Obesity in children and adolescents: relationship to growth, pubarche, menarche, and voice break

Maternal cafeteria diet influences kisspeptin (Kiss1), kisspeptin receptor(Gpr54), and sirtuin (Sirt1) genes, hormonal and metabolic profiles, and reproductive functions in rat offspring in a sex-specific manner†

Kisspeptin (KP, encoded by Kiss1, binding to the Gpr54 receptor) is a neuropeptide conveying information on the metabolic status to the hypothalamic-pituitary-gonadal axis. KP acts together with dynorphin A (encoded by Pdyn) and neurokinin B (encoded by Tac2) to regulate reproduction. KP is crucial for the onset of puberty and is under the control of sirtuin (encoded by Sirt1). We hypothesize that the maternal cafeteria (CAF) diet has adverse effects on the offspring's hormonal, metabolic, and reproductive functions due to sex-specific alterations in the expression of Kiss1, Gpr54, Pdyn, Tac2, and Sirt1 in the hypothalamus, and Kiss1, Gpr54, and Sirt1 in the liver. Rats were fed a CAF diet before pregnancy, during pregnancy, and during lactation. The vaginal opening was monitored. Offspring were sacrificed in three age points: PND 30, PND 35, and PND 60 (females) and PND 40, PND 45, and PND 60 (males). Their metabolic and hormonal status was assessed. mRNA for Kiss1, Gpr54, Pdyn, Tac2, and Sirt1 were measured by real-time PCR in the hypothalamus and/or livers. We found that CAF offspring had lower weight and altered body composition; increased cholesterol and triglyceride levels, sex-specific changes in glucose and insulin levels; sex-dependent changes in Sirt1/Kiss1 mRNA ratio in the hypothalamus; sex-specific alterations in Kiss1 and Sirt1 mRNA in the liver with more diversity in males; and a delayed puberty onset in females. We concluded that the mother's CAF diet leads to sex-specific alterations in metabolic and reproductive outcomes via Kiss1/Gpr54 and Sirt1 systems in offspring.

Associations of Obesity With Growth and Puberty in Children: A Cross-Sectional Study in Fuzhou, China

Objectives: To investigate the associations of obesity with growth and puberty in children. Methods: From November 2017 to December 2019, height, weight, and Tanner stages of 26,879 children aged 3-18 years in Fuzhou, China were assessed. Results: The obese group was significantly taller than the non-obese group after age 4 years for both genders, yet there was no significant difference in height between obese and non-obese group after 15.5 years old for boys and 12.5 years old for girls. The inflection points of significant growth deceleration in obese and non-obese groups were 14.4 and 14.6 years old for boys, and 11.8 and 12.8 years old for girls, respectively. The proportions of testicular development in boys with obesity and non-obesity were 7.96% and 5.08% at 8.5-8.9 years old, respectively, while the proportions of breast development in girls were 17.19% and 3.22% at age 7.5-7.9 years old, respectively. Conclusion: Children with obesity were taller in early childhood, earlier onset of puberty and earlier cessation of growth than children with non-obesity of the same age. However, there was sex dimorphism on the effect of obesity on the incidence of precocious puberty.

Insights into the implication of obesity in hypogonadism among adolescent boys

OBJECTIVES

This research aimed at uncovering the mechanisms behind obesity-related hypogonadism in adolescent boys and to investigate the association between anthropometric characteristics and testicular functions of these boys.

METHODS

This study included 60 adolescent boys (12-18 years) with exogenous obesity (BMI≥95th percentile) and 30 age matched lean controls (BMI=15th-85th percentile). Full clinical examination, anthropometric measurements and pubertal assessment were performed. Laboratory investigations included hemoglobin, hematocrit, lipid panel, LH, FSH, free and total testosterone, inhibin B and estradiol.

RESULTS

The results indicated the presence of positive family history of obesity in 85% of obese boys vs. 40% of the lean counterparts. Concerning SBP of obese boys, 7% were hypertensive (95th percentile), 25% were prehypertensive (between 90th and 95th percentiles) while, DBP findings showed that 33% are hypertensive and 33% are prehypertensive. Meanwhile, 13.3% of lean controls were prehypertensive. Anthropometric measurements and lipid profile values revealed a significant difference between obese and lean boys. Compared to obese boys the normal weight boys had higher levels of free testosterone (21.15 ± 2.90 pg/mL vs. 11.38 ± 3.96 pg/mL, p<0.001), total testosterone (10.59 ± 6.63 ng/dL vs. 3.23 ± 1.70 ng/dL, p<0.001), FSH (7.33 ± 3.75 mIU/mL vs. 5.63 ± 3.96 mIU/mL, p=0.026) and inhibin B (83.28 ± 27.66 pg/mL vs. 62.90 ± 17.85 pg/mL, p=0.001) and they registered lower level of estradiol (18.48 ± 7.33 pg/mL vs. 40.20 ± 7.91 pg/mL, p<0.001). In obese boys, BMI SDS significantly correlated with lipid profile and estradiol whereas, it showed significant negative correlation with LH, free and total testosterone and inhibin B. Penile length significantly correlated with LH while it revealed significant negative correlation with cholesterol.

CONCLUSIONS

This study evidenced a close association between obesity and hypogonadism in adolescent boys which could be due to the increased estradiol level and decreased T/E2 ratio.

Effects of childhood obesity and related genetic factors on precocious puberty: protocol for a multi-center prospective cohort study

BACKGROUND

Childhood obesity has important effects on the onset and development of puberty. Although a number of studies have confirmed the relationship between obesity and precocious puberty, little is known about the pleiotropic genes of obesity and precocious puberty and the interaction between genes and environment. There are four objectives: (1) to analyze the incidence of precocious puberty in the general population in China; (2) to verify the direct effect of obesity on children's precocious puberty using a variety of methods; (3) to verify the effect of obesity and its risk gene polymorphism on precocious puberty in a prospective cohort study; and (4) to analyze the interaction effect of genes and environment on pubertal development.

METHODS

We will conduct a multi-center prospective cohort study in three cities, which are selected in southern, central, and northern China, respectively. Primary schools in these cities will be selected by a stratified cluster random sampling method. Primary school students from grade 1 to grade 3 (6 to 10 years old) will be selected for the cohort with extensive baseline data collection, including assessment of pubertal development, family demographic information, early development, sleep pattern, dietary pattern, and physical activity. Participants will be followed up for at least three years, and long-term follow-up will depend on future funding.

DISCUSSION

The findings of this multicenter prospective population-based cohort study may expand previous related puberty development research as well as provide important information on the mechanism of early puberty. Targeted interventions can also be developed to improve adolescent health problems related to puberty development based on the available evidence.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04113070 , prospectively registered on October 2, 2019.

Growth and adrenarche: findings from the CATS observational study

BACKGROUND

There is increasing evidence that patterns of pubertal maturation are associated with different patterns of health risk. This study aimed to explore the associations between anthropometric measures and salivary androgen concentrations in pre-adolescent children.

METHODS

We analysed a stratified random sample (N=1151) of pupils aged 8-9 years old from 43 primary schools in Melbourne, Australia from the Childhood to Adolescence Transition Study. Saliva samples were assayed for dehydroepiandrosterone (DHEA), DHEA-sulfate and testosterone. Anthropometric measures included height, weight, body mass index (BMI) and waist circumference. Associations between (1) anthropometric measures and each androgen, and (2) hormone status with obesity and parental report of pubertal development were investigated using linear regression modelling with general estimating equations.

RESULTS

Greater height, weight, BMI and waist circumference were positively associated with higher androgen concentrations, after adjusting for sex and socioeconomic status. Being overweight or obese was associated with higher testosterone and DHEA concentrations compared with the normal BMI category. Those who were obese were more likely (OR=2.7, 95% CI 1.61 to 4.43, p<0.001) to be in the top tertile of age-adjusted androgen status in both sexes.

CONCLUSION

This study provides clear evidence for an association between obesity and higher androgen levels in mid-childhood. The adrenal transition may be a critical time period for weight management intervention strategies in order to manage the risk for metabolic problems in later life for high-risk individuals.

Trajectory of Body Mass Index from Ages 2 to 7 Years and Age at Peak Height Velocity in Boys and Girls

OBJECTIVE

To examine the associations between body mass index (BMI) at 2-4 years and 5-7 years and age at peak height velocity (APHV), an objective measure of pubertal timing, among boys and girls from predominantly racial minorities in the US that have been historically underrepresented in this research topic.

STUDY DESIGN

This study included 1296 mother-child dyads from the Boston Birth Cohort, a predominantly Black and low-income cohort enrolled at birth and followed prospectively during 1998-2018. The exposure was overweight or obesity, based on Centers for Disease Control and Prevention reference standards. The outcome was APHV, derived using a mixed effects growth curve model. Multiple regression was used to estimate the overweight or obesity-APHV association and control for confounders.

RESULTS

Obesity at 2-4 years was associated with earlier APHV in boys (B in years, -0.19; 95% CI, -0.35 to -0.03) and girls (B, -0.22; 95% CI, -0.37 to -0.07). Obesity at 5-7 years was associated with earlier APHV in boys (B, -0.18; 95% CI, -0.32 to -0.03), whereas overweight and obesity at 5-7 years were both associated with earlier APHV in girls (overweight: B, -0.24; 95% CI, -0.40 to -0.08; obesity: B, -0.27; 95% CI, -0.40 to -0.13). With BMI trajectory, boys with persistent overweight or obesity and girls with overweight or obesity at 5-7 years, irrespective of overweight or obesity status at 2-4 years, had earlier APHV.

CONCLUSIONS

This prospective birth cohort study found that overweight or obesity during 2-7 years was associated with earlier pubertal onset in both boys and girls. The BMI trajectory analyses further suggest that reversal of overweight or obesity may halt the progression toward early puberty.

Low BMI, but not high BMI, influences the timing of puberty in boys

BACKGROUND

Previous studies investigating the association between weight status and onset of puberty in boys have been equivocal. It is currently unclear to what extent weight class influences puberty onset and progression.

OBJECTIVES

To explore the relationship between degree of sexual maturation and anthropometric measures in Norwegian boys.

METHODS

The following endpoints were collected in a Norwegian cross-sectional study of 324 healthy boys aged 9-16: ultrasound-determined testicular volume (USTV), total serum testosterone, Tanner pubic hair stage, height, weight, waist circumference (WC), subscapular skinfolds (SSF), and body fat percentage (%BF). Testicular volume-for-age z-scores were used to classify "early," "average," or "late" maturing boys. Ordinal logistic regression analyses with a proportional odds model were applied to analyze the association between anthropometric variables and age-adjusted degree of pubertal development, with results expressed as age-adjusted odds ratios (AOR). Cumulative incidence curves for reaching pubertal milestones were stratified by BMI.

RESULTS

Boys with a low BMI for age (BMI_z  < -1) were less likely to have reached a pubertal testicular volume (USTV ≥ 2.7 mL) or a pubertal serum level of testosterone (≥0.5 nmol/L) compared to normal weight boys (AOR 0.3, p = 0.038, AOR 0.3, p = 0.026, respectively), and entered puberty on average with a delay of approximately eight months. Boys with high BMI for age (BMI_z  > 1) exhibited a comparable timing as normal weight boys. The same was found for WC. Pubertal markers were not associated with SSF or %BF.

CONCLUSION

By examining the association between puberty and weight status classified as low, average, or high, we found that a low BMI or WC for age were associated with a less advanced pubertal development and delayed timing of puberty in boys. No significant association was observed for a high BMI or WC. Moreover, no significant effects of SSF or %BF were observed. A low weight status should also be considered when assessing pubertal development in boys.

Voice break in boys-temporal relations with other pubertal milestones and likely causal effects of BMI

STUDY QUESTION

How is timing of voice break related to other male pubertal milestones as well as to BMI?

SUMMARY ANSWER

We provide a comprehensive temporal analysis of male pubertal milestones, including reproductive hormone dynamics, confirm voice break as a late milestone of male puberty and report a likely causal relationship between higher BMI and earlier age at voice break in men.

WHAT IS KNOWN ALREADY

Voice break represents a late pubertal milestone and recalled age at voice break is frequently used in epidemiological studies as a measure of puberty. In contrast, clinical studies use mainly testicular enlargement and/or genital tanner stage as the marker of pubertal onset. However, neither correlation of pubertal milestones nor reproductive hormone dynamics have been assessed in detail previously. Further, although BMI and puberty timing are known to be closely linked, cause and effect between these traits are not known.

STUDY DESIGN, SIZE, DURATION

The study included a population-based mixed cross-sectional and longitudinal cohort (2006–2014, COPENHAGEN Puberty Study) of 730 healthy Danish boys. Data for 55 871 male research participants from the 23andMe study were obtained, including genome-wide single nucleotide polymorphism data and age at voice break.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We performed a detailed evaluation of pubertal milestones and reproductive hormone levels (study population 1). A Mendelian randomization (MR) approach was used to determine the likely causal link between BMI and timing of voice break (study population 2).

MAIN RESULTS AND THE ROLE OF CHANCE

Voice break occurred at mean age 13.6 (95% CI: 13.5–13.8) years. At voice break, mean (95% CI) testosterone levels, LH levels and bi-testicular volume were 10.9 (10.0–11.7) nmol/L, 2.4 (2.2–2.5) IU/L and 24 (23–25) mL, respectively. Voice break correlated moderately strongly with timing of male pubertal milestones, including testicular enlargement, gonadarche, pubarche, sweat odor, axillary hair growth and testosterone above limit of detection (r² range: 0.43–0.61). Timing of all milestones was negatively associated with age-specific BMI (all P ≤ 0.001). MR analyses inferred likely causal effects of higher BMI on earlier voice break in males (−0.35 years/approximate SD, P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

Participation rate of the population-based cohort was 25%. Further, boys that were followed longitudinally were examined approximately every 6 months limiting the time resolution of pubertal milestones. Using adult BMI as exposure instead of prepubertal BMI in the MR analysis and the known inaccuracies of the testosterone immunoassay at low testosterone levels may be further limitations.

WIDER IMPLICATIONS OF THE FINDINGS

We provide valuable normative data on the temporal relation of male pubertal milestones. Further, the likely causal relationship between BMI and puberty timing highlights the importance of preventing obesity in childhood.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Danish Agency for Science, Technology and Innovation (09-067 180); Danish Ministry of the Environment, CeHoS (MST-621-00 065); Capital Region of Denmark (R129-A3966); Ministry of Higher Education and Science (DFF-1331-00 113); Innovation Fund Denmark (InnovationsFonden, 14-2013-4); The International Center for Research and Research Training in Endocrine Disrupting Effects of Male Reproduction and Child Health. B.H., F.R.D., J.R.B.P. and K.K.O. are supported by the Medical Research Council (MC_UU_12015/2). The 23andMe study is supported by the National Human Genome Research Institute of the National Institutes of Health (R44HG006981). Members of the 23andMe Research Team are employees of 23andMe, Inc. and hold stock or stock options in 23andMe.

TRIAL REGISTRATION NUMBER

NCT01411527

Common Genetic Influences on Age at Pubertal Voice Change and BMI in Male Twins

The present study aimed to explore secular trends in age at voice change (AVC), estimate heritability of AVC and investigate to what extent common genes influence the association between AVC and body mass index (BMI) in South Korean males. The sample of 955 male twins consisted of 241 pairs and 118 co-twin missing monozygotic (MZ) twins, 82 pairs and 50 co-twin missing dizygotic (DZ) twins and 141 male members of opposite-sex DZ twins who participated in telephone surveys in the South Korean Twin Registry. AVC was asked of twins during the surveys. The mean (SD) age of the sample was 18.92 (2.42) years (range: 16.00-29.25 years). The birth years of the twins were divided into two groups (1988-1993, 1994-2001). Kaplan-Meyer survival analyses were conducted to compute the mean age of AVC in the total sample as well as to test mean differences between the two birth cohorts. Maximum likelihood twin correlations and univariate and bivariate model-fitting analyses were performed. The mean AVC in the total sample was 14.19 (95% CI [14.09, 14.29]) years. The mean AVC significantly declined from 14.38 to 14.02 years from 1988 to 2001, confirming downward trends in AVC in recent years. Heritability for AVC was .59 (95% CI [.50, .67]), which was within the range reported in most Western twin studies. Although the phenotypic correlation between AVC and BMI was modest (r = -.14; 95% CI [-.07, -.21]), it was entirely mediated by common genes, similar to what has been found in females in prior twin studies. In conclusion, the present twin study underscores the importance of genetic influences on pubertal timing and its association with BMI in South Korean males.

Reduced pubertal growth in children with obesity regardless of pubertal timing

Childhood obesity affects both pubertal growth and pubertal timing. We evaluated pubertal timing-mediated effects of childhood obesity on pubertal growth. This retrospective, representative-population-based cohort study included 6,733 boys and 6,916 girls born between April 1975 and March 1976 in Akita Prefecture, Japan. Individual changes in height standard deviation score between 7 and 17 years (ΔHtSDS), body mass index Z-score at 7 years (BMIZ), and estimated age at peak height velocity (ÂPHV) were used as surrogate indicators of pubertal growth, childhood obesity and pubertal timing, respectively. ÂPHV-mediated effect of BMIZ on ΔHtSDS was evaluated, and non-ÂPHV-mediated effect was calculated. Based on BMIZ, participants were categorized into three groups (underweight, normal-weight and obese groups), and the differences in ΔHtSDS between obese and normal-weight or underweight groups and ratios of non-ÂPHV-mediated effect were determined. ΔHtSDS values in the obese group were lower by 1.23 in boys and 1.17 in girls than those in the underweight group and by 0.87 in boys and 0.85 in girls than those in the normal-weight group. Non-ÂPHV-mediated effect on the reduced ΔHtSDS in the obese group compared to the underweight and normal-weight groups accounted for 68% and 71% in boys and 59% and 64% in girls, respectively. Thus, childhood obesity is associated with reduced pubertal growth regardless of pubertal timing. This reduced pubertal growth observed in children with obesity could be more affected by non-pubertal timing-mediated effect rather than pubertal timing-mediated effect.

Effect of body mass index percentile on skeletal maturation of cervical vertebrae and hand-wrist and dental maturation

Objective: The aim of this study was to evaluate the relationship between age- and gender-specific body mass index (BMI) percentile and skeletal and dental maturation in Turkish adolescents.Materials and methods: A sample of 429 patients (171 males, 258 females aged between 7 and 17 years) was selected. Skeletal maturation was identified in the hand-wrist radiography by Björk, Grave and Brown (BGB), and the cervical vertebrae maturation (CVM) method defined by Hassel and Farman in lateral cephalometric radiography. Dental maturation was determined by the Demirjian method. BMI was calculated by reference curves used for Turkish children. A regression model was used for the relationship between BMI percentile and skeletal and dental maturation.Results: There was no significant correlation between BMI and skeletal maturation of cervical vertebrae and dental maturation. A one-percentile increase in BMI percentile accelerates the increase of period (likelihood of being post-pubertal period) to 1.016 times (p < .05). Skeletal maturation of hand-wrist and cervical vertebrae and dental maturation were more prominent in females compared to males (p < .05). Males and females were not statistically significantly different in BMI percentile (p = .52).Conclusions: BMI may be considered before deciding to estimate the skeletal and dental maturation in an individual by the relevant methods.

Obesity Is Associated with Earlier Pubertal Onset in Boys

CONTEXT

Pubertal timing in boys is associated with body mass index (BMI). Studies consistently report an inverse correlation of BMI and pubertal timing within the normal BMI range. However, observations in obese boys are conflicting with different studies reporting either early or delayed pubertal onset in obese boys.

OBJECTIVE

We aimed to assess the association of male pubertal timing with age-specific BMI (zBMI) in obese boys.

DESIGN, SETTING, AND PARTICIPANTS

A total of 218 obese boys (zBMI > +2SD, with a median age at baseline of 10.8 years (range 4.2-17.0), were recruited as part of a prospective outpatient childhood obesity intervention program at Nordsjællands Hospital, Hillerød, Denmark, between 2009 and 2017. Serving as controls, we included 660 healthy boys participating in the population-based COPENHAGEN Puberty Study (-2SD < zBMI ≤ +2SD, 2006-2014). Subanalyses were performed on overweight controls (+1SD < zBMI ≤ +2SD). The clinical assessment of pubertal development by Tanner staging, including testis volume using a Prader's orchidometer, was performed by trained physicians. The timing of pubertal milestones was estimated by probit analyses.

MAIN OUTCOME MEASURES

Timing of testicular volume ≥ 4 mL, genital stage ≥ 2, and pubarche.

RESULTS

The mean (95% confidence interval [CI]) age of onset of pubertal event in obese boys was as follows: testicular volume ≥ 4 mL, 11.3 years (11.0-11.6); genital stage ≥ 2, 11.6 yrs (11.3-11.9); and pubarche, 11.9 years (11.5-12.3). Testicular volume ≥ 4 mL occurred significantly earlier in obese boys compared to controls (-2SD < zBMI ≤ +2SD) (P = 0.01). We did not observe significant differences for either the timing of pubarche nor the genital stage ≥ 2 (P = 0.06 and P = 0.94, respectively).

CONCLUSIONS

We demonstrate that testicular enlargement in obese boys occurs significantly earlier compared to a population-based normal-weight reference cohort.

Onset and tempo of sexual maturation is differentially associated with gestational phthalate exposure between boys and girls in a Mexico City birth cohort

Phthalates are endocrine disrupting compounds commonly found in consumer products, exposure to which may influence reproductive maturation. Effects from exposure in utero on the onset and progression of sexual development are understudied. We examined longitudinal associations between gestational phthalate exposure and sexual maturation at two points in adolescence (8-14, 9-18 years). Gestational exposure was quantified using the geometric mean of 3 trimester-specific urinary phthalate metabolite measurements. Sexual maturation was assessed using Tanner stages and menarche onset for girls and Tanner stages and testicular volume for boys. Generalized estimating equations for correlated ordinal multinomial responses were used to model relationships between phthalates and odds of transitioning to the next Tanner stage, while generalized additive (GA) mixed models were used to assess the odds of menarche. All models were adjusted for child age (centered around the mean), BMI z-score, change in BMI between visits, time (years) between visits (ΔT), and interactions between ΔT and mean-centered child age and the natural log of exposure metabolite concentration. Among girls, a doubling of gestational MBzP concentrations was associated with increased odds of being at a higher Tanner stage for breast development at 8-14 years (OR = 4.62; 95% CI: 1.38, 15.5), but with slower progression of breast development over the follow-up period (OR = 0.65 per year; 95% CI: 0.46, 0.92) after adjustment for child age and BMI z-score. Similar results were found for ∑DEHP levels and breast development. In boys, a doubling of gestational MBP concentrations was associated with lower odds of being at a higher Tanner stage for pubic hair growth at 8-14 years (OR = 0.37; 95% CI: 0.14, 0.95) but with faster progression (OR: 1.28; 95% CI: 0.97, 1.69). These results indicate that gestational phthalate exposures may impact the onset and progression of sexual development, and that these relationships differ between boys and girls.

The Relationship Between Quality of Life and Pubertal Timing in Adolescence: The Toyama Birth Cohort Study, Japan

PURPOSE

Although pubertal timing is gradually becoming earlier in Japan, support as for physical and mental health among children experiencing earlier puberty than their peers is inadequate. To better understand health and life satisfaction in seventh grade students (age 12-13 years), examination of relationships between health outcomes and pubertal timing, socioeconomic status, and lifestyle factors is necessary.

METHODS

Participants of the Toyama Birth Cohort Study (4,752 males and 4,740 females) answered questions regarding school year of onset of voice break for boys and menarche for girls, sleep quality, mental health difficulties, overall health, quality of life (QOL), and lifestyle. Relationship between health outcomes and pubertal timing was examined using binary logistic regression analysis.

RESULTS

Earlier pubertal timing was associated with four health-related outcomes. For poor sleep quality, the adjusted odds ratio (OR) of fourth grade males and crude OR of fifth grade females were statistically significant. Regarding mental health difficulties, the crude OR of fifth grade males and adjusted OR of fourth, fifth, and sixth grade females were statistically significant. Associations between poor overall health and fourth grade males and fourth or fifth grade females were observed. For poor QOL, the adjusted OR of fourth grade males and females was statistically significant.

CONCLUSIONS

Relationships between earlier pubertal timing and poor sleep quality, mental health difficulties, poor physical health, and poor QOL were observed. To improve children's quality of life, support from teachers and school doctors and nurses is needed-especially for children with earlier pubertal timing.

Obesity and Hypogonadism-A Narrative Review Highlighting the Need for High-Quality Data in Adolescents

The prevalence of obesity continues to rise in adult and pediatric populations throughout the world. Obesity has a direct impact on all organ systems, including the reproductive system. This review summarizes current knowledge about the effects of obesity on the male reproductive system across age, highlighting the need for more data in children and adolescents. Male hypogonadism is commonly seen in patients with obesity and affects the onset, duration, and progression of puberty. Different pathophysiologic mechanisms include increased peripheral conversion of testosterone to estrone and increased inflammation due to increased fat, both of which lead to suppression of the hypothalamic-pituitary-gonadotropin (HPG) axis and delayed development of secondary sexual characteristics in adolescent males. Evaluation of the HPG axis in obesity includes a thorough history to exclude other causes of hypogonadism and syndromic associations. Evaluation should also include investigating the complications of low testosterone, including increased visceral fat, decreased bone density, cardiovascular disease risk, and impaired mood and cognition, among others. The mainstay of treatment is weight reduction, but medications such as testosterone and clomiphene citrate used in adults, remain scarcely used in adolescents. Male hypogonadism associated with obesity is common and providers who care for adolescents and young adults with obesity should be aware of its impact and management.

Is there a causal relationship between obesity and puberty?

The onset of puberty in adolescents and whether it is related to obesity is an ongoing topic for debate. Epidemiological cross-sectional and longitudinal studies show a shift towards earlier onset of puberty in girls who are obese; however, the situation is less clear in boys. Boys who are overweight seem to mature earlier, and boys who are obese mature later, than boys at a healthy weight. The underlying mechanisms are not yet fully understood, and whether earlier onset of puberty in obese girls is based on the activation of the hypothalamic-pituitary-gonadal axis is unclear. The most promising link between obesity and puberty is the adipokine leptin and its interaction with the kisspeptin system, which is an important regulator of puberty. However, peripheral action of adipose tissue (eg, via other adipokines, aromatase activity) could also be involved in changes to the onset of puberty. In addition, nutritional factors, epigenetics, or endocrine disrupting chemicals are potential mediators linking the onset of puberty to obesity. This Review summarises our knowledge concerning the relationship between obesity and onset and tempo of puberty, and the consequences of early puberty on obesity.

Association of prepubertal obesity with pubertal development in Chinese girls and boys: A longitudinal study

OBJECTIVES

The purpose of this study was to examine the association of prepubertal body mass index (BMI) and weight status with pubertal development in boys and girls in Chongqing, China.

METHODS

In a longitudinal study, 1237 students (695 boys and 542 girls) were recruited from Chongqing, China, and examined at baseline, then followed every 6 months for three and a half years. Height, weight, testicular volume, and breast development were measured at every examination. Age of first spermatorrhea and menarche were obtained from self-report. Subjects were divided into normal weight, overweight, and obese groups according to baseline BMI. Multivariable Cox regression analysis was used to examine the association of BMI and weight status with pubertal development.

RESULTS

In girls, higher prepubertal BMI increased the chance of earlier menarche (hazards ratio (HR): 1.205, 95% confidence interval (95% CI): 1.151-2.261) and breast development (HR: 1.092, 95% CI: 1.045-1.142). Girls in the overweight (HR: 2.605, 95% CI: 1.716-3.956) and obese (HR: 2.565, 95% CI: 1.603-4.103) groups had an increased risk of early menarche compared with those in the normal weight group, while only overweight was associated with an increased risk for earlier breast development (HR: 1.469, 95% CI: 1.024-2.108). In boys, higher prepubertal BMI was significantly associated with the timing of first spermatorrhea (HR: 1.054, 95% CI: 1.004-1.106) and testicular development (HR: 1.098, 95% CI: 1.063-1.135). Overweight (HR: 1.672, 95% CI: 1.204-2.322) and obesity (HR: 1.598, 95% CI: 1.135-2.249) increased the hazard of earlier testicular development compared with the normal weight group, while no significant differences were detected among the three weight groups in terms of time to first spermatorrhea.

CONCLUSIONS

Higher prepubertal BMI was associated with earlier puberty in both Chinese boys and girls.

Association between Body Mass Index and Serum Dehydroepiandrosterone Sulfate Level in 8-Year-Old Girls

Background

Adiposity may play a role as a potential trigger for adrenarche. The purpose of this study was to evaluate the association between body mass index (BMI) and serum dehydroepiandrosterone sulfate (DHEAS) level.

Methods

The medical records of 8-year-old girls who presented to our clinic between 2014 and 2016 with concerns regarding pubertal changes were retrospectively reviewed. The 192 girls were divided into two groups depending on activation of the hypothalamic-pituitary-gonadal (HPG) axis. Group I included 77 subjects with a breast Tanner stage 1 with unknown HPG axis or thelarche without activated HPG axis. Group II included 115 subjects with activated HPG axis. Serum DHEAS level ≥1.1 μmol/L was regarded as biochemical adrenarche.

Results

Based on correlation analyses, BMI standard deviation score (SDS) was positively correlated with height SDS, bone age divided by chronological age (BA/CA), and DHEAS level in all subjects (r=0.269, r=0.270, r=0.298; all P<0.001, respectively). BMI SDS was negatively correlated with peak luteinizing hormone level in group II (r=−0.236, P=0.011). Based on multiple linear regression analyses, BMI SDS was associated with serum DHEAS level in all subjects (β=0.280, P<0.001), group I (β=0.415, P=0.001), and group II (β=0.206, P=0.030). DHEAS level was also associated with BA/CA in all subjects (β=0.402, P<0.001), group I (β=0.494, P<0.001), and group II (β=0.347, P<0.001).

Conclusion

BMI SDS was associated with DHEAS level, which was associated with BA/CA. Childhood obesity may influence the development of adrenarche, which may contribute to advanced skeletal maturation.

The association between skeletal maturation and adrenal androgen levels in obese children and adolescents

PURPOSE

This study aimed to investigate the association between skeletal maturation and adrenal androgen levels in obese children and adolescents.

METHODS

Fifty-three children and adolescents (aged 7-15 years) diagnosed as obese or overweight were investigated. Anthropometric measurements, bone age (BA) determination, serum biochemical analyses, and hormonal measurements were performed. The difference between BA and chronological age (BA-CA, dBACA) was calculated and used to represent the degree of advanced skeletal maturation.

RESULTS

Thirty-one subjects were classified into the obese group and 22 subjects into the overweight group. Insulin resistance as calculated by the homeostasis model assessment of insulin resistance (HOMA-IR) was significantly higher in the obese group than in the overweight group (4.03±2.20 vs. 2.86±1.11, P=0.026). The skeletal maturation of the obese group was advanced, but the dBACA did not differ between the obese and overweight groups statistically (1.43±1.35 vs. 0.91±1.15, P=0.141). Serum dehydroepiandrosterone sulfate (DHEA-S) levels were significantly higher in subjects with dBACA>1 compared to those with dBACA≤1 (104.3±62.2 vs. 59.6±61.0, P=0.014). Correlation analyses demonstrated that dBACA was positively correlated with body mass index standard deviation scores (r=0.35, P=0.010), fasting insulin (r=0.36, P=0.009), HOMA-IR (r=0.30, P=0.031), and insulin-like growth factor-binding protein-3 (r=0.331, P=0.028). In multivariate linear regression analysis, HOMA-IR (P=0.026) and serum DHEA-S (P=0.032) were positively correlated with the degree of advanced skeletal maturation.

CONCLUSION

Advanced skeletal maturation is associated with increased insulin resistance and elevated DHEA-S levels in obese children and adolescents.

Effect of Weight Loss on Puberty Onset in Overweight Children

OBJECTIVE

To assess the impact of weight changes on the onset of puberty in overweight children.

STUDY DESIGN

We evaluated the timing of puberty onset in 160 prepubertal overweight children (aged 11.2 ± 1.0 years) depending on the changes of their weight status in a 1-year lifestyle intervention. We determined body mass index (BMI), pubertal stage, luteinizing hormone (LH), follicle-stimulating hormone, insulin-like growth factor (IGF)-1, insulin-like growth factor binding protein-3, insulin resistance index homeostatic model assessment, and serum gonadotropins at baseline and 1 year later.

RESULTS

Puberty onset during the 1-year follow-up was significantly (P = .014) more frequent in girls without BMI-SDS reduction (75.0%) compared with girls with BMI-SDS reduction (45.7%). The start of puberty was significantly (P = .024) more frequent in boys with BMI-SDS reduction (76.9%) compared with boys without BMI-SDS reduction (53.6%). In logistic regression analyses adjusted for baseline age and BMI-SDS, BMI-SDS reduction was associated with a decreased likelihood for puberty onset in girls (OR 0.24; 95% CI 0.07-0.85) and an increased likelihood in boys (OR 3.77; 95% CI 1.34-10.52). Central onset of puberty was confirmed by an increase of LH concentration and LH/follicle-stimulating hormone ratio in both boys and girls. Homeostatic model assessment, IGF-1, and IGF-1/insulin-like growth factor binding protein-3 ratio as marker for free IGF-1 at baseline or their changes were not associated with the onset of puberty.

CONCLUSIONS

BMI-SDS reduction in overweight children was associated with earlier gonadotropin-dependent onset of puberty in boys and later onset of puberty in girls, suggesting earlier puberty in obese girls and later puberty in obese boys. We found no evidence that insulin resistance or IGF-1 have an impact on the start of puberty in obese children.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00435734.

Hyperphagia in male melanocortin 4 receptor deficient mice promotes growth independently of growth hormone

KEY POINTS

Loss of function of the melanocortin 4 receptor (MC4R) results in hyperphagia, obesity and increased growth. Despite knowing that MC4Rs control food intake, we are yet to understand why defects in the function of the MC4R receptor contribute to rapid linear growth. We show that hyperphagia following germline loss of MC4R in male mice promotes growth while suppressing the growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis. We propose that hyperinsulinaemia promotes growth while suppressing the GH-IGF-1 axis. It is argued that physiological responses essential to maintain energy flux override conventional mechanisms of pubertal growth to promote the storage of excess energy while ensuring growth.

ABSTRACT

Defects in melanocortin-4-receptor (MC4R) signalling result in hyperphagia, obesity and increased growth. Clinical observations suggest that loss of MC4R function may enhance growth hormone (GH)-mediated growth, although this remains untested. Using male mice with germline loss of the MC4R, we assessed pulsatile GH release and insulin-like growth factor-1 (IGF-1) production and/or release relative to pubertal growth. We demonstrate early-onset suppression of GH release in rapidly growing MC4R deficient (MC4RKO) mice, confirming that increased linear growth in MC4RKO mice does not occur in response to enhanced activation of the GH-IGF-1 axis. The progressive suppression of GH release in MC4RKO mice occurred alongside increased adiposity and the progressive worsening of hyperphagia-associated hyperinsulinaemia. We next prevented hyperphagia in MC4RKO mice through restricting calorie intake in these mice to match that of wild-type (WT) littermates. Pair feeding of MC4RKO mice did not prevent increased adiposity, but attenuated hyperinsulinaemia, recovered GH release, and normalized linear growth rate to that seen in pair-fed WT littermate controls. We conclude that the suppression of GH release in MC4RKO mice occurs independently of increased adipose mass, and is a consequence of hyperphagia-associated hyperinsulinaemia. It is proposed that physiological responses essential to maintain energy flux (hyperinsulinaemia and the suppression of GH release) override conventional mechanisms of pubertal growth to promote the storage of excess energy while ensuring growth. Implications of these findings are likely to extend beyond individuals with defects in MC4R signalling, encompassing physiological changes central to mechanisms of growth and energy homeostasis universal to hyperphagia-associated childhood-onset obesity.

New reference centiles for boys' height, weight and body mass index used voice break as the marker of biological age

AIM

We aimed to develop the first references for body height, body weight and body mass index (BMI) for boys based on the individual developmental tempo with respect to their voice break status.

METHODS

We re-analysed data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS study) on body height, body weight and body mass index based on the voice break, or mutation, in 3956 boys aged 10-17 years. We used the LMS method to construct smoothed references centiles for the studied variables in premutational, mutational and postmutational boys.

RESULTS

Body height, body weight and BMI differed significantly (p < 0.001) between the different stages of voice break. On average, boys were 5.9 cm taller, 5.8 kg heavier and had a 0.7 kg/m² higher BMI with every higher stage of voice break. Currently used growth references for chronological age in comparison with maturity-related references led to an average of 5.4% of boys being falsely classified as overweight.

CONCLUSION

These newly developed growth references allowed convenient classifications of underweight and overweight or obese boys with respect to their voice break status. They should be added to currently used references centiles for the body mass index to avoid misclassifying boys' weight.

Growth in Total Height and Its Components and Cardiometabolic Health in Childhood

BACKGROUND

Short stature or short legs is associated with cardiometabolic disease. Few studies have addressed this issue in children, incorporated repeated measures, or studied modern cohorts.

METHODS

We examined if change in total height, leg length and trunk length between two time points from early (median: 3.2 years) to mid-childhood (median: 7.7 years), with and without adjustment for concurrent change in adiposity (subscapular plus triceps skinfold thickness), was associated with mid-childhood cardiometabolic risk in 315 boys and 295 girls from Project Viva. The main outcome was a cardiometabolic risk score based on sex-specific internal z-scores for systolic blood pressure, waist circumference, homeostatic model assessment of insulin resistance, triglycerides and high-density lipoprotein-cholesterol.

RESULTS

Mean (SD) total height was 97.9 (4.5) cm in boys and 97.1 (4.7) cm in girls in early childhood and 129.1 (7.2) cm in boys and 128.3 (7.9) cm in girls in mid-childhood. Trunk length constituted about half of total height. In linear regression models adjusted for parental anthropometry and socio-demographics, faster growth in total height, leg length and particularly trunk length, were associated with higher cardiometabolic risk in mid-childhood. Per 1 cm annual increase in trunk length, the cardiometabolic risk score was 0.23 z-score (95% confidence interval [CI] 0.08, 0.39) higher among boys and 0.47 z-score (95% CI 0.33, 0.60) higher among girls. Estimates were attenuated after adjusting for adiposity (boys: 0.03 z-score, 95% CI -0.11, 0.18; girls: 0.32 z-score, 95% CI 0.19, 0.45).

CONCLUSION

Rapid linear growth, particularly in trunk length, was associated with higher cardiometabolic risk in childhood, which was explained by relationships of linear growth with adiposity in boys, but only partly in girls.

Low insulin-like growth factor 1 is associated with low high-density lipoprotein cholesterol and metabolic syndrome in Chinese nondiabetic obese children and adolescents: a cross-sectional study

Background

Low serum high-density lipoprotein cholesterol (HDL-C) is an independent risk factor for developing cardiovascular disease. Insulin-like growth factor 1(IGF-1) levels have been proven to be positively associated with HDL-C, but few studies were based on the dataset of children or adolescents. The aim of this study is to investigate the relationship among IGF-1, HDL-C and the metabolic syndrome in Chinese nondiabetic obese children and adolescents.

Methods

As a cross-sectional study, this study includes 120 obese Chinese children and adolescents and 120 healthy ones. The obese subjects were divided into two groups based on using 1.03 mmol/L as a threshold value for HDL-C. Clinical examination and laboratory examinations were assessed for all participants.

Results

Obese subjects had significantly lower IGF-1SDS and higher Height SDS than those in the control group. Among 120 obese children and adolescents, 22 (18.3 %) subjects had an HDL-C level <1.03 mmol/L. IGF-1SDS was significantly lower (P = 0.001) in obese subjects with low HDL-C. According to the results of multivariate logistic regression analysis, IGF-1 SDS is significantly associated with low HDL-C(OR 0.518, 95 % CI 0.292–0.916; P = 0.024), after being adjusted for age, gender, pubertal status, BMI SDS, SBP, DBP, HOMR-IR, total cholesterol, low density lipoprotein-cholesterol, triglycerides, ALT and uric acid. In addition, IGF-1 SDS is significantly correlated with the level of serum HDL-C in study population (r = 0.19, P = 0.003). Based on logistic regression analysis with adjustment for age, gender and pubertal status, the increased IGF-1 SDS was associated with a decreased probability of metabolic syndrome (OR 0.555, 95 % CI 0.385–0.801; P = 0.002) and hypertriglyceridemia (OR 0.582, 95 % CI 0.395–0.856; P = 0.006), but no significant correlation with hypertension.

Conclusion

Obese children had lower IGF-1SDS and taller stature compared with the control group. Low levels of IGF-1 SDS were associated with low levels of HDL-C in chinese nondiabetic obese children and adolescents, independent of insulin resistance, as well as other traditional cardiovascular disease risk markers.

Androgens and obesity in male adolescents

PURPOSE OF REVIEW

Data on sex steroid levels and pubertal development in obese adolescent boys are scarce and contrasting. The present review summarizes the most recent results obtained with improved methodology to measure low sex steroid levels in children.

RECENT FINDINGS

Obese pubertal boys have lower serum sex hormone-binding globulin and consequently lower total testosterone levels compared to normal-weight peers. However, during pubertal development, free testosterone levels in obese adolescents are not different from controls, indicating preserved androgen exposure as is additionally suggested by similar clinical genital staging (Tanner), serum gonadotropins levels, and serum prostate-specific antigen concentrations compared to nonobese adolescents. In pre and early puberty, total testosterone levels is not decreased, notwithstanding low sex hormone-binding globulin, and free testosterone is slightly increased in obese boys. This may result from increased adrenal activity as revealed by elevated serum androstenedione and dehydroepiandrosterone sulfate. In obese adolescent boys, increased aromatization of testosterone to estradiol tends to accelerate skeletal maturation.

SUMMARY

In obese adolescent boys, free testosterone is a better index than total testosterone levels of androgen status, which is not different from nonobese controls. Increased aromatization of testosterone to estradiol underlies the dissociation between normal clinical sexual maturation and advanced skeletal maturation in the obese adolescent.

The gonadal function in obese adolescents: review

This review deals with the relationship between obesity in male adolescents and gonadal function. The article is structured in two main paragraphs; the first one is about population studies that have assessed puberty timing and its mode of onset in relation with body weight to evaluate if and how the latter can influence the gonadal function in this phase of life. These studies analyze issues such as increased BMI and early onset of male puberty, gender differences, secular trend toward early onset of puberty in males, effects of a different body composition on male puberty and consequences of a different stage of childhood obesity on the onset of male puberty. The second paragraph examines the possible mechanisms through which, obesity may alter the timing of puberty in young males, including the role of SHBG, leptin, insulin resistance, ghrelin, GH-IGF-1 axis, AR polymorphisms, primary testicular dysfunction, retinol binding protein 4 (RBP-4) and liver function abnormalities. However, despite the numerous studies in the literature, the etiology of gonadal disfunction in obese adolescents on puberty remains uncertain.

Sex steroids in relation to sexual and skeletal maturation in obese male adolescents

BACKGROUND

Childhood obesity is associated with an accelerated skeletal maturation. However, data concerning pubertal development and sex steroid levels in obese adolescents are scarce and contrasting.

OBJECTIVES

To study sex steroids in relation to sexual and skeletal maturation and to serum prostate specific antigen (PSA), as a marker of androgen activity, in obese boys from early to late adolescence.

METHODS

Ninety obese boys (aged 10-19 y) at the start of a residential obesity treatment program and 90 age-matched controls were studied cross-sectionally. Pubertal status was assessed according to the Tanner method. Skeletal age was determined by an x-ray of the left hand. Morning concentrations of total testosterone (TT) and estradiol (E2) were measured by liquid chromatography-tandem mass spectrometry, free T (FT) was measured by equilibrium dialysis, and LH, FSH, SHBG, and PSA were measured by immunoassays.

RESULTS

Genital staging was comparable between the obese and nonobese groups, whereas skeletal bone advancement (mean, 1 y) was present in early and midadolescence in the obese males. Although both median SHBG and TT concentrations were significantly (P < .001) lower in obese subjects during mid and late puberty, median FT, LH, FSH, and PSA levels were comparable to those of controls. In contrast, serum E2 concentrations were significantly (P < .001) higher in the obese group at all pubertal stages.

CONCLUSION

Obese boys have lower circulating SHBG and TT, but similar FT concentrations during mid and late puberty in parallel with a normal pubertal progression and serum PSA levels. Our data indicate that in obese boys, serum FT concentration is a better marker of androgen activity than TT. On the other hand, skeletal maturation and E2 were increased from the beginning of puberty, suggesting a significant contribution of hyperestrogenemia in the advancement of skeletal maturation in obese boys.

Sexual dimorphisms in the associations of BMI and body fat with indices of pubertal development in girls and boys

CONTEXT

The effect of obesity and concomitant insulin resistance on pubertal development is incompletely elucidated.

OBJECTIVE

To determine how measures of adiposity and insulin resistance are associated with pubertal maturation in boys and girls.

SETTING AND DESIGN

Breast and pubic hair Tanner stage and testicular volume by orchidometry were determined by physical examination in 1066 children. Ovarian volume was estimated by trans-abdominal ultrasound. Fat mass, skeletal age, and fasting serum for insulin and glucose, total T, estradiol, estrone, dehydroepiandrosterone-sulfate, and androstenedione were measured at the National Institutes of Health Clinical Research Center. Convenience sample; 52% obese, 59% female.

RESULTS

Logistic regression identified a significant interaction between sex and obesity for prediction of pubertal development (P ≤ .01). There was a negative association between boys' testicular volume and body mass index (BMI)/fat mass but a positive association between girls' breast stage and BMI/fat mass. Ovarian volume in girls was positively associated with insulin resistance but not with BMI/fat mass. There was a positive association between obesity and measures of estrogen exposure (breast development and skeletal age) in both sexes. Positive correlations were seen for girls between BMI and pubic hair development and between insulin resistance and T production, whereas adiposity was negatively associated with pubic hair in boys.

CONCLUSIONS

Significant sexual dimorphisms in the manifestations of pubertal development are seen in obese girls and boys. Two known effects of obesity, increased peripheral conversion of low-potency androgens to estrogens by adipose tissue-aromatase and increased insulin resistance, may be in large part responsible for these differences.

[Does childhood obesity affect sexual development?]

The process of pubertal development is only partly understood and is influenced by many different factors. During the twentieth century there was a general trend toward earlier pubertal development. Fat mass is thought to be a major inducer of puberty. Owing to the rising epidemic of childhood obesity, the relationship between body composition in children and the rate and timing of puberty needs to be investigated. Some studies suggest that central obesity is associated with an earlier onset of pubertal development. Rapid weight gain in early life is linked to advanced puberty in both sexes. A clear correlation exists between increasing body mass index (BMI) and earlier pubertal development in girls. In boys the data are controversial: The majority of studies propose that there is an earlier puberty and voice break in obese boys, but some studies show the opposite. There are several factors and mechanisms that seem to link obesity and puberty, for example, leptin, adipocytokines, and gut peptides. Important players include genetic variation and environmental factors (e.g., endocrine-disrupting chemicals). This article presents the latest studies and evidence on this topic, underlining the inconsistencies in the data and, therefore, the need for further research in this area.

Energy dense, protein restricted diet increases adiposity and perturbs metabolism in young, genetically lean pigs

Animal models of obesity and metabolic dysregulation during growth (or childhood) are lacking. Our objective was to increase adiposity and induce metabolic syndrome in young, genetically lean pigs. Pre-pubertal female pigs, age 35 d, were fed a high-energy diet (HED; n = 12), containing 15% tallow, 35% refined sugars and 9.1–12.9% crude protein, or a control corn-based diet (n = 11) with 12.2–19.2% crude protein for 16 wk. Initially, HED pigs self-regulated energy intake similar to controls, but by wk 5, consumed more (P<0.001) energy per kg body weight. At wk 15, pigs were subjected to an oral glucose tolerance test (OGTT); blood glucose increased (P<0.05) in control pigs and returned to baseline levels within 60 min. HED pigs were hyperglycemic at time 0, and blood glucose did not return to baseline (P = 0.01), even 4 h post-challenge. During OGTT, glucose area under the curve (AUC) was higher and insulin AUC was lower in HED pigs compared to controls (P = 0.001). Chronic HED intake increased (P<0.05) subcutaneous, intramuscular, and perirenal fat deposition, and induced hyperglycemia, hypoinsulinemia, and low-density lipoprotein hypercholesterolemia. A subset of HED pigs (n = 7) was transitioned back to a control diet for an additional six weeks. These pigs were subjected to an additional OGTT at 22 wk. Glucose AUC and insulin AUC did not improve, supporting that dietary intervention was not sufficient to recover glucose tolerance or insulin production. These data suggest a HED may be used to increase adiposity and disrupt glucose homeostasis in young, growing pigs.

Puberty in girls of the 21st century

Several studies have noted contemporary girls are undergoing pubertal maturation at younger ages. During this same time period many Western nations have experienced an obesity epidemic, prompting investigators and public health officials to consider the association of these 2 events, and if other exposures might impact this relationship. There are several potential mechanisms that could impact the relationship of pubertal timing in girls with greater body mass, including direct effects of obesity on pubertal timing as well underlying exposures that impact body mass as well as timing of pubertal maturation. These underlying conditions include chemical compounds that could impact synthesis or action of sex hormones, called endocrine disrupting chemicals (EDs). We examine the decline in the age of breast development and potential genetic and environmental influences, the obesity epidemic in the US and other nations, and potential mechanisms to explain the relationship between greater body mass index with earlier puberty in girls.

The physiology and timing of male puberty

PURPOSE OF REVIEW

To describe available markers of male puberty, discuss associations between adiposity and pubertal timing and to review recent evidence of a possible secular trend in male pubertal timing.

RECENT FINDINGS

An expert panel reviewing existing American pubertal data from boys in 2005 could not confirm a secular trend in male pubertal timing. National Health and Nutrition Examination Survey III findings have been confirmed by the National Institute of Child Health and Human Development study reporting a mean age of 10.4 years for Caucasian boys entering Tanner stage G2. Furthermore, the Copenhagen Puberty Study reported a 3 months decline in pubertal onset during a 15-year period (from 11.92 years in 1991 to 11.66 years in 2008).A negative association between obesity and early puberty was found in the National Institute of Child Health and Human Development study, in contrast to the positive association found in a Danish study. Other studies have not been able to document an association between prepubertal BMI and age at pubertal onset.

SUMMARY

Evaluation of Tanner stage and especially assessment of testicular volume should both be used in epidemiological studies. We speculate that the association between fat mass and pubertal timing may be nonlinear and recent studies may indicate a small decline in age at pubertal onset in boys.

Socio-demographic and lifestyle determinants of 'Western-like' and 'Health conscious' dietary patterns in toddlers

Determinants of a child's diet shortly after weaning and lactation have been relatively understudied. The aim of the present study was hence to identify common dietary patterns in toddlers and to explore parental and child indicators of these dietary patterns. The study was a population-based, prospective birth-cohort study in Rotterdam, the Netherlands. Food consumption data of 2420 children aged 14 months were used. A 'Health conscious' dietary pattern characterised by pasta, fruits, vegetables, oils, legumes and fish, and a 'Western-like' dietary pattern characterised by snacks, animal fats, confectionery and sugar-containing beverages were extracted using principal component analysis. Low paternal education, low household income, parental smoking, multiparity, maternal BMI, maternal carbohydrate intake and television-watching of child were determinants of a 'Western-like' diet, whereas parental age, dietary fibre intake during pregnancy, introduction of solids after 6 months and female sex were inversely associated with a 'Western-like' diet of the child. Maternal co-morbidity, alcohol consumption during pregnancy and female sex were inversely associated with a 'Health conscious' dietary pattern of the child, while single parenthood, folic acid use and dietary fibre intake during pregnancy were positively associated. All aforementioned associations were statistically significant. In conclusion, both 'Western-like' and 'Health conscious' diets can already be identified in toddlers. Particularly, adherence to a 'Western-like' diet is associated with unfavourable lifestyle factors of the parents and child, and low socio-economic background. These findings can form a basis for future epidemiological studies regarding dietary patterns and health outcomes in young children.

Effects of obesity on human sexual development

Puberty is a period of physical and psychological maturation, with long-term effects on health. During the 20(th) century, a secular trend towards earlier puberty occurred in association with improvements in nutrition. The worldwide pandemic of childhood obesity has renewed interest in the relationship between body composition in childhood and the timing and tempo of puberty. Limited evidence suggests that earlier puberty is associated with a tendency towards central fat deposition; therefore, pubertal status needs to be carefully considered in the categorization of childhood and adolescent overweight and obesity. In the other direction, rapid early weight gain is associated with advanced puberty in both sexes, and a clear association exists between increasing BMI and earlier pubertal development in girls. Evidence in boys is less clear, with the majority of studies showing obesity to be associated with earlier puberty and voice break, although a subgroup of boys with obesity exhibits late puberty, perhaps as a variation of constitutional delay in growth and puberty. The possible mechanisms linking adiposity with pubertal timing are numerous, but leptin, adipocytokines and gut peptides are central players. Other possible mediators include genetic variation and environmental factors such as endocrine disrupting chemicals. This Review presents current evidence on this topic, highlighting inconsistencies and opportunities for future research.