5. INTRODUCTION TO OBESITY CYCLE
_____________________________________________________________
Sandy Hassink, MD
A.I. Dupont Institute
Nemours Children’s Hospital
Thomas Jefferson University
Wilmington, DE
_____________________________________________________________
Pre-Test Questions (detail explanations at the bottom):
Q1. In the past 20 years, the prevalence of obesity in childhood has
a. Decreased by about 10%
b. Remained about the same
c. Increased to over 10%
d. Increased to over 15%
Q2. What percentage of children in the United States is now considered to be overweight or obese?
a. 15 %
b. 30 %
c. 45 %
d. 60 %
Q3. True or False. This epidemic should be seen as purely environmentally induced.
Q4. What individual, family, community or societal factors are involved?
a. food costs
b. Food insecurity
c. Availability of fast food
d. Parental concerns for undernutrition
e. All of the above
Q5. How does this effect individual patients? List 4 consequences
a. ________________
b. ________________
c. ________________
d. ________________
OBJECTIVES
On completion of this introduction, residents and physicians will:
1. Appreciate the rising prevalence of obesity among children in the United States
2. List environmental and metabolic factors likely to contribute to this phenomenon
3. Appreciates that obesity is felt to be polygenic in nature with genetic and metabolic predisposition triggered by an obesity-promoting environment.
4. Identify metabolic consequences of obesity in childhood as they affect adult health
5. Appreciate the necessity of complete engagement of the child, family and community in the prevention and treatment of obesity in childhood.
Facilitator Preperation:
These four references provide an overview of the increasing prevalance of obesity. The modules that follow will address consequences. A complete set of references is at the end of the module.
1. Center for Health Statistics, Centers for Disease Control and Prevention. Prevalence of Overweight Among Children and Adolescents; United States, 1999-2000. www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm
2. Podem CL, Flegal KM, Carroll MD, Johnson CL: Prevalence and trends in overweight among US children and adolescents 1999-2000 JAMA 288:1728-32,2002
3. Wang G, Dietz W. Economic burden of obesity in youths aged 6 to 17 years: 1979-1999. Pediatrics. 2002 May; 109(5): E81-1. Erratum in: Pediatrics 2002 Jun; 109(6): 1195.
4. Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting obesity in young adulthood from childhood and parental obesity Engl J Med 1997; 337(13): 869-73.
5. Drewnowski A, Specter S. Food costs and energy content. Am J Clin Nutr 2004; 79: 6-16.
INTRODUCTION
The epidemic of obesity has presented an increasing burden of illness in a young adult/adult population. More young parents are chronically ill with an impact on their children. There is an increased burden on the health care system, economics, time and personnel as well as an increased economic burden on the larger economy and health of the population. The modules in Section 3 that follow in the Teacher’s guide address specific concerns using case-based learning to stimulate learner participation in the process. This introduction brings our salient features of the obesity epidemic setting the stage for engagement with children, their families and the problems they bring with them when “at-risk’ for overweight or actually obese.
Prevalence: In 2000, over 15% of 6-19 year olds or almost 9 million children in the United States were overweight. This prevalence occurs across the full spectrum of ages and is similar for 12 to 19 year olds. The incidence is rising rapidly for 2 to 5 year old children among whom there were 10% whose weight was >95% for age and gender. (1).
Obesity effects all children but there are disproportional effects among minority children. In 1998, 21.5 percent of African American children, 21.8 percent of Hispanic children and 12.3 percent of Caucasian children had a Body Mass Index (BMI) greater than the 95%percentile for age and gender. (2) Several tribal groups of Native American children have been particularly affected.
The impact of heredity: The genetic predisposition toward obesity is undeniable. Families with one or both parents who are obese are at increased risk for having an obese child and adolescent. (4) Obese individuals may have an inherited susceptibility to positive energy balance and/or a mechanism for enhanced fat storage as more calories are stored as fat. Adoption studies found a high correlation between obesity in adopted children and their biologic parents. Twins reared together or apart have similar rates of obesity. Hypertension, obesity, adult diabetes and hyperinsulinemia cluster in families. Children in these families may already have increased insulin, lipids and blood pressure.
There are more that 200 genes or gene markers associated with obesity and multiple genetic mechanisms for inheritance. Most human obesity is polygenic and the development of obesity is thought to be a result of gene/environment interaction. Genes influence susceptibility, environment influences outcome.
The impact of poverty: Endemic poverty among children of all backgrounds may be as important to their subsequent obesity as their heredity, ethnicity, or culture, per se. Low birth weight sets a trigger for obesity later in life. Both the stress and actuality of intermittent abundance and deprivation. lack of exercise, and a compelling sense of deprivation fire the gun. Food insecurity in itself, almost universal for poor families truing to survive without support for food or rent, leads to metabolic and cultural responses to deprivation. Obesity is one consequence for those families living at the fringe of complete deprivation and a sense of security for the availability of necessities such as food, housing, and health care.
This is well illustrated by the differences in prevalence of obesity at different income levels. The poorest families in the United States, those living with incomes below the poverty level, have a child obesity rate of 12%. The rate for families with incomes between one and three times poverty level have a rate of 22%. With sufficient and secure incomes of greater than three times the poverty level, the child obesity rate falls to 12% again. (Hofferth and Curtin) The lower rate for obesity in the poorest families, however, is associated with specific nutrient deficiencies and is not associated with healthfulness. The underlying cause is the remarkable affordability of high energy, low nutrient density foods as compared to the cost of high nutrient density foods. (Drewnowski)
Immediate consequences: Obesity and obesity related co morbidities account for an increasingly large number of hospitalizations. Discharge diagnosis for diabetes, obesity, sleep apnea, and gallbladder disease are up 15-74%over the past 2 decades (3) Annual hospital costs for obesity related diagnosis have risen over the past 2 decades (in 2001 dollars) from $35 million (0.43% of total hospital costs during 1979–1981 to $127 million (1.70%of total hospital costs) during 1997–1999. (3)
Long-term consequences: Obesity can be thought of as an accelerator of adult disease. Obese children already have both risk factors and evidence of chronic disease. Pediatricians must engage in prevention of obesity and be prepared to identify and treat these co morbid diseases in childhood. Comorbidities of childhood obesity include the spectrum of insulin resistance, impaired glucose tolerance, and dysmetabolic syndrome and type 2 diabetes. Obstructive sleep apnea is common and results in impaired concentration; memory problems and learning difficulties and can include severe hypoxia, hypercarbia and apnea during sleep. Fatty infiltration of the liver can progress through nonalchoholic steatoheapatitis to cirrhosis. Polycystic ovarian syndrome can begin in adolescence with the precursor of premature adrenarche and present with irregular menses, hirsuitism, and acanthosis nigricans, Orthopedic problems unique to children are serious and include slipped capital femoral epiphysis and Blount’s disease. Pseudotumor cerebri is more common in obesity and can present with headache, vomiting and papilledema resulting in visual field cuts and blindness if untreated. Obesity related emergencies are becoming increasingly more common; these emergent situations include hyperosmolar hyperglycemic state, pulmonary emboli, diabetic ketoacidosis and cardiomyopathy of obesity.
The impact of activity: Activity/inactivity patterns form early in childhood. Preschool children from obese/overweight families preferred sedentary activity. (5) Various factors may be involved in this trend toward decreasing activity. Children may lack activity opportunities in daycare; activity may be episodic and not sustained. Older caregivers tend to be more inactive, multiple caregivers may not coordinate the child’s activity level, the level of obesity increases with increased television and computer time, safety issues determine the level of outdoor activity for many children. The family’s activity level will influence the child’s activity level. Activity is an important modifiable factor in energy regulation Dietary change should be accompanied by changes in physical activity and inactivity.
Increased physical activity cannot only modify obesity but also the associated comorbidities. It can lower blood pressure, may lower lipids levels, decreases metabolic syndrome, increases bone mineral density, and increases fitness. Most people do not realize the activity equivalent of their calorie intake. A person weighing 65kg will burn 5.2-kcal/min walking and only 1.4 kcal/min sitting. With a typical juice or snack costing 150kcal. (6). Populations at risk for low physical activity are also at risk for obesity these include females, children of lower socioeconomic status and lower education, minority ethnic populations, children living in the northeast and south, and children with disabilities.
Obesity is associated with deconditioning and impaired bioenergetic capacity of skeletal muscle mitochondria. Insulin resistance causes dysregulation of oxidation of carbohydrate and lipid fuels decreasing oxidoreductase activity and increased triglyceride storage in muscle.
The impact of “tube watching:” There is a direct relationship between obesity and hours spent watching TV and other forms of “tube watching.” The average teen watches 22 hrs TV/week. It is also not unusual to have 6-8 hours/day of electronic media involvement per day. Parents often consider this normal. Teens often “don’t know what to do” if not watching TV or computer. They may not have or have thought of any other activity opportunities.
Modest changes are effective: It is important to note that modest increases in energy not compensated by activity can result in large weight gain over time. In a child predisposed to weight gain an increase of 150-kcal/d excess intakes per day can result in a weight gain of 15lbs/year. Common causes of increased caloric intake in childhood and adolescence include increased snacking, consumption of high calorie beverages, increased portion sizes, and consumption of fast food.
Preventive steps: It is necessary to recognize the importance of the social environment. That part of the environment that is distal from the life of the family and community is “macro-social.: Though usually unrecognized by family or provider, how a family pays for food, where they feed their children, and public policies towards providing food have an enormous effect on the prevalence of obesity if not so much on which children are obese. The specificity of the problem (which child, which family) is affected by the micro-social environment described below. Effective interventions address large issues of food availability for the poor. Otherwise, successfully treating one child will simply leave dozens of others to take his pr her place.
A developmental approach to obesity prevention is essential because patterns of eating and feeding, satiety and hunger are fostered at each developmental stage. Multi generational and family based patterns of eating and feeding are also influenced by cultural and societal norms.
Breast-feeding is has been found to exert a modifying effect on the incidence of obesity. A large crosses sectional study of breast fed vs formula fed infants showed a clear dose response relationship between breastfeeding and obesity. (7) Breast fed infants has been found to regulate total energy intake before and after introduction of solid food. (8) Another large study of breast-fed and formula fed infants showed decreased body fat in breast fed vs. formula fed infants (Darling Study). (9)
Families need to be integrally involved with obesity prevention and intervention. The structuring of meals, portions sizes, use of beverages as food, use of food for reward, comfort or relief of boredom, child’s access to food and inconsistent family responses to demands for food are all behaviors, which need to be examined and possibly changed.
Adolescents have particular nutritional challenges when it comes to obesity prevention and treatment. For example 25% of adolescents do not meet any requirement for food group intake. Forty five percent of adolescents meet one or less of recommended food group intake. Only 1% met all food group recommendations but had highest energy from fat. Over 90% of adolescents eat snacks but only 39% of adolescents’ report eating nutritious snacks. Snacks provide up to one third of adolescents’ daily energy intake. Meal skipping is common, particularly breakfast skipping. Adolescents may be using diet supplements, unusual diets or fasting in an effort to address their concerns about weight.
Schools are also venues for lifestyle learning and change but physical education time has been reduced, snack machines account for a major source of excess calories for adolescents. Peer pressure and teasing can create a hostile atmosphere and result in depression and low self esteem in obese children.
Families need to be involved in the nutritional and activity changes necessary to prevent and treat obesity. Incremental change at a pace the family/adolescent can accomplish is most useful. Families need help identifying priorities for change, identify setbacks and solutions, and in developing proactive strategies to maintain lifestyle changes.
Families need to work on day to day consistency, consistency between households, between weekdays and the weekend and between the normal nutritional and activity routine and vacation and planning for times of individual or family stress. Family based approach-using parents as the sole agent of change resulted in improved risk factors for both parents in addition to the child. (10). Adults need to take charge of the nutritional/activity environment at the family, community and societal levels.
As health care providers we should be aware that small changes can make a large impact on a child and families risk of obesity and related diseases.
REFERENCES
1. Center for Health Statistics, Centers for Disease Control and Prevention. Prevalence of Overweight Among Children and Adolescents; United States, 1999-2000. www.cdc.gov/nchs/products/pubs/pubd/hestats/overwght99.htm
2. Strauss RS, Pollack HA. Epidemic increase in childhood overweight, 1986-1998. JAMA 2001 Dec 12,286(22) 2845-8.
3. Wang G, Dietz W. Economic burden of obesity in youths aged 6 to 17 years: 1979-1999. Pediatrics. 2002 May; 109(5): E81-1. Erratum in: Pediatrics 2002 Jun; 109(6): 1195.
4. Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting obesity in young adulthood from childhood and parental obesity Engl J Med 1997; 337(13): 869-73.
5. Wardle J, Guthrie C, Sanderson S, Birch L Ptomin R: Food and activity preferences in children of lean and obese parents. Int J Obes Relat Metab Disord 2001 Jul25 (7): 971-7.
6. Cradle, Exercise Physiology Phila 1981
7. Von Kries R, Koletzko B, Sauerwald T, von Mutius E, Barnert D, Grunert V, von Voss H. Breast feeding and obesity: cross sectional study. BMJ. 1999 Jul 17; 319(7203): 147-
8. Evaluation of Infant Growth (An). WHO Working Group on Infant Growth (WHO/NUT/94.8). English, 1994. Document produced by the WHO Division on nutrition, ISBN:
9. Dewey KG, Heinig MJ, Nommsen LA, Peerson JM, Lonnerdal B. Breast-fed infants are leaner than formula-fed infants at 1 y of age: the DARLING study. IS J Clin Nutr? 1993 Feb; 57(2): 140-5.
10. Golan M, Crow S. Targeting parents exclusively in the treatment of childhood obesity: long-term results. Obes Res. 2004 Feb; 12(2): 357-61.
11. Podem CL, Flegal KM, Carroll MD, Johnson CL: Prevalence and trends in overweight among US children and adolescents 1999-2000 JAMA 288:1728-32,2002
12. Hofferth SL, Curtin S. Food programs and obesity among US children. http://www.gwu.edu/~labor/papers/hofferth.pdf
13. http://obesity1.tempdomainname.com/subs/fastfacts/obesity_youth.shtml
14. Dietz WH, (2005) Childhood Obesity (in) Modern Nutrition in health and Disease., 10th edition. Shils, ME, et al (eds) Williams Wilkins Lippincott, Baltimore, MD.
Annotated Answers:
A1. The answer is C. There has been an inexorable shift in energy balance over the past 20 years. Though criteria have changed (weight/height to BMI percentiles) there is no doubt that these past years have seen an overwhelming increase in the percentage of children considered obese. The prevalence rates of childhood and adolescent obesity are rising and steadily increasing. Over 10% of children ages 2-5 are overweight compared to 5% in 1980
A2. The answer is C. According to the American Association of Obesity "Approximately 30.3 percent of children (ages 6 to 11) are overweight and 15.3 percent are obese. For adolescents (ages 12 to 19), 30.4 percent are overweight and 15.5 percent are obese." The data vary for unique population. In New York City, over 50% of children from poorer families are overweight or obese.
A3. The answer is False. Obesity is polygenic in nature with genetic and metabolic predisposition triggered by an obesity-promoting environment. No single factor should be considered as a cause in isolation from others. Multiple environmental factors ranging from food costs and insecurity to parental concerns interact with metabolic factors including heredity and the quality of the in-utero environment to affect weight of children and adults.
A4. The answer is E. As noted above, the obesity epidemic is a result of multiple interacting factors in the "macro-social" (out of sight or unknown and distant the family) environment and "micro-social (proximal and easily appreciated) environment. One must never see proximal without considering the impact of the distal. Doing so invariably leads to blaming the victim. Various worries about undernutrition will contribute to overnutrition.
A5. The answer is: Obesity has increased the prevalence of "traditionally" adult diseases in the pediatric population. Here's a short list: Type 2 Diabetes Mellitus, hypertension, dyslipidemia, liver disease, sleep apnea/upper airway obstruction and various orthopedic disabilities..
