Age at Puberty and the Emerging Obesity Epidemic

Background

Recent studies have shown that puberty starts at younger ages than previously. It has been hypothesized that the increasing prevalence of childhood obesity is contributing to this trend. The purpose of this study was to analyze the association between prepubertal body mass index (BMI) and pubertal timing, as assessed by age at onset of pubertal growth spurt (OGS) and at peak height velocity (PHV), and the secular trend of pubertal timing given the prepubertal BMI.

Methodology/Principal Findings

Annual measurements of height and weight were available in all children born from 1930 to 1969 who attended primary school in the Copenhagen municipality; 156,835 children fulfilled the criteria for determining age at OGS and PHV. The effect of prepubertal BMI at age seven on these markers of pubertal development within and between birth cohorts was analyzed. BMI at seven years was significantly inversely associated with age at OGS and PHV. Dividing the children into five levels of prepubertal BMI, we found a similar secular trend toward earlier maturation in all BMI groups.

Conclusion/Significance

The heavier both boys and girls were at age seven, the earlier they entered puberty. Irrespective of level of BMI at age seven, there was a downward trend in the age at attaining puberty in both boys and girls, which suggests that the obesity epidemic is not solely responsible for the trend.     

Trends in Parent-Child Correlations of Childhood Body Mass Index during the Development of the Obesity Epidemic

Background

The intergenerational resemblance in body mass index may have increased during the development of the obesity epidemic due to changes in environment and/or expression of genetic predisposition.

Objectives

This study investigates trends in intergenerational correlations of childhood body mass index (BMI; kg/m²) during the emergence of the obesity epidemic.

Methods

The study population was derived from the Copenhagen School Health Records Register, which includes height and weight measurements since birth year 1930. Mothers and fathers with BMIs available at ages 7 (n = 25,923 and n = 20,972) or 13 years (n = 26,750 and n = 21,397), respectively, were linked through the civil registration system introduced in 1968 to their children with BMIs available at age 7 years. Age- and sex-specific BMI z-scores were calculated. Correlations were estimated across eight intervals of child birth years (1952–1989) separately by sex. Trends in these correlations were examined. Whereas the mother-child correlations reflected the biological relationship, a likely decline in the assignment of non-biological fathers through the registration system across time must be considered when interpreting the father-child correlations.

Results

The BMI correlations between mothers and sons ranged from 0.29–0.36 and they decreased marginally, albeit significantly across time at ages 7–7 years (−0.002/year, p = 0.006), whereas those at 13–7 years remained stable (<0.0004/year, p = 0.96). Mother-daughter correlations ranged from 0.30–0.34, and they were stable at ages 7–7 years (0.0001/year, p = 0.84) and at 13–7 years (0.0004/year, p = 0.56). In contrast, father-son correlations increased significantly during this period, both at ages 7–7 (0.002/year, p = 0.007) and at ages 13–7 years (0.003/year, p<0.001), whereas the increase in father-daughter correlations were insignificant both at ages 7–7 (0.001/year, p = 0.37) and at ages 13–7 years (0.001/year, p = 0.18).

Conclusion

During the obesity epidemics development, the intergenerational resemblance with mothers remained stable, whereas the father-child BMI resemblance increased, possibly reflecting changes in family relationships, and unlikely to have influenced the epidemic.     

Stability of the Association between Birth Weight and Childhood Overweight during the Development of the Obesity Epidemic

Objective: To assess whether changes in the birth weight distribution or changes in the association of birth weight with the later risk of childhood overweight have contributed to the development of the obesity epidemic. Research Methods and Procedures: A Danish population‐based cohort study of 124,615 girls and 128,346 boys (ages 6 to 13 years), born between 1936 and 1983, were studied. Birth weight and annual measurements of height and weight were obtained from school health records. Overweight was defined by BMI in relation to internationally accepted criteria. The relative risk of being overweight by birth weight was calculated separately for each age, sex, and time period. Results: The birth weight distribution remained relatively stable over time. Compared with children with a birth weight of 3.0 to 3.5 kg, the risk of overweight increased consistently with each increase in birth weight category among girls and boys and at all ages between 6 and 13 years. Furthermore, the association between birth weight and increased risk of overweight in childhood remained stable across a 48‐year period. Discussion: The increase in the prevalence of overweight could not be explained by time trends in the distribution of birth weight or by changes in the association between birth weight and the later risk of overweight over time. This implies that, unless the prenatal environment influences the later risk of overweight without increasing birth weight, the environmental influences contributing to the obesity epidemic in children of school age operate in the early postnatal period.     

Muscular Strength Is Inversely Related to Prevalence and Incidence of Obesity in Adult Men

The purpose of the study was to determine the relation between quintiles of muscular strength after adjustment for age and body weight, and excessive body fat (EBF) and excessive abdominal fat (EAF) when controlling for cardiorespiratory fitness (CRF) and other potential confounders. A two‐phased cross‐sectional and longitudinal study was conducted assessing the prevalence and incidence of EBF and EAF across quintiles of muscular strength. The sample included 3,258 men (mean age = 42.2 ± 8.9; weight (kg) = 81.2 ± 11.0; BMI = 25.3 ± 2.9; %fat = 19.4 ± 5.8; waist girth (cm) = 91.2 ± 9.0) who completed at least two clinical examinations as part of the Aerobics Center Longitudinal Study (ACLS). Muscular strength was assessed with tests of upper and lower body muscular strength using rack‐mounted weights with participants placed into strength quintiles. CRF was measured by a modified Balke treadmill test, %fat via underwater weighing or seven‐site skinfold measurements, and waist girth measured at the level of the umbilicus. EBF was defined as ≥25% and EAF was defined as >102 cm. There was a strong inverse gradient across quintiles of muscular strength for prevalence and incidence of EBF and EAF (P trend <0.01, each). With the lowest quintile serving as the referent, reductions in risk of EBF and EAF exceeded 70% for the highest strength quintile. Evidence suggests muscular strength may provide protection from EBF and EAF and their related comorbidities.     

Childhood and Young Adult Overweight/Obesity and Incidence of Depression in the SUN Project

This study included 11,825 participants of a Spanish dynamic prospective cohort based on former students from University of Navarra, registered professionals from some Spanish provinces, and university graduates from other associations, followed‐up for 6.1 years. We aimed to assess the association between childhood or young adult overweight/obesity and the risk of depression. Participants were asked to select which of nine figures most closely represented their body shape at ages 5 and 20 years. Childhood and young adult overweight/obesity was defined as those cases in which participants reported body shape corresponding to the figures 6–9 (more obese categories) at age 5 or 20, respectively. A subject was classified as incident case of depression if he/she was initially free of depression and reported physician‐made diagnosis of depression and/or the use of antidepressant medication in at least one of biannual follow‐up questionnaires. The association between childhood and young adult overweight/obesity and incidence of depression was estimated by multiple‐adjusted hazard ratio (HR) and its 95% confidence interval (95% CI). Overweight/obesity at age 5 years predicted an increased risk for adult depression (HR = 1.50, 95% CI = 1.06–2.12), and a stronger association was observed at age 20 years ((HR = 2.22, 95% CI = 1.22–4.08), (subjects younger than 30 years at recruitment were excluded from this last analysis)). Childhood or young adult overweight/obesity was associated with elevated risk of adult depression. These results, if causal and confirmed in other prospective studies, support treating childhood and young adult overweight/obesity as part of comprehensive adult depression prevention efforts.     

Complementary Hypotheses on Contributors to the Obesity Epidemic

Increased rates of obesity have occurred within virtually every race, age, sex, ethnicity, and economic group. Despite substantial punditry on the issue, the exact reasons are incompletely known. The two most common factors cited as contributing to the obesity epidemic, and those whose causal influence on increasing obesity levels in the population are often presumed unequivocally, are food marketing practices and institutionally driven reductions in physical activity. These have been called “the big two.” This Perspective builds on previous writings in this area to introduce additional factors that may contribute to the obesity epidemic. It is emphasized that there may be other factors working in combination with the big two, influencing body fatness through effects on energy intake, energy expenditure, and/or nutrient partitioning.     

Exploiting Social Networks to Mitigate the Obesity Epidemic

Despite significant efforts, obesity continues to be a major public health problem, and there are surprisingly few effective strategies for its prevention and treatment. We now realize that healthy diet and activity patterns are difficult to maintain in the current physical environment. Recently, it was suggested that the social environment also contributes to obesity. Therefore, using network‐based interaction models, we simulate how obesity spreads along social networks and predict the effectiveness of large‐scale weight management interventions. For a wide variety of conditions and networks, we show that individuals with similar BMIs will cluster together into groups, and if left unchecked, current social forces will drive these groups toward increasing obesity. Our simulations show that many traditional weight management interventions fail because they target overweight and obese individuals without consideration of their surrounding cluster and wider social network. The popular strategy for dieting with friends is shown to be an ineffective long‐term weight loss strategy, whereas dieting with friends of friends can be somewhat more effective by forcing a shift in cluster boundaries. Fortunately, our simulations also show that interventions targeting well‐connected and/or normal weight individuals at the edges of a cluster may quickly halt the spread of obesity. Furthermore, by changing social forces and altering the behavior of a small but random assortment of both obese and normal weight individuals, highly effective network‐driven strategies can reverse current trends and return large segments of the population to a healthier weight.     

Increasing Rates of Obesity among HIV-Infected Persons during the HIV Epidemic

Background

The prevalence and factors associated with overweight/obesity among human immunodeficiency virus (HIV)-infected persons are unknown.

Methods

We evaluated prospective data from a U.S. Military HIV Natural History Study (1985–2004) consisting of early diagnosed patients. Statistics included multivariate linear regression and longitudinal linear mixed effects models.

Results

Of 1682 patients, 2% were underweight, 37% were overweight, and 9% were obese at HIV diagnosis. Multivariate predictors of a higher body mass index (BMI) at diagnosis included more recent year of HIV diagnosis, older age, African American race, and earlier HIV stage (all p<0.05). The majority of patients (62%) gained weight during HIV infection. Multivariate factors associated with a greater increase in BMI during HIV infection included more recent year of diagnosis, lower BMI at diagnosis, higher CD4 count, lower HIV RNA level, lack of AIDS diagnosis, and longer HIV duration (all p<0.05). Nucleoside agents were associated with less weight gain; other drug classes had no significant impact on weight change in the HAART era.

Conclusions

HIV-infected patients are increasingly overweight/obese at diagnosis and during HIV infection. Weight gain appears to reflect improved health status and mirror trends in the general population. Weight management programs may be important components of HIV care.     

Obesity and labor market outcomes in Denmark

This paper analyzes the relationship between body mass index (BMI) and employment status and wages. The analysis uses a unique data set from a Danish panel survey from 1995 and 2000, combined with administrative registers, covering 8000 individuals. Results show a negative effect of BMI on employment for women and an inverted u-shaped effect for men. Results further indicate that in the private sector BMI has a negative effect on wages for women but an inverted u-shaped effect on wages for men, whereas results from the public sector show that BMI has no influence on wages for either men or women.     

Effects of Climate on Incidence of Campylobacter spp. in Humans and Prevalence in Broiler Flocks in Denmark

Campylobacter infections are increasing and pose a serious public health problem in Denmark. Infections in humans and broiler flocks show similar seasonality, suggesting that climate may play a role in infection. We examined the effects of temperature, precipitation, relative humidity, and hours of sunlight on Campylobacter incidence in humans and broiler flocks by using lag dependence functions, locally fitted linear models, and cross validation methods. For humans, the best model included average temperature and sunlight 4 weeks prior to infection; the maximum temperature lagged at 4 weeks was the best single predictor. For broilers, the average and maximum temperatures 3 weeks prior to slaughter gave the best estimate; the average temperature lagged at 3 weeks was the best single predictor. The combined effects of temperature and sunlight or the combined effects of temperature and relative humidity predicted the incidence in humans equally well. For broiler flock incidence these factors explained considerably less. Future research should focus on elements within the broiler environment that may be affected by climate, as well as the interaction of microclimatic factors on and around broiler farms. There is a need to quantify the contribution of broilers as a source of campylobacteriosis in humans and to further examine the effect of temperature on human incidence after this contribution is accounted for. Investigations should be conducted into food consumption and preparation practices and poultry sales that may vary by season.     

Japanese Lifestyle during Childhood Prevents the Future Development of Obesity among Japanese-Americans

Objective

To evaluate whether a Japanese lifestyle during childhood could protect against the future development of obesity-associated metabolic diseases by comparing native Japanese with Japanese-Americans in whom genetic factors are the same.

Methods

Study subjects were 516 native Japanese and 781 Japanese-Americans who underwent medical examinations between 2007 and 2010. Japanese-Americans were divided into 444 first-generation immigrants (JA-1), who were born in Japan, and 337 second- or later-generation descendants (JA-2), who were born in the United States. The JA-2 group was then divided into the kibei subgroup (N = 79), who had moved to Japan before the age of 18 years and later returned to the United States, and the non-kibei subgroup (N = 258), who had never lived in Japan.

Results

The JA-2 group had the highest percentages of obesity, metabolic syndrome, and type 2 diabetes compared with native Japanese and JA-1. Furthermore, among JA-2, the prevalence of obesity and metabolic syndrome in the kibei subgroup was significantly lower than that in the non-kibei subgroup. The prevalence of diabetes in the kibei subgroup also tended to be lower than in the non-kibei subgroup.

Conclusions

The prevalence of obesity and metabolic diseases differed with residence in Japan during childhood among Japanese-Americans. These findings indicate the possibility that Japanese lifestyle during childhood could reduce the future risks for obesity-associated metabolic diseases.     

Preventing and Treating Obesity in Girls and Young Women to Curb the Epidemic

Obesity and its serious comorbidities, type 2 diabetes, coronary heart disease, hypertension, and dyslipidemia, have reached epidemic proportions in adults and children. Female obesity is more prevalent and, thus, has greater epidemiological importance: Mothers transmit the disease epigenetically and genetically. Maternal obesity affects maternal health, pregnancy outcome, and fetal, neonatal, childhood, and ultimately adult morbidity and mortality. Obesity is easy to diagnose, as are most of its risk factors, yet very little progress has been made in preventing the disease. During a brief period of rapid early growth, there is imprinting of antecedents of adult obesity and obesity‐related disease. Because of the rapidity of this early growth and the relative brevity of the critical period, early recognition and prompt intervention are necessary and possibly sufficient to prevent the development of obesity. Identification of inappropriate rapid weight gain through frequent weighing should trigger immediate adjustment of energy intake, a simple intervention in bottle‐fed infants, the ones at greatest risk for becoming obese. This review presents a step‐care strategy with fail‐safe action levels starting with maternal education and diet, exercise, and behavior modification for mother and child and progressing to drug treatment and, in selected cases, laparoscopic surgery for young women of childbearing age in whom other measures have failed. This approach is predicated on the assumption that careful monitoring and responsive supplementation of potential deficiencies is easier to achieve, more cost‐effective, and safer than effectively treating manifest obesity and its comorbidities in adults.     

Resilience and Risk: Childhood and Uncertainty in the AIDS Epidemic

In a study of depression and risk amongHIV-affected young people (children whose parents areinfected with or have died from HIV/AIDS), subjectsdid not report high risk sexual or substance usebehavior. Findings are attributed to parentalparticipation in a community-based HIV service programthat provides parents with HIV prevention educationand long term social and emotional support. Multi-generational community based models ofprevention that include parents as critical elementsof instruction may also be effective in substanceabuse treatment programs and in programs for childrenwho experience difficulty in school.     

Adaptability and Persistence of the Emerging Pathogen Bordetella petrii

The first described, environmentally isolated, Bordetella petrii was shown to undergo massive genomic rearrangements in vitro. More recently, B. petrii was isolated from clinical samples associated with jaw, ear bone, cystic fibrosis and chronic pulmonary disease. However, the in vivo consequences of B. petrii genome plasticity and its pathogenicity remain obscure. B. petrii was identified from four sequential respiratory samples and a post-mortem spleen sample of a woman presenting with bronchiectasis and cavitary lung disease associated with nontuberculous mycobacterial infection. Strains were compared genetically, phenotypically and by antibody recognition from the patient and from inoculated mice. The successive B. petrii strains exhibited differences in growth, antibiotic susceptibility and recognition by the patient’s antibodies. Antibodies from mice inoculated with these strains recapitulated the specificity and strain dependent response that was seen with the patient’s serum. Finally, we characterize one strain that was poorly recognized by the patient’s antibodies, due to a defect in the lipopolysaccharide O-antigen, and identify a mutation associated with this phenotype. We propose that B. petrii is remarkably adaptable in vivo, providing a possible connection between immune response and bacterial evasion and supporting infection persistence.     

Estimates of the Prevalence of Obesity in Canadian Children

Childhood obesity is becoming a topic of great concern due to the rising prevalence of this condition in North America. Studies conducted in the United States have indicated that the prevalence of obesity has increased dramatically over the past few decades. The purpose of this study was to estimate the prevalence of obesity in Canadian children between the ages of 5 and 12 years by examining data from two national and two regional surveys. The 85th percentiles of each of four anthropometric indices derived from large normative populations were used as diagnostic criteria for obesity. As expected, the resulting prevalences varied according to the criteria used. A significant increase in childhood obesity between the 1981 to 1988 national surveys was observed when the three indices which used skinfolds were applied. Weight-for-height percentiles did not indicate an increase in obesity in these samples. Regional samples showed a less than expected prevalence of obesity among the middle-class children and a higher than expected rate among the inner city boys. It can be concluded that there is a need for a defined criteria for identifying obesity in children in order to avoid confusion resulting from the wide variation in estimates of prevalence resulting from different standards and measurements. Using adiposity-based criteria for obesity it was clearly evident that the prevalence of obesity has increased in Canadian children.