Adolescent physical activity and sedentary behavior: patterning and long-term maintenance

BACKGROUND: Little is known about physical activity (PA) and sedentary behavior patterning or its impact on long-term PA sustainability, particularly during the critical transition from adolescence to adulthood. METHODS: Nationally representative self-reported data were collected (National Longitudinal Study of Adolescent Health: Wave I, 1994-1995; Wave II, 1996; Wave III, 2001-2002). Cluster analyses identified homogeneous groups of adolescents with similar PA and sedentary behaviors. Logistic regression predicted odds of meeting national activity recommendations in adolescence and young adulthood. RESULTS: Seven clusters were characterized as follows: C1, high television (TV)/video, video gaming; C2, high skating, video gaming; C3, high sports participation with parents, high overall sports participation; C4, use of neighborhood recreation centers, high sports participation; C5, TV viewing limited by parents, moderate participation in school physical education (PE); C6, low parental TV control, reporting few activities overall; C7, active in school (team/individual sports, academic clubs, and PE). Odds of adolescents meeting PA recommendations were highest in C2 (odds ratio=13.1), C3 (5.8), C4 (4.2), and C7 (4.3) compared to C1. Independent of adolescent PA, absolute odds of meeting recommendations as young adults declined but were still relatively high in these clusters, indicating greater long-term PA sustainability. By young adulthood, however, overall PA declined dramatically in skaters/gamers (C2) and was notably low among those with TV viewing limited by parents (C5). CONCLUSIONS: While odds of meeting PA guidelines in adulthood declined in all clusters, the magnitude of this decline varied by cluster (declining most dramatically in skaters/gamers), providing insights into where to target effective intervention strategies that promote sustainable PA behaviors.     

Are child eating patterns being transformed globally?

OBJECTIVE: To examine the extent to which child dietary patterns and trends are changing globally. RESEARCH METHODS AND PROCEDURES: Diets of children 2 to 19 years of age were studied with nationally representative data from Russia and the United States, nationwide data from China, and regional data from metropolitan Cebu, Philippines. Twenty-four-hour dietary recalls were examined at several points in time to examine trends in calories consumed away from home, snacking behavior, and soft drink and modern fast food consumption. Urban-rural trends were compared. RESULTS: U.S. and Cebu youth consume more than one-third of their daily calories and a higher proportion of snack calories from foods prepared away from home. In contrast, away from home food consumption is minimal in Chinese and Russian children. U.S. and Cebu youth consume about one-fifth of their total daily energy from snacks, but snacks provide a much lower proportion of energy in Russia ( approximately 16%) and China (where snacks provide only approximately 1% of energy). Fast food plays a much more dominant role in the American diet ( approximately 20% of energy vs. 2% to 7% in the other countries), but as yet does not contribute substantially to children's diets in the other countries. Urban-rural differences were found to be important, but narrowing over time, for China and Cebu, whereas they are widening for Russia. DISCUSSION: This research suggests that globalization of the fast food and other modern food sectors is beginning to affect child eating patterns in several countries undergoing nutrition transition. However, the contribution of fast food and soft drinks to the diet of children remains relatively small in China, Russia, and Cebu, Philippines, relative to the United States.     

The health impacts of globalisation: a conceptual framework

This paper describes a conceptual framework for the health implications of globalisation. The framework is developed by first identifying the main determinants of population health and the main features of the globalisation process. The resulting conceptual model explicitly visualises that globalisation affects the institutional, economic, social-cultural and ecological determinants of population health, and that the globalisation process mainly operates at the contextual level, while influencing health through its more distal and proximal determinants. The developed framework provides valuable insights in how to organise the complexity involved in studying the health effects resulting from globalisation. It could, therefore, give a meaningful contribution to further empirical research by serving as a 'think-model' and provides a basis for the development of future scenarios on health.     

The dual burden household and the nutrition transition paradox

OBJECTIVE: The purpose of this study is to document the prevalence of households with underweight and overweight persons (henceforth referred to as dual burden households) and their association with income and urban residence. The explorations by urban residence and income will test whether dual burden households differ from 'underweight only' and 'overweight only' households, respectively. These comparisons are relevant to differentiating or adapting nutrition-related interventions wherever obesity and undernutrition cluster at the household level. POPULATION: Data analysis is based on national surveys conducted in Brazil, China, Indonesia, the Kyrgyz Republic, Russia, Vietnam and the United States. METHODS: All persons were first classified into categories for underweight and overweight, using body mass index (BMI) cutoffs, and then all households were categorized into four types: dual burden, overweight, underweight and normal. Income and urban residence were explored as key risk factors for being a dual burden household, with the effects modeled separately for each country. Multiple logistic regression was used to explore income and urban risk factors, controlling for household size, region of residence and either urban residence or income, as appropriate. RESULTS: In six of the countries studied, 22-66% of households with an underweight person also had an overweight person. Countries with the highest prevalence of dual burden households were those in the middle range of gross national product (GNP). The dual burden household is easily distinguished from the 'underweight only' households in Brazil, China, Indonesia, the United States and Vietnam. In these five countries dual burden households were more likely to be urban and more likely to be among the highest income tertile. There were no significant differences between dual burden and 'underweight only' households in Russia and the Kyrgyz Republic. In contrast, dual burden households were not easily distinguished from the 'overweight only' households in China, Indonesia, the Kyrgyz Republic, the United States and Vietnam. In Brazil and Russia dual burden households were more likely to be lower income and urban than 'overweight only' households. CONCLUSION: The prevalence of dual burden households presents a significant public health concern, particularly for those countries in the middle range of GNP. In some countries (China, Indonesia, the Kyrgyz Republic, the United States and Vietnam), dual burden households share sociodemographic profiles with overweight households, raising concerns for underweight individuals who may inadvertently become the focus of obesity prevention initiatives. For this reason, obesity prevention efforts should focus on messages that are beneficial to the good health of all, such as increasing fruit and vegetable intake, improving overall diet quality and increasing physical activity.     

Obesity and inequities in health in the developing world

OBJECTIVE: To update the social distribution of women's obesity in the developing world and, in particular, to identify the specific level of economic development at which, if any, women's obesity in the developing world starts to fuel inequities in health. DESIGN: Multilevel logistic regression analyses applied to anthropometric and socioeconomic data collected by nationally representative cross-sectional surveys conducted from 1992 to 2000 in 37 developing countries within a wide range of world regions and stages of economic development (gross national product (GNP) from 190 to 4440 US dollars per capita). SUBJECTS:: In total, 148 579 nonpregnant women aged 20-49 y. MEASUREMENTS: Body mass index to assess obesity status; quartiles of years of education to assess woman's socioeconomic status (SES), and GNP per capita to assess country's stage of economic development. RESULTS: Belonging to the lower SES group confers strong protection against obesity in low-income economies, but it is a systematic risk factor for the disease in upper-middle income developing economies. A multilevel logistic model-including an interaction term between the country's GNP and each woman's SES-indicates that obesity starts to fuel health inequities in the developing world when the GNP reaches a value of about 2500 US dollars per capita. CONCLUSIONS: For most upper-middle income economies and part of the lower-middle income economies, obesity among adult women is already a relevant booster of health inequities and, in the absence of concerted national public actions to prevent obesity, economic growth will greatly expand the list of developing countries where this situation occurs.     

Understanding the role of mediating risk factors and proxy effects in the association between socio-economic status and untreated hypertension

The association between socio-economic status (SES) and untreated hypertension varies according to a country's level of development and racial/ethnic group. We sought to confirm this variation in women from China and the United States (US) as well as to investigate the impact of SES on several mediating risk factors. We also investigate the extent to which SES explains racial/ethnic differences in untreated hypertension in the US. We used cross-sectional data from 1814 non-pregnant women in China (China Health and Nutrition Survey (CHNS), 1997) and 3266 non-pregnant women in the United States (National Health and Nutrition Examination Survey (NHANES III), 1988-1994) respectively. A variety of statistical modelling techniques was used to predict untreated hypertension as a function of several mediating factors and to simulate the impact of changes in SES. The age-adjusted prevalence of untreated hypertension was significantly higher (p<0.01) for low-income White and Black women compared to Mexican American or Chinese women. Untreated hypertension was not significantly associated with income or education in Mexican Americans or women in China. Obesity and light physical activity had the largest mediating effect on the association between SES and untreated hypertension for all racial/ethnic groups. However, this effect was not as strong as the proxy effect of income and education. SES did not completely explain racial/ethnic differences in hypertension in the US. While SES was more strongly associated with hypertension in Blacks than Whites, Blacks were still 1.97 (95% CI 1.47-2.64) times more likely to have untreated hypertension than Whites after adjusting for SES differences. The association between SES and untreated hypertension varied by country and racial/ethnic group. An important explanation for this variation was the differential effect of SES on mediating risk factors. SES disparities between Whites and Blacks in the US partly explain differences in the prevalence of untreated hypertension between these racial/ethnic groups.     

Within- and between-person variation in nutrient intakes of Russian and U.S. children differs by sex and age

Within- and between-person variation in nutrient intake has been characterized in different adult populations, but little is known of country, age, or sex differences among children. The objectives of this study were as follows: 1) to describe the mean intake, within- and between-individual CV and variance ratios of nutrient intake among children ages 9-18 y old in Russia and the United States in 1996; 2) to compare the age and sex-related differences in nutrient intake variance within and between countries; and 3) to hypothesize about the feasibility of using within-individual variance estimates from one nationally representative sample to adjust the usual intake distributions in another nationally representative sample. Mean intakes of all nutrients except magnesium were significantly higher among U.S. children (P < 0.001); within-person variation was higher among the U.S. children, possibly indicating greater access to a wide array of foods. Strong differentials existed in variance components by sex in both countries, although not in the same direction, and differed by age in U.S. girls. Ratios of within- to between-person variance in 8 of 11 nutrients were lower among Russian (range: 0.9-1.6) than U.S. children (range: 1.4-1.7), suggesting that day-to-day bias may not affect Russian dietary recalls as strongly as in the United States. Researchers are encouraged to use these estimates to conduct sensitivity analyses of usual intake distributions in their own data when multiple days of data collection are not feasible.     

Five-year obesity incidence in the transition period between adolescence and adulthood: the National Longitudinal Study of Adolescent Health

BACKGROUND: No nationally representative longitudinal data have been analyzed to evaluate the incidence of obesity in the transition between adolescence and adulthood. OBJECTIVE: The objective was to examine dynamic patterns of change in obesity among white, black, Hispanic, and Asian US teens as they transitioned to young adulthood. DESIGN: We used nationally representative, longitudinally measured height and weight data collected from US adolescents enrolled in wave II (1996; ages 13-20 y) and wave III (2001; 19-26 y) of the National Longitudinal Study of Adolescent Health (n = 9795). Obesity incidence was defined on the basis of International Obesity Task Force (IOTF) cutoffs (wave II), which link childhood body mass index (BMI) centiles to adult cutoffs (BMI > or = 30; wave III), for comparability between adolescence and adulthood. In addition, the more commonly used cutoff of BMI > or = 95th percentile for age- and sex-specific cutoffs from the 2000 Centers for Disease Control and Prevention growth charts for adolescents (wave II) were compared with adult cutoffs (BMI > or = 30; wave III). RESULTS: On the basis of the IOTF cutoffs, obesity incidence over the 5-y study period was 12.7%; 9.4% of the population remained obese and 1.6% shifted from obese to nonobese. Obesity incidence was especially high in non-Hispanic black (18.4%) females relative to white females. The prevalence of obesity increased from 10.9% in wave II to 22.1% in wave III, and extreme obesity was 4.3% at wave III on the basis of a BMI > or = 40. CONCLUSIONS: During a 5-y transitional period between adolescence and young adulthood, the proportion of adolescents becoming and remaining obese into adulthood was very high. This upward trend is likely to continue. Effective preventive and treatment efforts are critically needed.