Director, NIH Division of Nutrition Research Coordination National Strategies Concerning Issues of Childhood Overweight and Obesity and Implications for Long-term Health Van S. Hubbard, M.D., Ph.D. CAPT, USPHS Director, NIH Division of Nutrition Research Coordination

Defining Overweight and Obesity: What are the Issues?

weight (kg)/height (m)2 What Is BMI? Body mass index (BMI) = weight (kg)/height (m)2 BMI is an effective screening tool; it is not a diagnostic tool For children, BMI is age and gender specific, so BMI-for-age is the measure used Body Mass Index (BMI) is an anthropometric index of weight and height that is defined as body weight in kilograms divided by height in meters squared. BMI is the commonly accepted index for classifying adiposity in adults and it is recommended for use with children and adolescents. Like weight-for-height, BMI is a screening tool used to identify individuals who are underweight or overweight. BMI is not a diagnostic tool. For example, a child who is relatively heavy may have a high BMI for his or her age or high weight-for-stature. To determine whether the child has excess fat or is overweight, further assessment is needed that might include triceps skinfold measurements, assessments of diet, health, and physical activity. BMI is gender specific for children. Furthermore, whereas a fixed BMI cutoff is used for adults, for children, because BMI changes substantially as they get older, BMI-for-age is the measure used for ages 2 to 20 years.

CDC Growth Charts 2000 Centers for Disease Control and Prevention National Center for Chronic Disease Prevention and Health Promotion Division of Nutrition and Physical Activity Maternal and Child Nutrition Branch The importance of growth charts is well established. They represent a fundamental screening tool for assessing nutritional status in the pediatric population. The new CDC growth charts were released in May 2000 at the National Nutrition Summit. The development of the growth charts was a collaborative effort between the Division of Health Examination Statistics and the Division of Nutrition and Physical Activity (DNPA) at CDC. The new charts are based on a different reference population but they appear similar to the charts that have been in use. The 1977 charts consisted of 14 charts based on age, gender, weight-for-age, length-for-age, height-for-age, weight-for-length, and weight-for-height. The new charts have 16 charts including Body Mass Index (BMI)-for-age for boys and girls aged 2 to 20 years. The addition of BMI-for-age charts are a major change in the revised charts .

Indicators of Nutritional Status in Youth Overweight > 95th percentile of BMI-for-age Risk of overweight > 85th to < 95th percentile of BMI-for-age “Overweight” rather than obesity is the term preferred for describing infants or children greater than or equal to the 95th percentile of weight-for-length or BMI-for-age. The 85th percentile is included on the BMI-for-age and the weight-for-stature charts. Expert committees have indicated that children and adolescents aged 2 to 20 years between the 85th and 95th percentiles are at risk of being overweight. Evaluating a child’s pattern of growth over time is more important than a single measure of size. The pattern of growth is based on periodic measurements which are tracked on a percentile line as a child grows.

Advantages of BMI-for-Age Provides a reference for adolescents that was not previously available Consistent with adult standards so can be used continuously from 2 years of age to adulthood Tracks childhood overweight into adulthood There are several advantages to using BMI-for-age as a screening tool for overweight and underweight. BMI-for-age provides a reference for adolescents that was not previously available. When the 1977 NCHS growth charts were developed, weight-for-height percentiles were provided only for prepubescent girls up to 10 years and for boys up to 11.5 years. Age and stage of sexual maturation are highly related to body fatness. BMI-for-age is the only indicator that allows us to plot a measure of weight and height with age on the same chart. BMI-for-age was not available in the 1977 charts. Another advantage is that BMI-for-age is the measure that is consistent with the adult index so it can be used continuously from 2 years of age to adulthood. These characteristics allow us to use the BMI to track body size throughout the life cycle. BMI in childhood is a determinant of adulthood BMI.

Tracking BMI-for-Age from Birth to 18 Years with Percent of Overweight Children who Are Obese at Age 251 The tracking of BMI that occurs from childhood to adulthood is clearly shown in data from a study by Robert Whitaker (Children’s Hospital Medical Center in Cincinnati) and his colleagues. They examined the probability of obesity in young adults in relation to the presence or absence of overweight at various times during childhood. For example, in children 10 to 15 years old, 10% of those with BMI-for-age < 85th percentile were obese at age 25 whereas 75% of those with a BMI-for-age > 85th percentile were obese as adults and 80% of those with a BMI-for-age > 95th percentile were obese at age 25. (The sample size for the study was 854.) From this study, it is clear that an overweight child is more likely than a child of normal weight to be obese as an adult. Other studies have shown this same trend of tracking occurring from childhood to adulthood. Whitaker et al. NEJM: 1997;337:869-873

Correlation of BMI With Total Body Fat Body Mass Index Adipose Tissue (kg) Zumoff, B et al. J Clin Endocrinol Metab. 1990; 70:929-931.

Obesity Classification for Adults Overweight: BMI > 25 kg/m2 Obesity: BMI > 30 kg/m2 Obesity BMI Class 25.0 – 29.9 Overweight 30.0 – 34.9 Obesity I 35.0 – 39.9 Obesity II > 40.0 Extreme Obesity III NHLBI Guidelines, June 1998

Obesity Trends* Among U.S. Adults BRFSS, 1991, 1995 and 2000 (*BMI  30, or ~ 30 lbs overweight for 5’4” woman) 1991 1995 2000 No Data <10% 10%-14% 15-19% 20% Source: Mokdad A H, et al. J Am Med Assoc 1999;282:16, 2001;286:10.

Prevalence of Overweight and Obesity U.S. Adults, Age 20-74 Years* NHANES II NHANES III NHANES 1976-80 1988-94 1999 n = 1,446 n=11,207 n=14,468 % Overweight or Obese 47 56 61 (BMI > 25.0) % Overweight 32 33 34 (BMI 25.0-29.9) % Obese 15 23 27 (BMI > 30.0) *Age-adjusted by the direct method to the year 2000 U.S. Bureau of the Census estimates using the age groups 20-34, 35-44, 45-54, 55-64, and 65-74 years.

Prevalence of Overweight* Among U.S. Children and Adolescents *Gender- and age-specific BMI > the 95th percentile Source: Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS)

Degree of risk increases with degree of overweight Slide of Risk Classification algorithm

Risk influenced by Regional Fat Deposition and Degree of Visceral Adiposity Apples/pears slide picture of MRI insulin resistant Waist circumference

Obesity and Mortality Risk

Mortality Rate Associated with Obesity Obese individuals have a 50 to 100% increased risk of death from all causes, compared with normal-weight individuals. Most of the increased risk is due to cardiovascular causes.

Obesity and Hypertension Risk % Systolic > 140 mm Hg BMI Levels Canadian Guidelines for Healthy Weights. Cat No. H39-134/1989E; 1988:69.

Obesity and Diabetes Risk Incidence New Cases per 1,000 Person-Years BMI Levels Knowler WC, et al. Am J Epidemiol. 1981;113:144-156.

Weight Gain and Diabetes Risk Weight Change Since Age 21 Relative Risk Body Mass Index at Age 21 Chan JM, et al. Diabetes Care. 1994; 17:960-969.

Overarching Purpose: TO CALL THE NATION’S ATTENTION TO THE EPIDEMIC OF OVERWEIGHT AND OBESITY AND IDENTIFY ACTIONS THAT WE AS A NATION CAN UNDERTAKE

Overweight and Obesity: A Public Health Priority Prevention or intervention to improve health Need to be aware of social, cultural, and environmental influences Must have access to family and community support Everybody must do their share

Obesity is a Chronic Disease Often treated as a “subacute” illness, in which time-limited treatment will lead to a complete cure

Genetics Humans have evolved genes favoring energy intake and storage. 20-40% of Obesity Is Due to Genetic Factors Humans have evolved genes favoring energy intake and storage. 70+ loci, genes, or markers may be involved in causing a susceptibility to obesity.

Prevention and Intervention Strategies Modification toward more healthful lifestyles Increase “purposeful” activity Decrease sedentary behaviors Improve dietary choices Use available support mechanisms

Issues Influencing Behavioral Change Appropriateness of messages Reading level Racially/ethnically correct Scientifically sound

Issues Influencing Behavioral Change Consistency of messages Motivation to adopt modified behavior Availability of appropriate and accessible options or choices

Who Should Be Involved? Families Schools Businesses Health care organizations Communities Media

Families and Communities Cultural and environmental influences Access to safe activity Access to support mechanisms

Schools Food Service Activity Health Education Pricing Vending machines Activity General Intramural Varsity Health Education

Worksite Support of infrastructure for families and communities Data on work efficiency Value for the money Wellness programs

Health Care Awareness (early identification) Access Training Reimbursement Acceptance of chronic disease model

Media and Communications Improve recognition and translation of what is important Media emphasizes conflict Conflicts often presented without appropriate filter Terminology Success stories

Why Should Groups Work Together? Efficiency and common resources Many groups are consulting with the same experts Many groups are seeking support from the same sources Many goals are overlapping Improved consistency of efforts

Monitoring Our Status Leading Health Indicators within Healthy People 2010 – Annual Report Card Subpopulations Measured versus self-report Cross-sectional versus longitudinal Modification of health risks

Summary Life-long modification of behaviors will be needed Prevention is the ultimate goal for those who are not overweight Improvement in health risk is the goal for all Everyone needs to become a Partner

Paul Ambrose

Let us all strive to make a difference