The prevalence and severity of obesity have increased in recent years, likely the result of complex interactions between genes, dietary intake, physical activity, and the environment. The expression of genes favoring the storage of excess calories as fat, which have been selected for over many millennia and are relatively static, has become maladaptive in a rapidly changing environment that minimizes opportunities for energy expenditure and maximizes opportunities for energy intake. The consequences of childhood and adolescent obesity include earlier puberty and menarche in girls, type 2 diabetes and increased incidence of the metabolic syndrome in youth and adults, and obesity in adulthood. These changes are associated with cardiovascular disease as well as with several cancers in adults, likely through insulin resistance and production of inflammatory cytokines. Although concerns have arisen regarding environmental exposures, there have been no formal expert recommendations. Currently, the most important factors underlying the obesity epidemic are the current opportunities for energy intake coupled with limited energy expenditure.Am J Clin Nutr 2010;91(suppl):1499S-1505S.

No abstract

Since the early 1980s, the focus on the importance of puberty to adolescent development has continued with variability in the methodology selected to measure puberty. To capture the relevant and important issues regarding the measurement of puberty in the last decade, this paper will address (1) the neuroendocrine aspects of puberty and its components, as well as the timing of puberty and its tempo; (2) why puberty is measured, including the relevance of puberty and its timing to health and development as well as the relevance of being off-time, that is, early or late with respect to a reference group; (3) the measurement of puberty and its methodology with respect to pubertal staging by physical examination, self-report measures, and their agreement with other methods and measures, hormones and their methods of measurement, and comparison of hormone concentrations to pubertal stage; and (4) recommendations for what is needed in the next decade regarding the measurement of puberty.

OBJECTIVES The objective of this study was to describe the assessment methods and maturation status for a multisite cohort of girls at baseline recruitment and at ages 7 and 8 years. METHODS The method for pubertal maturation staging was developed collaboratively across 3 sites. Girls at ages 6 to 8 years were recruited at 3 sites: East Harlem, New York; greater Cincinnati metropolitan area; and San Francisco Bay area, California. Baseline characteristics were obtained through interviews with caregivers and anthropometric measurements by trained examiners; breast stage 2 was defined as onset of pubertal maturation. The κ statistic was used to evaluate agreement between master trainers and examiners. Logistic regression models were used to identify factors that are associated with pubertal maturation and linear regression models to examine factors that are associated with height velocity. RESULTS The baseline cohort included 1239 girls. The proportion of girls who had attained breast stage 2 varied by age, race/ethnicity, BMI percentile, and site. At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage ≥2; at 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage ≥2. The prime determinant of height velocity was pubertal status. CONCLUSIONS In this multisite study, there was substantial agreement regarding pubertal staging between examiners across sites. The proportion of girls who had breast development at ages 7 and 8 years, particularly among white girls, is greater than that reported from studies of girls who were born 10 to 30 years earlier.