Penny Gordon-Larsen

Inequality in the built environment underlies key health disparities in physical activity and obesity.

CONTEXT. Environmental factors are suggested to play a major role in physical activity (PA) and other obesity-related behaviors, yet there is no national research on the relationship between disparity in access to recreational facilities and additional impact on PA and overweight patterns in US adolescents. OBJECTIVE. In a nationally representative cohort, we sought to assess the geographic and social distribution of PA facilities and how disparity in access might underlie population-level PA and overweight patterns. DESIGN, SETTING, AND PARTICIPANTS. Residential locations of US adolescents in wave I (1994–1995) of the National Longitudinal Study of Adolescent Health (N = 20745) were geocoded, and a 8.05-km buffer around each residence was drawn (N = 42857 census-block groups [19% of US block groups]). PA facilities, measured by national databases and satellite data, were linked with Geographic Information Systems technology to each respondent. Logistic-regression analyses tested the relationship of PA-related facilities with block-group socioeconomic status (SES) (at the community level) and the subsequent association of facilities with overweight and PA (at the individual level), controlling for population density. MAIN OUTCOME MEASURES. Outcome measures were overweight (BMI ≥ 95th percentile of the Centers for Disease Control and Prevention/National Center for Health Statistics growth curves) and achievement of ≥5 bouts per week of moderate-vigorous PA. RESULTS. Higher-SES block groups had a significantly greater relative odds of having 1 or more facilities. Low-SES and high-minority block groups were less likely to have facilities. Relative to zero facilities per block group, an increasing number of facilities was associated with decreased overweight and increased relative odds of achieving ≥5 bouts per week of moderate-vigorous PA. CONCLUSIONS. Lower-SES and high-minority block groups had reduced access to facilities, which in turn was associated with decreased PA and increased overweight. Inequality in availability of PA facilities may contribute to ethnic and SES disparities in PA and overweight patterns.

The nutrition transition: worldwide obesity dynamics and their determinants

OBJECTIVE: This paper explores the major changes in diet and physical activity patterns around the world and focuses on shifts in obesity.DESIGN: Review of results focusing on large-scale surveys and nationally representative studies of diet, activity, and obesity among adults and children.SUBJECTS: Youth and adults from a range of countries around the world.MEASUREMENTS: The International Obesity Task Force guidelines for defining overweight and obesity are used for youth and the body mass index ≥25 kg/m2 and 30 cutoffs are used, respectively, for adults.RESULTS: The nutrition transition patterns are examined from the time period termed the receding famine pattern to one dominated by nutrition-related noncommunicable diseases (NR-NCDs). The speed of dietary and activity pattern shifts is great, particularly in the developing world, resulting in major shifts in obesity on a worldwide basis. Data limitations force us to examine data on obesity trends in adults to provide a broader sense of changes in obesity over time, and then to examine the relatively fewer studies on youth. Specifically, this work provides a sense of change both in the United States, Europe, and the lower- and middle-income countries of Asia, Africa, the Middle East, and Latin America.CONCLUSION: The paper shows that changes are occurring at great speed and at earlier stages of the economic and social development of each country. The burden of obesity is shifting towards the poor.

Acculturation and overweight-related behaviors among Hispanic immigrants to the US: The National Longitudinal Study of Adolescent Health

Little is known about the factors underlying the striking increase in overweight occurring between first and second generation US immigrants. Using data from the National Longitudinal Study of Adolescent Health, this study addressed two goals. First, we determined which measures of acculturation (defined as the acquisition of dominant cultural norms by members of a non-dominant group) were important. Second, we determined how the acculturation process affected differences in overweight and its proximate determinants (e.g., physical activity, diet, and smoking) as immigrants acculturated to American society. In addition, we sought to elucidate the role of underlying structural factors (e.g., family income and crime) and acculturation factors (e.g., language spoken at home and proportion of foreign-born neighbors) in generation differences in overweight. Results showed clear structural and acculturation differences between foreign and US-born immigrants to the US. Foreign-born immigrants were more likely to have lower family income and maternal education, and to live in areas of higher immigrant density and greater linguistic isolation. In addition, results suggested rapid acculturation of overweight-related behaviors, such as diet, smoking, and inactivity, in US-born relative to foreign-born immigrants. Multivariate analysis indicated that longer US residence was associated with increased overweight among Puerto Ricans and Cubans. Predicted probabilities showed that controlling for acculturation and proximate factors increased overweight among foreign-born adolescents, but had minimal impact for US-born adolescents. Thus, without the beneficial pattern of: acculturation factors, diet, and physical activity, first generation Hispanic adolescents would have higher overweight prevalence. We found important generation differences in structural, acculturation, and proximate overweight determinants. These lifestyle differences between foreign- and US-born Hispanic adolescent immigrants are likely to underlie the striking increase in overweight prevalence between first and subsequent generation of US residence.

Adolescent physical activity and inactivity vary by ethnicity: The National Longitudinal Study of Adolescent Health ☆ ☆☆ ★

OBJECTIVES To determine the extent to which physical activity and inactivity patterns vary by ethnicity among subpopulations of US adolescents. STUDY DESIGN Nationally representative data from the 1996 National Longitudinal Study of Adolescent Health of >14,000 US adolescents (including 3135 non-Hispanic blacks, 2446 Hispanics, and 976 Asians). METHODS Hours per week of inactivity (TV viewing, playing video or computer games) and times per week of moderate to vigorous physical activity were collected by using questionnaire data. Multinomial logistic regression models of physical activity and inactivity were used to adjust for sociodemographic factors. RESULTS Large ethnic differences are seen for inactivity, particularly for hours of television or video viewing per week (non-Hispanic blacks, mean = 20.4; non-Hispanic whites, mean = 13.1). Physical activity (>/=5 bouts of moderate to vigorous physical activity per week, 5-8 metabolic equivalents) is lowest for female and minority adolescents. Ethnic differences are far greater for inactivity than for moderate to vigorous physical activity. CONCLUSION Minority adolescents, with the exception of Asian females, have consistently higher levels of inactivity. Results vary by sex; males have higher inactivity and physical activity, whereas lowest physical activity is found for non-Hispanic black and Asian females, although Asian females also have low inactivity and low levels of overweight. Overall, efforts to reduce the problem of adolescent overweight should focus on increasing activity levels of adolescents, particularly female, older, and major minority subpopulations.

Environmental influences on food choice, physical activity and energy balance

In this paper, the environment is defined as the macro- and community-level factors, including physical, legal and policy factors, that influence household and individual decisions. Thus, environment is conceived as the external context in which household and individual decisions are made. This paper reviews the literature on the ways the environment affects diet, physical activity, and obesity. Other key environmental factors discussed include economic, legal, and policy factors. Behind the major changes in diet and physical activity in the US and globally lie large shifts in food production, processing, and distribution systems as well as food shopping and eating options, resulting in the increase in availability of energy-dense foods. Similarly, the ways we move at home, work, leisure, and travel have shifted markedly, resulting in substantial reductions in energy expenditure. Many small area studies have linked environmental shifts with diet and activity changes. This paper begins with a review of environmental influences on diet and physical activity, and includes the discussion of two case studies on environmental influences on physical activity in a nationally representative sample of US adolescents. The case studies illustrate the important role of physical activity resources and the inequitable distribution of such activity-related facilities and resources, with high minority, low educated populations at strong disadvantage. Further, the research shows a significant association of such facilities with individual-level health behavior. The inequity in environmental supports for physical activity may underlie health disparities in the US population.

Physical activity and sedentary behavior patterns are associated with selected adolescent health risk behaviors

OBJECTIVE. Little is known about how physical activity (PA), sedentary behavior, and various adolescent health risk behaviors are associated. The objective of this study was to examine relationships between PA and sedentary behavior patterns and an array of risk behaviors, including leading causes of adolescent morbidity/mortality. METHODS. Nationally representative self-reported data were collected (National Longitudinal Study of Adolescent Health; wave I: 1994–1995; II: 1996; N = 11957). Previously developed and validated cluster analyses identified 7 homogeneous groups of adolescents sharing PA and sedentary behaviors. Poisson regression predicted the relative risk of health risk behaviors, other weekly activities, and self-esteem across the 7 PA/sedentary behavior clusters controlling for demographics and socioeconomic status. Main outcome measures were adolescent risk behaviors (eg, truancy, cigarette smoking, sexual intercourse, delinquency), other weekly activities (eg, work, academic performance, sleep), self-esteem. RESULTS. Relative to high television (TV) and video viewers, adolescents in clusters characterized by skating and video gaming, high overall sports and sports participation with parents, using neighborhood recreation center, strict parental control of TV, reporting few activities overall, and being active in school were less likely to participate in a range of risky behaviors, ranging from an adjusted risk ratio (ARR) of 0.42 (outcome: illegal drug use, cluster: strict parental control of TV) to 0.88 (outcome: violence, cluster: sports with parents). Active teens were less likely to have low self-esteem (eg, adolescents engaging in sports with parents, ARR: 0.73) and more likely to have higher grades (eg, active in school, ARR: 1.20). CONCLUSIONS. Participation in a range of PA-related behaviors, particularly those characterized by high parental sports/exercise involvement, was associated with favorable adolescent risk profiles. Adolescents with high TV/video viewership were less likely to have positive risk behavior outcomes. Enhancing opportunities for PA and sport may have a beneficial effect on leading adolescent risk behaviors.

Maturational Timing and Overweight Prevalence in US Adolescent Girls

OBJECTIVES This study examined the relation of age at menarche to overweight in US adolescent girls. METHODS Effects of age at menarche and race/ethnicity on overweight were estimated via logistic regression, after adjustment for sociodemographic characteristics, in a sample of 6507 Hispanic, Black, White, and Asian American girls who participated in wave 2 of the National Longitudinal Study of Adolescent Health. RESULTS Overweight prevalence rates were significantly higher in early maturing adolescents of all racial/ethnic groups but highest (57.5%) among early maturing Black girls. Early maturation nearly doubled the odds of being overweight (body mass index at or above the 85th percentile). CONCLUSIONS Greater public health attention should be focused on the high prevalence of overweight, particularly among minority female adolescents.

Active commuting and cardiovascular disease risk: the CARDIA study.

BACKGROUND There is little research on the association of lifestyle exercise, such as active commuting (walking or biking to work), with obesity, fitness, and cardiovascular disease (CVD) risk factors. METHODS This cross-sectional study included 2364 participants enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study who worked outside the home during year 20 of the study (2005-2006). Associations between walking or biking to work (self-reported time, distance, and mode of commuting) with body weight (measured height and weight); obesity (body mass index [BMI], calculated as weight in kilograms divided by height in meters squared, >or= 30); fitness (symptom-limited exercise stress testing); objective moderate-vigorous physical activity (accelerometry); CVD risk factors (blood pressure [oscillometric systolic and diastolic]); and serum measures (fasting measures of lipid, glucose, and insulin levels) were separately assessed by sex-stratified multivariable linear (or logistic) regression modeling. RESULTS A total of 16.7% of participants used any means of active commuting to work. Controlling for age, race, income, education, smoking, examination center, and physical activity index excluding walking, men with any active commuting (vs none) had reduced likelihood of obesity (odds ratio [OR], 0.50; 95% confidence interval [CI], 0.33-0.76), reduced CVD risk: ratio of geometric mean triglyceride levels (trig(active))/(trig(nonactive)) = 0.88 (95% CI, 0.80 to 0.98); ratio of geometric mean fasting insulin (FI(active))/(FI(nonactive)) = 0.86 (95% CI, 0.78 to 0.93); difference in mean diastolic blood pressure (millimeters of mercury) (DBP(active)) - (DBP(nonactive)) = -1.67 (95% CI, -3.20 to -0.15); and higher fitness: mean difference in treadmill test duration (in seconds) in men (TT(active)) - (TT(nonactive)) = 50.0 (95% CI, 31.45 to 68.59) and women (TT(active)) - (TT(nonactive)) = 28.77 (95% CI, 11.61 to 45.92). CONCLUSIONS Active commuting was positively associated with fitness in men and women and inversely associated with BMI, obesity, triglyceride levels, blood pressure, and insulin level in men. Active commuting should be investigated as a modality for maintaining or improving health.

Screen time and physical activity during adolescence: longitudinal effects on obesity in young adulthood

BackgroundThe joint impact of sedentary behavior and physical activity on obesity has not been assessed in a large cohort followed from adolescence to adulthood.MethodsNationally representative longitudinal data from Waves II (1995; mean age: 15.9) and III (2001; mean age: 21.4) of the National Longitudinal Study of Adolescent Health (n = 9,155) were collected. Sex-stratified multivariate logistic regression analysis assessed the odds of obesity associated with Wave II MVPA and screen time, controlling for sociodemographic characteristics and change in MVPA and screen time from Wave II to III. Obesity was defined using body mass index (BMI, kg/m2) International Obesity Task Force cut-points at Wave II and adult cut-points at Wave III (BMI ≥ 30).ResultsIn males, adjusted odds of prevalent obesity was strongly predicted by MVPA bouts [OR (95% CI): OR6 vs. 1 MVPA bouts = 0.50 (0.40, 0.62); OR4 vs. 40 hrs screen time = 0.83 (0.69, 1.00)]. In females, greater MVPA bouts and lower screen time correlated with lower prevalent obesity [OR (95% CI): OR6 vs. 1 MVPA bouts = 0.67 (0.49, 0.91); OR4 vs. 40 hrs screen time = 0.67 (0.53, 0.85)]. Longitudinally, adolescent screen time hours had a stronger influence on incident obesity in females [OR (95% CI): OR4 vs. 40 hrs = 0.58 (0.43, 0.80)] than males [OR (95% CI): OR4 vs. 40 hrs = 0.78 (0.61, 0.99)]. Longitudinal activity patterns were not predictive of incident obesity.ConclusionReducing screen time during adolescence and into adulthood may be a promising strategy for reducing obesity incidence, especially in females.

Longitudinal trends in obesity in the United States from adolescence to the third decade of life.

No longitudinal analyses using national data have evaluated the increase in obesity from adolescence into early adulthood. We examined obesity incidence, persistence, and reversal in a nationally representative cohort of US teens followed into their early 30s, using measured height and weight data, in individuals enrolled in wave II (1996; 12–21 years), wave III (2001; 17–26 years), and wave IV (2008 early release data; 24–32 years) of the National Longitudinal Study of Adolescent Health (N = 8,675). Obesity was defined as a BMI ≥95th percentile of the 2000 Centers for Disease Control/National Center for Health Statistics growth charts or ≥30 kg/m2 for individuals <20 years and ≥30 kg/m2 in individuals ≥20 years. In 1996, 13.3% of adolescents were obese. By 2008, obesity prevalence increased to 36.1%, and was highest among non‐Hispanic black females (54.8%). Ninety percent of the obese adolescents remained obese in 2008. While annual obesity incidence did not decline in the total sample across the two study intervals (2.3% per year 1996–2001 vs. 2.2% per year 2001–2008), rates among white females declined (2.7 to 1.9% per year) and were highest among non‐Hispanic black and Hispanic females (3.8 and 2.7% per year, 1996–2001 vs. 3.0 and 2.6% per year, 2002–2008, respectively). Obesity prevalence doubled from adolescence to the early 20s, and doubled again from the early to late 20s or early 30s, with strong tracking from adolescence into adulthood. This trend is likely to continue owing to high rates of pediatric obesity. Effective preventive and treatment efforts are critically needed.