influence on rate of development.     

Size and shape modifications in Sardinian adolescent girls

In females, menarche is the defining moment of puberty, the period of life when the greatest body changes occur. In the present study, the metric and morphological variations associated with sexual maturation are defined in 155 Sardinian girls (10-17 years) and the role of some potentially influential variables is discussed: age, age at menarche and time since menarche. We studied thirty-eight anthropometric variables, the fat-free mass and the fat mass estimated by Bioelectrical Impedance Analysis. Statistical analyses were performed to evaluate the difference between pre- and post-menarcheal girls of the same age (Student's t-test) and to evaluate the different role played by the variables (principal components analysis, cluster analysis, multiple regression). The results demonstrate that the body dimensions of the adolescent girls mainly increase in concomitance with sexual maturation. The age at menarche influences the fat mass but not the distribution of visceral and subcutaneous fat. The time since menarche has also no effect on the distribution of subcutaneous fat.     

Bone mineral density is inversely related to parathyroid hormone in adolescent girls.

Preventive programs aimed at maximizing peak bone mass as a way of reducing the risk of osteoporotic fractures later in life should take into account the contribution of nutritional factors to bone mass accumulation in young age. The role of calcium and energy intakes on radial mineral density was investigated in 200 healthy girls (aged 11-15 yr) simultaneously evaluating serum changes of insulin-like growth factor-I (IGF-I), parathyroid hormone (PTH) and osteocalcin (OC). Dietary calcium and energy intakes were assessed by a 3-day food record method, bone mineral density (BMD) was performed at ultradistal (ud) and proximal (pr) radial sites using dual energy X-ray absorptiometry. Calcium consumption below the levels suggested by Dietary Reference Intakes in more than 80% of population studied was not related to BMD, which in turn markedly increased in post-compared to premenarcheal girls. Interestingly, in a multiple regression analysis PTH was inversely related to BMD after adjustment for calcium intake, bone age and menarche. Serum IGF-I was positively associated to energy intakes and bone age in girls before menarche, who exhibited the highest values of OC. Our data highlighted the role of food habits in modulating some hormonal response that might influence bone mineral apposition during adolescent age. Low calcium consumption associated to enhanced PTH values, if persisting, could be responsible for reduced rate of gain in bone mineral density. Thus, to optimize bone mineralization during the critical period of rapid body growth adequate intakes of calcium and energy should be recommended.     

Body composition characteristics during puberty in girls and boys from Eastern Austria

Puberty represents the final stage of sexual differentiation during which time the individual acquires reproductive capacity. Puberty is not only characterized by maturation of sexual organs and the formation of oocytes and mature spermatozoa, but also by the development of secondary sexual dimorphism. In industrialized countries the age of puberty has decreased steadily over the last 150 years in association with improved socio-economic conditions. However, the decreased onset of puberty is, especially in the female sex, associated with problematic changes in behaviour such as early onset of sexual activity and resulting in high risk teenage pregnancies. First of all, the improved nutritional status during childhood is discussed as a major cause for the decrease of puberty onset, whereas the impact of nutritional status especially on female sexual maturity is discussed controversially. In our study we analysed the association between body composition (fat tissue and fat free body mass, estimated by BIA analyses), height, Body Mass Index and fat distribution, and signs of puberty such as the timing of menarche in 228 girls and voice breaking and facial hair growth in 191 boys ageing between 10 and 15 years. In both sexes signs of puberty were highly significantly associated with body composition parameters. Nevertheless, marked differences between the two sexes were observed: Female puberty was positively associated first of all with weight status and the absolute and relative amount of body fat, while in signs of male puberty were related positively with a higher amount of fat free body mass and a decreased fat mass. Male voice breaking was significantly associated with increased stature, body weight, waist and hip circumference, lean body mass and total body water, in contrast voice breaking was significantly negatively associated with the fat percentage, the total fat mass and the waist to hip ratio. Female menarche was significantly positively associated with increased body weight, weight status, waist and hip circumference but also with increased absolute and relative fat mass, relative hip circumference, lean body mass and total body water. Only the waist to hip ratio was significantly negatively associated with the onset of menarche.     

Increased bone mineral density and serum leptin in non-obese girls with precocious pubarche: relation to low birthweight and hyperinsulinism.

BACKGROUND: Hyperinsulinism and hyperandrogenism have the capacity to increase bone mineral density (BMD) and serum leptin, independently of body fat mass. We therefore assessed lumbar BMD and serum leptin in girls with the sequence of a low birthweight and precocious pubarche (PP) in childhood, in whom hyperinsulinism and hyperandrogenism have been described. METHODS: Fifty-two non-obese PP girls were studied (age range 6.9-14.9 years). Serum leptin was also measured in 42 control girls, matched for age, body mass index and pubertal stage. RESULTS: BMD SDS, measured by dual-energy X-ray absorptiometry, was elevated in PP girls compared to the population reference (0.39 +/- 0.18 SDS; p = 0.03) and bone age, assessed from hand radiographs, was significantly advanced compared to chronological age (1.2 +/- 0.1 years; p < 0.0005). CONCLUSION: Compared to control girls, PP girls had higher leptin levels for degree of body mass index (PP girls: 9.4 +/- 0.6 ng/ml; controls: 7.8 +/- 0.6 ng/ml; p = 0.01). In PP girls, serum leptin was inversely related to birthweight (r = -0.32, p = 0.01) and positively related to free androgen index (FAI) (r = 0.71, p < 0.0005). BMD SDS was also inversely related to birthweight (r = -0.26, p < 0.05) and positively related to serum leptin (r = 0.42, p < 0.05), FAI (r = 0.45, p < 0.05) and mean serum insulin during oral glucose tolerance testing (MSI) (r = 0.59, p < 0.0005). In multiple regression, MSI was the strongest determinant of BMD SDS (beta = 0.50, p = 0.002). In conclusion, elevated BMD and serum leptin in non-obese PP girls were related to degrees of low birthweight, hyperinsulinism and hyperandrogenism. The characteristic hyperinsulinism of PP girls is proposed to be the key variable in this constellation.     

Body Composition Characteristics During Puberty in Girls and Boys from Eastern Austria

Puberty represents the final stage of sexual differentiation when the individual acquires reproductive capacity. Puberty is not only characterized by maturation of sexual organs and the formation of oocytes and mature spermatozoa, but also by the development of secondary sexual dimorphism. In industrialized countries, the age of puberty has decreased steadily over the last 150 years in association with improved socio-economic conditions. However, the decreased onset of puberty, especially in females, is associated with problematic changes in behaviour such as early onset of sexual activity resulting in high-risk teenage pregnancies. In our study, we analysed the association between body composition (fat tissue and fat-free body mass, estimated by BIA analyses), height, body mass index and fat distribution and signs of puberty such as the timing of menarche in 228 girls and voice breaking and facial hair growth in 191 boys ageing between 10 and 15 years. In both sexes, signs of puberty were associated, highly significantly, with body composition parameters. Nevertheless, marked differences between the two sexes were observed: Female puberty was positively associated with weight status and the absolute and relative amount of body fat, while in males, puberty was positively related with a higher amount of fat-free body mass and a decreased fat mass. Male voice breaking was significantly associated with increased stature, body weight, waist and hip circumference, lean body mass and total body water. In contrast, voice breaking was significantly negatively associated with the fat percentage, the total fat mass and the waist-to-hip ratio. Female menarche was significantly positively associated with increased body weight, weight status, waist and hip circumference and also with increased absolute and relative fat mass, relative hip circumference, lean body mass and total body water. Only the waist-to-hip ratio was significantly negatively associated with the onset of menarche.     

Age at menarche in urban Argentinian girls: association with biological and socioeconomic factors

Age at menarche is regarded as a sensitive indicator of physical, biological, and psychosocial environment. The aim of this study was to determine the age at menarche and its association with biological and socioeconomic factors in girls from Santa Rosa (La Pampa, Argentina). An observational cross-sectional study was carried out on 1,221 schoolgirls aged 9-15 years. Menarche data were obtained by the status-quo method. Height, sitting height, weight, arm circumference, tricipital and subscapular skinfolds were measured. We also calculated body mass index, measures of body composition and proportions, and fat distribution. To assess socioeconomic factors, parents completed a self-administered questionnaire about their occupation and education, family size, household, and other family characteristics. The median age at menarche - estimated by the logit method--was 12.84 years (95% CI: 12.71, 12.97). Compared with their premenarcheal age peers, postmenarcheal girls had greater anthropometric dimensions through age 12. After this age, only height was higher in the latter group. Data were processed by fitting two logistic regressions, both including age. The first model included anthropometric variables and birth weight, while the second model included the socioeconomic variables. The significant variables derived from each model were incorporated into a new regression: height, sitting height ratio (first model), and maternal education (second model). These three variables remained significantly associated with menarche. The results suggest a relationship between linear growth and menarche and agree with those found in other populations where the advancement of menarche is associated with improved living conditions. In relatively uniform urban contexts, maternal education may be a good proxy for the standard of living.     

Age at menarche in Iceland

The purpose of this study was to elucidate the mean age at menarche in Icelandic girls and compare it with results from other Scandinavian populations as well as in other ethnic groups. The study was performed during the school year 1972-1973 on a cross-sectional sample of 682 girls (aged 8.5 to over 17 years), constituting 9.5% of the girls from the third to eleventh forms in all the primary and secondary schools of Reykjavik. The mean age at menarche in Iceland, elicited by the status quo method, proved to be 13.06 +/- 0.10 years (S.D. 1.17 years). According to the information given by the girls (recall method), the earliest time of menstruation was 9.83 years and the latest 15.17 years, at which age all but one of the girls were menstruating.     

Menarcheal age of Turkish girls in Bremen

Several studies have shown that there is a Northwest-Southeast gradient in menarcheal age of European girls, with menarche occurring on the average about one year earlier in girls living in the Southern parts of Europe as compared with those from the Northern and Northwestern European countries. Eveleth & Tanner (1976) as well as Danker-Hopfe (1986a) suggested that this gradient is due primarily to genetic differences rather than climatic or nutritional variation. To substantiate this hypothesis menarcheal age of Turkish girls who lived in Bremen for several years has been investigated. The mean age at menarche estimated by probit analysis based on status quo data from n = 494 girls aged from 9.0 to 16.5 years was 12.90 +/- 1.21 years. These results correspond very well to those reported by Neyzi et al. (1975) for girls from Istanbul. On the other hand mean menarcheal age of Turkish girls living in Bremen is distinctly lower than mean age at menarche of urban German girls, living in the same district. In summary the results of the present study support the hypothesis of a predominantly genetic cause for the observed Northwest-Southeast gradient in age at menarche in Europe.     

Weight stability masks sarcopenia in elderly men and women

Skeletal muscle loss or sarcopenia in aging has been suggested in cross-sectional studies but has not been shown in elderly subjects using appropriate measurement techniques combined with a longitudinal study design. Longitudinal skeletal muscle mass changes after age 60 yr were investigated in independently living, healthy men (n = 24) and women (n = 54; mean age 73 yr) with a mean +/- SD follow-up time of 4.7 +/- 2.3 yr. Measurements included regional skeletal muscle mass, four additional lean components (fat-free body mass, body cell mass, total body water, and bone mineral), and total body fat. Total appendicular skeletal muscle (TSM) mass decreased in men (-0.8 +/- 1.2 kg, P = 0.002), consisting of leg skeletal muscle (LSM) loss (-0.7 +/- 0.8 kg, P = 0.001) and a trend toward loss of arm skeletal muscle (ASM; -0.2 +/- 0.4 kg, P = 0.06). In women, TSM mass decreased (-0.4 +/- 1.2 kg, P = 0.006) and consisted of LSM loss (-0.3 +/- 0.8 kg, P = 0.005) and a tendency for a loss of ASM (-0.1 +/- 0.6 kg, P = 0.20). Multiple regression modeling indicates greater rates of LSM loss in men. Body weight in men at follow-up did not change significantly (-0.5 +/- 3.0 kg, P = 0.44) and fat mass increased (+1.2 +/- 2.4 kg, P = 0.03). Body weight and fat mass in women were nonsignificantly reduced (-0.8 +/- 3.9 kg, P = 0.15 and -0.8 +/- 3.5 kg, P = 0.12). These observations suggest that sarcopenia is a progressive process, particularly in elderly men, and occurs even in healthy independently living older adults who may not manifest weight loss.     

Synergy between thinness and intensive sports activity in delaying menarche.

In a study to assess the effects of intensive physical activity and thinness on menarche records of 648 girls aged 10-14 were analysed. The girls were classified as thin or not thin on the basis of their body mass index, and whether or not they engaged in intensive sports activity was established. The presence of either thinness or intensive sports activity was associated with roughly a twofold decrease in the proportion of girls who had reached menarche; the presence of both factors was associated with roughly a fourfold decrease. These results did not appear to depend on age. Thus intensive sports activity and thinness appear to have a synergistic effect in delaying menarche.     

Relation of infant diet to childhood health: seven year follow up of cohort of children in Dundee infant feeding study.

OBJECTIVE: To investigate the relation of infant feeding practice to childhood respiratory illness, growth, body composition, and blood pressure. DESIGN: Follow up study of a cohort of children (mean age 7.3 years) who had detailed infant feeding and demographic data collected prospectively during the first two years of life. SETTING: Dundee. SUBJECTS: 674 infants, of whom 545 (81%) were available for study. Data on respiratory illness were available for 545 children (mean age 7.3 (range 6.1-9.9) years); height for 410 children; weight and body mass index for 412 children; body composition for 405 children; blood pressure for 301 children (mean age 7.2 (range 6.9-10.0) years). MAIN OUTCOME MEASURES: Respiratory illness, weight, height, body mass index, percentage body fat, and blood pressure in relation to duration of breast feeding and timing of introduction of solids. RESULTS: After adjustment for the significant confounding variables the estimated probability of ever having respiratory illness in children who received breast milk exclusively for at least 15 weeks was consistently lower (17.0% (95% confidence interval 15.9% to 18.1%) for exclusive breast feeding, 31.0% (26.8% to 35.2%) for partial breast feeding, and 32.2% (30.7% to 33.7%) for bottle feeding. Solid feeding before 15 weeks was associated with an increased probability of wheeze during childhood (21.0% (19.9% to 22.1%) v 9.7% (8.6% to 10.8%)). It was also associated with increased percentage body fat and weight in childhood (mean body fat 18.5% (18.2% to 18.8%) v 16.5% (16.0% to 17.0%); weight standard deviation score 0.02 (-0.02 to 0.06) v -0.09 (-0.16 to 0.02). Systolic blood pressure was raised significantly in children who were exclusively bottle fed compared with children who received breast milk (mean 94.2 (93.5 to 94.9) mm Hg v 90.7 (89.9 to 91.7) mm Hg). CONCLUSIONS: The probability of respiratory illness occurring at any time during childhood is significantly reduced if the child is fed exclusively breast milk for 15 weeks and no solid foods are introduced during this time. Breast feeding and the late introduction of solids may have a beneficial effect on childhood health and subsequent adult disease.     

Endocrine characteristics of adolescent menstrual cycles: impact of early menarche

An initial group of 200 girls, 7-17 years old, was investigated longitudinally 4 times at 1.5-, 1.5- and 5-year intervals. The present study gives information of the impact of early menarche, a risk factor for breast cancer, on some physical and endocrine characteristics in these subjects. The frequency of ovulation depended significantly on both the time since menarche and the age at menarche. Early menarche was associated with early onset of ovulatory cycles. Even in early puberty, before menarche, the subjects who displayed early menarche during follow-up had higher serum FSH and estradiol concentrations than the girls whose menarche took place after the age of 13.0 years. Adrenal androgen secretion (dehydroepiandrosterone) was not influenced by age at menarche but it increased, as expected, on the basis of chronological age. The group with early menarche was characterized by high circulating estradiol concentrations also after menarche, even in the oldest subjects so far studied, 17-25 years of chronological age. At these ages, the differences in the frequencies of ovulatory cycles were disappearing between the groups formed on the basis of age at menarche. The present findings in pre- and postmenarcheal subjects suggest that the increased risk of breast cancer associated with early menarche is created over several years of exposure to high-level estrogen stimulus.     

Plasma adiponectin concentration in healthy pre- and postmenopausal women: relationship with body composition, bone mineral, and metabolic variables

The aim of the current investigation was to determine the possible relationships of fasting adiponectin level with body composition, bone mineral, insulin sensitivity, leptin, and cardiorespiratory fitness parameters in 153 women. Subjects were classified as premenopausal (n = 42; 40.8 +/- 5.7 yr) if they had regular menstrual periods, early postmenopausal (n = 49; 56.7 +/- 3.6 yr) if they had been postmenopausal for more than >1 yr but <7 yr (5.5 +/- 1.3 yr), and postmenopausal (n = 62; 72.2 +/- 4.5 yr) if they had been postmenopausal for >7 yr. All women studied had a body mass index (BMI) <30 kg/m(2). Adiponectin values were higher (P < 0.05) in middle-aged (12.0 +/- 5.1 microg/ml) and older (15.3 +/- 7.3 microg/ml) postmenopausal women compared with middle-aged premenopausal women (8.4 +/- 3.2 microg/ml). Mean plasma adiponectin concentration in the total group of women (n = 153) was 12.2 +/- 6.3 microg/ml and was positively related (P < 0.05) to age, indexes of overall obesity (BMI, body fat mass), and cardiorespiratory fitness (PWC) values. In addition, a negative association (P < 0.05) between adiponectin with central obesity (waist-to-hip and waist-to-thigh ratio), fat-free mass, bone mineral (bone mineral content, total and lumbar spine bone mineral density), and leptin and insulin resistance (insulin, fasting insulin resistance index) values was observed. However, multivariate regression analysis revealed that only age, fasting insulin resistance index, and leptin were independent predictors of adiponectin concentration. In conclusion, circulating adiponectin concentrations increase with age in normal-weight middle-aged and older women. It appears that adiponectin is independently related to age, leptin, and insulin resistance values in women across the age span and menstrual status.     

Malnutrition, menarche, and marriage in rural Bangladesh

In order to assess the impact of nutritional status on the onset of menarche and the association between age at menarche and age at marriage, a survey of 1155 girls, ages 10 through 20, was conducted in a rural area of Bangladesh in March 1976. In order to obtain an estimated mean of age of menarche, probit analysis was used. The mean age of menarche using this technique is estimated at 15.65 for Muslims and 15.91 for Hindus. It was learned that in recent years the age of menarche has increased in a rural area. This increase seems to be associated with malnutrition caused by the war, postwar inflation, floods and famines during the 1971-75 period. When age is controlled for, the prominent effect of weight on menstrual status is evident. 98% of the girls whose weights were 88 pounds or greater had reached menarche compared to only 1% of those weighing less than 66 pounds. Body weight appears to be 1 of the most important factors for the determination of onset of menarche. There exists a seasonality of onset of menarche with a peak in winter. Age of marriage among this rural population has increased and may be associated with the increasing age of menarche. Since both age of menarche and age of marriage have increased, fertility among females age 15-19 may be expected to decrease in the future if this pattern continues.     

Mode of Infant Feeding and Achieved Growth in Adolescence: Early Feeding Patterns in Relation to Growth and Body Composition in Adolescence

TULLDAHL, JENNY, KJELL PETTERSSON, SUSAN W. ANDERSSON, AND LENA HULTHÉN. Mode of infant feeding and achieved growth in adolescence: Early feeding patterns in relation to growth and body composition in adolescence. Obes Res. Objective: Feeding mode in infancy and differences in childhood growth have been studied in several longitudinal studies, but few studies have followed children up to adolescent age. There is evidence that formula-fed infants weigh more and are taller than their breast-fed counterparts, and indications that this difference may sustain. Research Methods and Procedures: We have studied the relations between length of breast-feeding, growth, and body composition in a group of 781 representatively chosen adolescents. Data on feeding pattern in infancy and on weight and height from birth up to 18 years were collected. We studied the relation between high body mass index (BMI) (defined as ≤85^th percentile) in adolescence and length of breast-feeding. Results: Girls who were not breast-fed or breast-fed for less than 3 months had a significantly higher height curve than girls exclusively breast-fed for more then 3 months. There were tendencies towards higher values of adipose tissue measured by skinfolds in girls breast-fed for 3 months or less. Short duration of exclusive breast-feeding was associated with higher BMI (p<0. 04). In a subgroup of 194 adolescents, body composition was measured with dual energy X-ray. Both boys and girls who were exclusively breast-fed for more than 3 months were leaner and showed a trend towards lower skinfold values. Conclusion: These results are important to include in the debate about optimal feeding in infancy. Regarding breastfeeding as a standard, our results imply that formula fed infants may be at risk for overfeeding, which might lead to overweight, even up to adolescent age.     

Menopause in Blackfeet women--a life span perspective

A lifespan perspective, combining quantitative and qualitative approaches, is used to examine factors related to the timing of menopause in Blackfeet women of northern Montana (USA). Cross-sectional survey data demonstrate a median age at menopause using a status quo method of 51.6 years, and a mean age of 47.0 +/- 5.0 years among those women who had already experienced menopause. Age at menopause is inversely associated with age at menarche and having been breastfed, and positively associated with use of contraceptives, household income, and current or recent employment. Household income and age at menarche influence menopause age jointly in multivariate models. These and other patterns are examined in the lives of two women with very divergent ages at menopause. Although these data support an effect of early life influences on shaping reproductive trajectories that culminate in menopause, environmental factors and human agency during adult life may play a modifying role.     

Racial/ethnic differences in body fatness among children and adolescents

Background: Although the BMI is widely used as a measure of adiposity, it is a measure of excess weight, and its association with body fatness may differ across racial or ethnic groups. Objective: To determine whether differences in body fatness between white, black, Hispanic, and Asian children vary by BMI‐for‐age, and whether the accuracy of overweight (BMI‐for‐age ≥ Centers for Disease Control and Prevention (CDC) 95th percentile) as an indicator of excess adiposity varies by race/ethnicity. Methods and Procedures: Total body dual‐energy X‐ray absorptiometry (DXA) provided estimates of %body fat among 1,104 healthy 5‐ to 18‐year‐olds. Results: At equivalent levels of BMI‐for‐age, black children had less (mean, 3%) body fatness than white children, and Asian girls had slightly higher (1%) levels of %body fat than white girls. These differences, however, varied by BMI‐for‐age, with the excess body fatness of Asians evident only among relatively thin children. The ability of overweight to identify girls with excess body fatness also varied by race/ethnicity. Of the girls with excess body fatness, 89% (24/27) of black girls, but only 50% (8/16) of Asian girls, were overweight (P = 0.03). Furthermore, the proportion of overweight girls who had excess body fatness varied from 62% (8/13) among Asians to 100% (13/13) among whites. Discussion: There are racial or ethnic differences in body fatness among children, but these differences vary by BMI‐for‐age. If race/ethnicity differences in body fatness among adults also vary by BMI, it may be difficult to develop race‐specific BMI cut points to identify equivalent levels of %body fat.     

Relationship between change in BMI with age and delayed menarche in female athletes

Body mass index (BMI) is widely used as an index of obesity in people from the school age children to adults. However, the relationship between the change in BMI with age and the coming of menarche has not been discussed as there are few reports on the changes in BMI with age. In this study, the change in BMI with age was examined by applying the wavelet interpolation method (WIM), and a critical period for body fat in terms of the coming of menarche was estimated from the growth velocity. We investigated delayed menarche according to the influence of stress in athletes by comparing delayed menarche between athletes and non-athletes in relation to the critical period. Data were obtained from 144 female athletes in their first year at university in the Tokai area, all of whom had competed in a national sports competition in high school (athlete group). Health examination records showing these subjects' heights and weights from the first grade of elementary school to the final year of high school (1984-1995) were collected and BMI was calculated for each grade. Ages at menarche were ascertained from questionnaires. A control group of 73 non-athletes was similarly examined. The age at maximum peak velocity (MPV) derived from the growth (aging) distance curve of BMI was determined in the control group to be 11.96+/-0.97 years old. This age at MPV of BMI was almost the same as the age at menarche (12.11+/-0.93 years old). Therefore, this age at MPV of BMI is estimated to be the critical period of body fat for the coming of menarche. The interval between the age at MPV of BMI and age at menarche was 0.74+/-1.30 years in the athlete group and 0.15+/-0.81 years in the control group, so there was a significant difference (P<0.01) between the two groups. It is suggested that the delayed menarche in athletes is influenced by the stress of regular sports training.