Meeting Summary
Agenda and Abstracts
Speaker Roster

What We Know about Obesity Development During Adolescence:
Findings from the NHLBI Growth and Health Study

Sue Y. S. Kimm, M.D., M.P.H., Nancy W. Glynn, Ph.D.
University of Pittsburgh

The Role of Diet and Activity in Obesity Development During Adolescence

The NHLBI Growth and Health Study (NGHS) is a longitudinal study designed to assess factors associated with progressive weight gain and development of obesity in black and white girls during the transition between childhood and young adulthood. NGHS was initiated in 1985 because of the notion that the higher mortality rate from cardiovascular disease was in part explicated by the high prevalence of obesity among African American women. Cross-sectional data indicated that prepubertal black girls were leaner than white girls, but it was during adolescence when the racial divergence in obesity development took place. Thus, the NGHS is a 10-year cohort study of 1213 black and 1166 white girls, aged 9 or 10 at entry, who were followed annually until ages 18 or 19. The follow up rate was 91% for black girls and 88% for white girls.

Racial divergence in adiposity

Puberty was associated with a significant gain in adiposity for both racial groups with the largest gain in adiposity seen at the time of pubescence for both groups, an approximate increase of 8.0 mm of SSF for white girls and 10.8 mm for black girls. At age 9, there were no racial differences in adiposity as measured by the sum of skinfolds (SSF) at the triceps, subscapular and suprailiac sites. Longitudinal regression analysis showed that adiposity for black girls became significantly greater at age 12, after adjusting for pubertal maturation stages. Although the effect of puberty on the gain in adiposity was similar for both races, for each chronological age, there was a greater accrual of adiposity in black girls, because they matured earlier than white girls.

Effect of Dietary Intake and Patterns

Energy intake was significantly higher for black girls at every age, except at age 9 years, with racial differences in the average daily energy intake ranging from 127 kcal at age 10 to 216 kcal at age 17.

At baseline (ages 9 or 10), there was no significant relationship between daily energy intake and adiposity or BMI. However, there was a significant (p<0.01) direct relationship between saturated fat intake and BMI for black girls. For white girls, there was a significant (p=0.002) direct relationship between total fat intake and BMI.

Longitudinal regression analysis revealed that daily caloric intake was inversely associated with adiposity.

Effect of Levels of Physical Activity

Levels of habitual activity (HAQ) were significantly lower in black girls even at ages 9 or 10 (p=0.008). Scores for HAQ declined steadily from baseline until the end of the study, ages 18 or 19. The decline was more precipitous between ages 9 or 10 to 15 or 16. The overall decline in HAQ was 83% for the cohort, but there was a significant racial difference with the decline greater in black girls. Their median HAQ score declined by 100% while that for white girls declined by 64%. The median score for the daily activity scores declined, but not as precipitously as that of HAQ during the same time by 35% for the cohort. At baseline, neither the AD nor HAQ scores were significantly related to adiposity. However, television watching was significantly associated with adiposity in 9 or 10 year old girls when adjusted for energy intake. When the multivariate model included parental education, household income, the number of parents in the household and caloric intake as adjustment variables, television watching was a significant risk factor for obesity only for black and not for white girls. Longitudinal regression analysis revealed a significant (p<0.0001) relationship between BMI and the decline in HAQ after adjusting for race, energy intake, cigarette smoking, age at menarche and childbirth.

References

  1. The National Heart, Lung and Blood Institute Growth and Health Study Research Group. Obesity and cardiovascular disease risk factors in black and white girls: The NHLBI Growth and Health Study. Am J Public Health 1992; 82:1613-1620.
  2. Kimm SYS, Barton BA, Obarzanek E, et al. Racial divergence in adiposity during adolescence: the NHLBI Growth and Health Study. Pediatrics 2001:107 http://www.pediatrics.org/cgi/content/full/107/3/e34.
  3. Kimm SYS, Barton BA, Obarzanek E, et al. Obesity development during adolescence in a biracial cohort: The NHLBI Growth and Health Study. Pediatrics 2002:110 http://www.pediatrics.org/cgi/content/full/110/5/e54.
  4. Kronsberg SS, Obarzanek E, Affenito SG, et al. Macronutrient intake of black and white adolescent girls over ten years: The NHLBI Growth and Health Study. J Am Diet Assoc 2003; 103:852-60.
  5. Obarzanek E, Schreiber GB, Crawford PB, et al. Energy intake and physical activity in relation to indexes of body fat: the National Heart, Lung, and Blood Institute Growth and Health Study. Am J Clin Nutr 1994; 60:15-22.
  6. Kimm SYS, Glynn NW, Kriska AM, et al. Longitudinal changes in physical activity in a biracial cohort during adolescence. Med Sci Sports Exerc 2000; 32:1445-1454.
  7. Kimm SYS, Glynn NW, Kriska AM, et al. Decline in physical activity in black girls and white girls during adolescence. N Engl J Med 2002; 347:718-24.
  8. Kimm SYS, Obarzanek E, Barton BA, et al. Race, socioeconomic status, and obesity in 9- to 10-year-old girls: The NHLBI Growth and Health Study. Ann Epidemiol 1996; 6:266-75.
  9. Kimm SYS, Glynn NW, Barton BA, et al. The association of physical activity with obesity development during adolescence: NHLBI Growth and Health Study. Circulation 2001; 103:1345.
  10. Kimm SYS, Obarzanek EO. Childhood obesity: A new pandemic of the new millennium. Pediatrics 2002; 110:1003-1007.
  11. Kimm SYS, Glynn NW, Aston CE, et al. Effects of race, cigarette smoking, and use of contraceptive medications on resting energy expenditure in young women. Am J Epidemiol 2001; 154:718-24.
  12. Kimm SYS, Glynn NW, Aston CE, et al. Racial differences in the relation between uncoupling protein genes and resting energy expenditure. Am J Clin Nutr 2002;75:714-9.
  13. Kimm SYS, Glynn NW, Obarzanek E et al. Demographic and psychosocial correlates of misreporting of energy intake in a biracial cohort of young women. Am J Clin Nutr 2004 (under revision)

 

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