Definition of Obesity
� Obesity is commonly defined with reference to:
�body mass index: wt(kg)/ ht2 (m)
What is BMI?
•Body mass index (BMI) is a practical measure used to determine overweight and obesity.
•BMI is the most widely accepted method used to screen for overweight and obesity in children and adolescents because
•It is relatively easy to obtain the height and weight measurements needed to calculate BMI
•Measurements are non-invasive•BMI correlates with body fatness
•BMI it is not a diagnostic measure because BMI is not a direct measure of body fatness.
Body Mass Index (BMI)
� A common measure expressing the relationship (or ratio) of weight-to-height
� A mathematical formula◦ weight (kg) / [height (m)]2
◦ weight (lb) / [height (in)]2 x 703
BMI-for-age weight status categories and the
corresponding percentiles for children are shown
in the following table.
Weight status category Percentile range
Underweight Less than the 5th percentile
Healthy weight 5th percentile to less than the 85th percentile
Overweight 85th to less than the 95th percentile
Obese Equal to or greater than the 95th percentile
Causes of Childhood Obesity
Modifiable causes:� Sedentary behavior� Socioeconomic status� Eating habits� Environment
Non-changeable causes:� Genetics
Environmental Influences on Overweight Children
1. The Family Eating Environment2. Household Food Insecurity 3. Changes in the Food Environment4. Physical Inactivity5. School Physical Education6. School Food Environment
7. Television Viewing
Why is childhood obesity a concern?� Leading cause of pediatric hypertension
� Associated with type II diabetes� Increases the risk of CHD� Increases stress on the weight-bearing joints
� Lowers self esteem� The economic cost of obesity in the United States was about $117 billion in 2000.
1999
Obesity Trends* Among U.S. AdultsBRFSS, 1990, 1999, 2009, 2010
(*BMI ≥≥≥≥30, or about 30 lbs. overweight for 5’4” person)
1990
No Data <10% 10%–14% 15%–19% 20%–24% 25%–29% ≥30%
2009
2010
2008 Estimates of the Percentage of Adults† Who Are Obese in Oregon
Centers for Disease Control and Prevention: National Diabetes Surveillance System. Available online at: http://apps.nccd.cdc.gov/DDTSTRS/default.aspx. Retrieved 9/7/2011.
Prevalence of Obesity* Among U.S. Children and Adolescents
(Aged 2–19 Years)
Survey Periods
NHANES I
1971–1974
NHANES II
1976–1980
NHANES III
1988–
1994
NHANES
2003–2004
Ages
2 through 5
5% 5% 7.2% 13.9%
Ages
6 through 11
4% 6.5% 11.3% 18.8%
Ages
12 through 19
6.1% 5% 10.5% 17.4%
*Sex-and age-specific BMI ≥ 95th percentile based on the CDC growth charts
From CDC: http://www.cdc.gov/nccdphp/dnpa/obesity/childhood/prevalence.htm
Trends in Childhood Overweight
Age (in
years)1
NHANES
1963-1965
1966-19702
NHANES
1971-1974
NHANES
1976-1980
NHANES
1988-1994
NHANES
1999-2000
NHANES
2001-2002
NHANES
2003-2004
NHANES
2005-2006
NHANES
2007-2008
Total (3) 5.0 5.5 10.0 13.9 15.4 17.1 15.5 16.9
2-5 (3) 5.0 5.0 7.2 10.3 10.6 13.9 11.0 10.4
6-11 4.2 4.0 6.5 11.3 15.1 16.3 18.8 15.1 19.6
12-19 4.6 6.1 5.0 10.5 14.8 16.7 17.4 17.8 18.1
Prevalence of obesity among U.S. children and adolescents aged 2-19,
for selected years 1963-1965 through 2007-2008
History of BMI Screening at Bethel
� 2005: All K-5 students (community-researchers-schools)
� 2006-7: Grades K, 3, and 5 (school staff)
� 2008- 12: All K-5 students (CAST-school collaboration)