Trends and Determinants of Childhood and Adolescent Obesity

International Obesity Task Force Findings

- 1 of 10 school-aged children is overweight and obese (155 million) - 2 to 3% obese (30 to 45 million)

Special Issues for Immigrant and Minority Populations

- Among Asians, increased risk associated with obesity shown at lower BMI levels and predisposed to visceral and abdominal obesity compared with Caucasians. - Black and Hispanic youth in USA at greater risk for T2DM compared to white youth. - Caucasian girls often more vulnerable to the psychological effects of obesity compared to other groups.

BMI Cole et al 2000 Cut-Points

- BMI cut-points of 25 (overweight) and 30 kg/m2 (obese) at 18 years and extrapolating these along the equivalent BMI for age percentile lines in a multinational data set of children ages 6-18 years. - Cole cut-points by gender and age in 6-month intervals.

Body Mass Index in Childhood

- BMI in childhood changes substantially with age. - At birth, median is as low as 13 kg/m2, increases to 17 kg/m2 at age 1, decreases to 15.5 kg/m2 at age 6, then increases to 21 kg/m2 at age 20.

International Obesity Task Force (IOTF)

- BMI is the most practical and widely used method for identifying overweight and obesity in children and adolescents. - For international comparisons, the IOTF recommends using BMI cut points by Cole et al, 2000 BMJ.

Why are we worried about childhood obesity?

- Child obesity predicts adult obesity. - Study: Adults who had been overweight as children had an adult BMI 12.4 kg/m2 higher than adults who were non-overweight as children - The connection between adult obesity and disease risk suggests that childhood obesity is also intimately linked to disease. - Obesity increases the risk of CVD - Overt development of CVD occurs beyond 3rd or 4th decade of life, but risk factors can develop early, particularly among overweight children. - Obesity, insulin resistance, dyslipidemia, hypertension confer additive risk for CVD, but absolute importance of each risk factor is unknown (risk assessment evaluated in clusters) - Rise in pediatric obesity has corresponded with increased incidence of pediatric dyslipidemia.

Childhood overweight and obesity rates are on the rise

- Childhood obesity one of the most serious public health challenges. - Problem is global - Steadily affecting many low- and middle-income countries (esp. in urban settings) - In 2010, the number of OW children under 5 is estimated to be > 42 million. - In 2013, 42 million infants and young children were overweight or obese - Worldwide, 70 million young children will be overweight or obese by 2025 if current trends continue.

Generational Gradient Effect of Obesity Among New Immigrants

- Children and adolescence among new immigrants to industrialized countries are more likely to be susceptible to obesogenic environment of host country. - Rising prevalence of overweight from 1st generation (12%), 2nd generation (27%) to 28% of 3rd generation. - Acculturation or assimilation into lifestyles that prevail in industrialized countries plays an important role as a RISK factor for obesity.

Specific Examples of Collective Determinants of Healthy Eating in Childhood: Social (Media)

- Children more likely to request, purchase, consume foods seen on TV - Identified as a factor in the development of overweight. - Identified as a factor in the dieting behaviours of young girls.

Specific Examples of Collective Determinants of Healthy Eating in Childhood: Social (Family)

- Children's dietary patterns evolve within the context of the family. - Intakes of children correlated with parents (mothers) - Positive association between availability and consumption of fruit and vegetables in the home. - Positive association between family meals and increased intake of fruit and vegetables, milk products, calcium, iron, folate and vitamins A, C, E and B6.

Opportunity for Positive Policy Development

- Currently there are a wide variety of definitions of child obesity in use. - The development of an internationally acceptable definition of child overweight and obesity policy is needed. - Specify the measurement, the age and sex specific cut-off points.

Defining Childhood Obesity

- Defining obesity during childhood and adolescence is complicated. - Variability in growth rates and the natural, gender specific variations in body composition that occur during different maturational stages (ie. lots of different 'normals').

Specific Examples of Individual Determinants of Healthy Eating in Childhood: Food Preferences

- Food preferences guided by taste or liking alone - "Dislike for vegetables" an important predictor of fruit and vegetable intake in children. - Personal preferences for eating fast food and vending machine snacks identified as barriers.

Specific Examples of Collective Determinants of Healthy Eating in Childhood: Economic

- Food price: most important when income is restricted (increase selection of high sugar and fat foods). - Low educational status or parents: decreased micronutrient and increased fat intakes. - Maternal employment: negatively associated with frequency of family meals, but positively correlated with diet quality.

Specific Examples of Individual Determinants of Healthy Eating in Childhood: Age/Gender

- Increase in snacking from elementary to higher grades. - Females, particularly adolescents, tend to be at greater nutritional risk vs. males.

Diabetes in Pediatric Populations

- Increasing prevalence in T2DM in pediatric population. - 8 to 45% of new cases of diabetes are in pediatric population (most common in 10-19 years) - 85% of pediatric T2DM population are obese

Specific Examples of Individual Determinants of Healthy Eating in Childhood: Nutrition Knowledge

- Nutrition knowledge low about children and adolescents - Knowledge does not consistently influence dietary behaviour (inter-relationship between knowledge and other determinants may play a factor)

Childhood Obesity and Socioeconomic Status: Novel Role for Height/Growth Limitation Cecil et al. 2005

- Obesity issue is growing in UK from previous data. - Children from a lower socioeconomic household were more likely to be overweight or obese and were shorter than their peers from higher SES households. - Girls were more likely to be overweight/obese than boys in both groups. - The lower income group was 65% more likely than the higher income group to develop obesity.

Facts About Obesity

- Overweight and obese children are likely to stay obese into adulthood and more likely to develop noncommunicable diseases like diabetes and CVD at a younger age. - Overweight and obesity, as well as their related diseases, are largely preventable.

Specific Examples of Collective Determinants of Healthy Eating in Childhood: Physical Environment

- Things like the foods available, portion size and school environment (vending machines, cafeteria) all examples of how the physical environment impacts children's intake. - Children 5+ years of age eat more when served larger portions

BBC Headline "Junk Food Advertisement Code Launched"

- Voluntary restrictions on TV and internet advertising of high fat and sugar foods to children in the UK - Ban TV advertising between 6am and 9pm, all internet. - Ban on unhealthy food promotion in schools: end use of cartoon characters, celebrities, free gifts.

Risk Factors Seen in Children at Unhealthy Weights Include:

- elevated lipids and cholesterol - hypertension - metabolic syndrome - T2DM - liver abnormalities - orthopedic problems - poor peer interaction - depression CVD IS A CONCERN True extent of adverse health outcomes tends to be underestimated. Risk factors have been identified in children as young as 5 years old.

Individual Determinants of Healthy Eating in Childhood

1. Biological factors (age, gender) 2. Food preferences 3. Nutrition knowledge 4. Attitudes

Collective Determinants of Healthy Eating in Childhood

1. Economic 2. Social 3. Physical (environment)

Rising Trends in Canadian Childhood Overweight/Obesity

2004: 26% of Canadian children and adolescents 2-17 years are overweight or obese (up from 15% in 1978/9). Increases were highest among youth (12-17 years old) as overweight/obesity increased from 14% to 29%.