The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study

Prevalence of marked overweight and obesity in a multiethnic pediatric population: findings from the Child and Adolescent Trial for Cardiovascular Health (CATCH) study

OBJECTIVE

Determine the prevalence of marked overweight and obesity among children in the Child and Adolescent Trial for Cardiovascular Health (CATCH), identify high risk groups, and compare findings to other recent studies.

DESIGN

Cohort study.

SUBJECTS/SETTING

Five thousand one hundred-six school children who were participants in CATCH at baseline (age approximately 9 years) during 1991 and 4,019 of those children who had follow-up data from 1994 (age approximately 1 years) available.

METHODS

Body mass index (BMI), triceps and subscapular skinfolds, subscapular to triceps skinfold (S/T) ratio, and an estimate of body fat distribution from skinfolds was calculated. Findings were compared to population-based reference data from the First National Health and Nutrition Examination Survey, 1971 to 1973 (NHANES I), to data from the Bogalusa Heart Study, and to data from the Third National Health and Nutrition Examination Survey, 1988 to 1994 (NHANES III).

RESULTS

Children in CATCH were markedly heavier and fatter than the NHANES I population and more comparable to the NHANES III population, especially those in the upper percentiles. The prevalence of obesity based on BMI and triceps skinfolds >95th percentile among CATCH children was higher in boys than in girls at both baseline (boys 9.1%, girls 8.6%) and follow-up (boys 11.7%, girls 7.2%). It was higher among African-Americans and Hispanics than whites for both sexes. S/T ratios did not differ appreciably from those observed in the NHANES I reference population, suggesting that body fat distribution was more stable over time than BMI and skinfolds.

APPLICATIONS

Our findings support other recent reports that American children, especially African-American and Hispanic children, are becoming heavier and fatter. Preventive measures are warranted, especially for high-risk youth.

A five-year trend of increasing obesity among elementary schoolchildren in multiethnic, low-income, inner-city neighborhoods in Montreal, Canada

OBJECTIVE

To describe the prevalence of overweight and obesity over 5 y among inner-city elementary schoolchildren aged 10-12 y in multiethnic, low-income neighborhoods in Montreal, Canada.

DESIGN

Height and weight of all students in grades 4-6 in 16 control schools participating in an evaluation of the impact of a school-based heart health promotion program, were measured each May/June from 1993 to 1997 in cross-sectional classroom-based school surveys.

RESULTS

The prevalence of overweight (> or = 85th age- and gender-specific percentile for body mass index (BMI) from NHANES I and II) was 35.9% in 1993; it increased by approximately 1.3% per year. The prevalence of obesity (> or = 95th age- and gender-specific percentile for BMI from NHANES I and II) was 15.9% in 1993; it increased by approximately 1.0% per year. In multivariate models predicting overweight and obesity, the odds ratios for year adjusted for age, sex, and family ethnic origin were 1.08 (95% confidence interval (CI), 1.04-1.12), and 1.09 (95%CI, 1.04-1.15), respectively.

CONCLUSION

There were significant secular trends of increasing overweight and obesity among young inner-city schoolchildren from the early to late 1990s. Preventive intervention is clearly indicated because childhood obesity tracks to adulthood and because obesity is associated with substantial morbidity, mortality and health care costs.

Relationship between birth weight and cardiovascular risk factors in Japanese young adults

A number of studies have recently shown a significant inverse relationship between birth weight and incidences of chronic and metabolic disorders such as hypertension and type 2 diabetes, though the findings are not consistent. So far, few investigations have been performed to determine whether this relationship exists in Japanese young adults. We investigated the influence of birth weight on cardiovascular risk factors such as blood pressure and several metabolic variables in Japanese young adults. The data of 299 medical students of Dokkyo University School of Medicine (207 men, 92 women; mean age +/- SD: 23 +/- 2 years) who underwent a medical check-up in 1998 were analyzed. Information on pregnancies and measurements at birth were obtained from The Maternal and Child Health Handbook, which is provided to every pregnant woman by the Ministry of Health and Welfare of Japan. Blood pressure was measured twice in the sitting position using an automated device based on the cuff-oscillometric method. The systolic and diastolic blood pressure in young adulthood was positively correlated with current body weight and body mass index (BMI) in both genders. Although birth weight was not significantly correlated with blood pressure in the young adults examined in the present study, male birth weight was inversely correlated with serum total cholesterol and triglyceride concentrations in young adulthood, independently of current BMI. These results partly support the hypothesis for the first time that low birth weight may be one of the risk factors for subsequent cardiovascular disease in Japanese men.

Updates in pediatric nutrition

There have been many remarkable advances in pediatric nutrition. Solid scientific evidence now supports certain fundamental assumptions long held in the pediatric community. For example, obesity in children has for some time been believed to have adverse health effects; recent large scale studies now confirm relationships between childhood obesity and specific morbidities. Likewise, the beneficial effects of human breast milk on growth and development have been the focus of recent prospective studies of full term and preterm infants. There has been active research in the area of formula intolerance and allergy, allowing practicing physicians to better counsel parents about dietary choices. Although many health problems are caused by the abundance of high fat and high calorie foods in the average US child's diet, a large number of children remain at risk for hunger in the United States. Other research provides important breakthroughs in our understanding of the impact of pediatric nutrition on lifelong health. Retrospective epidemiological studies have uncovered relationships between prenatal factors and health later in life. These studies have lead to ongoing prospective observational trials that should provide further information about the extent to which certain health factors are determined before birth. In addition, basic science research has revealed previously unknown mechanisms by which essential minerals, such as iron, are transported into the body. In sum, this section reviews exciting new information in the areas of childhood diet quality, obesity, breast milk, formula intolerance, and iron metabolism.

Establishing a standard definition for child overweight and obesity worldwide: international survey

OBJECTIVE

To develop an internationally acceptable definition of child overweight and obesity, specifying the measurement, the reference population, and the age and sex specific cut off points.

DESIGN

International survey of six large nationally representative cross sectional growth studies.

SETTING

Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States.

SUBJECTS

97 876 males and 94 851 females from birth to 25 years of age.

MAIN OUTCOME MEASURE

Body mass index (weight/height(2)).

RESULTS

For each of the surveys, centile curves were drawn that at age 18 years passed through the widely used cut off points of 25 and 30 kg/m(2) for adult overweight and obesity. The resulting curves were averaged to provide age and sex specific cut off points from 2-18 years.

CONCLUSIONS

The proposed cut off points, which are less arbitrary and more internationally based than current alternatives, should help to provide internationally comparable prevalence rates of overweight and obesity in children.

Activity, dietary intake, and weight changes in a longitudinal study of preadolescent and adolescent boys and girls

OBJECTIVE

To examine the role of physical activity, inactivity, and dietary patterns on annual weight changes among preadolescents and adolescents, taking growth and development into account.

STUDY DESIGN

We studied a cohort of 6149 girls and 4620 boys from all over the United States who were 9 to 14 years old in 1996. All returned questionnaires in the fall of 1996 and a year later in 1997. Each child provided his or her current height and weight and a detailed assessment of typical past-year dietary intakes, physical activities, and recreational inactivities (TV, videos/VCR, and video/computer games).

METHODS

Our hypotheses were that physical activity and dietary fiber intake are negatively correlated with annual changes in adiposity and that recreational inactivity (TV/videos/games), caloric intake, and dietary fat intake are positively correlated with annual changes in adiposity. Separately for boys and girls, we performed regression analysis of 1-year change in body mass index (BMI; kg/m(2)). All hypothesized factors were in the model simultaneously with several adjustment factors.

RESULTS

Larger increases in BMI from 1996 to 1997 were among girls who reported higher caloric intakes (.0061 +/-.0026 kg/m(2) per 100 kcal/day; beta +/- standard error), less physical activity (-.0284 +/-.0142 kg/m(2)/hour/day) and more time with TV/videos/games (.0372 +/-.0106 kg/m(2)/hour/day) during the year between the 2 BMI assessments. Larger BMI increases were among boys who reported more time with TV/videos/games (.0384 +/-.0101) during the year. For both boys and girls, a larger rise in caloric intake from 1996 to 1997 predicted larger BMI increases (girls:.0059 +/-.0027 kg/m(2) per increase of 100 kcal/day; boys:.0082 +/-.0030). No significant associations were noted for energy-adjusted dietary fat or fiber.

CONCLUSIONS

For both boys and girls, a 1-year increase in BMI was larger in those who reported more time with TV/videos/games during the year between the 2 BMI measurements, and in those who reported that their caloric intakes increased more from 1 year to the next. Larger year-to-year increases in BMI were also seen among girls who reported higher caloric intakes and less physical activity during the year between the 2 BMI measurements. Although the magnitudes of these estimated effects were small, their cumulative effects, year after year during adolescence, would produce substantial gains in body weight. Strategies to prevent excessive caloric intakes, to decrease time with TV/videos/games, and to increase physical activity would be promising as a means to prevent obesity.

Black/white differences in relative weight and obesity among girls: the Bogalusa Heart Study

BACKGROUND AND OBJECTIVE

Although black women have a higher prevalence of overweight and obesity than do white women, it is unclear if a similar pattern exists among youths. We therefore examined the development of black/white differences in relative weight and adiposity among 5 to 17-year-old girls.

METHODS

Cross-sectional analyses of 4542 black and 4542 white girls who were examined between 1973 and 1994. Quetelet Index (kg/m(2)), Rohrer Index (kg/m;s(3)), and height-adjusted weight were used as measures of relative weight, and subscapular and triceps skinfolds as measures of adiposity. Breast development was used as an index of sexual maturation.

RESULTS

On average, black girls were 1 to 3 kg heavier than were similarly aged white girls, and before adolescence, they were 2 to 3 cm taller. After adjusting for differences in height, the mean relative weight of black girls was consistently greater than that of white girls only after age 13; furthermore, sexual maturation was a stronger correlate of relative weight among black girls than among white girls. Comparable differences were seen for the subscapular skinfold thickness, but white girls consistently had a thicker mean triceps skinfold than did black girls.

CONCLUSION

Sexual maturation should be considered in comparisons of relative weight and obesity among youths, and as compared with white girls, black girls do not have a higher mean relative weight until adolescence. The use of different indices of overweight and adiposity can lead to contrasting results, with simple comparisons of Quetelet Index tending to overstate the relative weights of taller children.