What is childhood obesity?

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Having a body mass index (BMI) at or above the 95th percentile for children of the same age and sex. Rapid changes from infancy through adolescence are part of normal and expected development, and the norm used to identify childhood obesity must be correct for that child’s age and sex.
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Causes and Symptoms

A chronic or recurrent imbalance between energy expended (how active one is) and energy ingested (how much one eats and drinks) will lead to overweight and obesity, which have short- and long-term impacts on health outcomes. When ingestion regularly exceeds expenditure, the unused energy is stored in adipose tissue, or body fat. From an evolutionary standpoint, animal species that developed the capacity to store fat had a better chance of surviving times of scarcity. Chronic storage of excessive energy, as commonly occurs when levels of physical activity are less, produces its own physical pathology. Almost every person who eats and drinks more than he or she uses in energy (usually calculated in calories) will produce adipose tissue to store the excess energy.

Peptide hormones such as leptin and adiponectin regulate and balance energy expended with energy ingested. When leptin is absent (leptin deficiency), massive obesity is present; this condition improves when people are given leptin. Adiponectin, the most abundant hormone in fat cells, is also an insulin sensitizer and an anti-inflammatory signaler. Leptin and adiponectin, along with other peptide hormones, initiate a series of signaling processes that eventually lead to signaling hormones that turn on the food-seeking abilities of organs and muscles.

There is no international consensus on clinically meaningful cutoffs for the classification of overweight and obese children. Commonly used criteria include 110 to 120 percent of ideal weight for height; weight-for-heigh z-scores of > 1 and > 2; and the 85th, 90th, 95th, 97th percentiles for body mass index (BMI), which is calculated by dividing weight in kilograms by square of height in meters squared. The American Medical Association Expert Committee recommendations suggest that a BMI that is equal to or greater than the 85th percentile but less than the 95th percentile for sex and age is considered overweight; a BMI equal to or greater than the 95th percentile for sex and age is considered obese; and a BMI equal to or greater than the 99th percentile is considered severely obese.

Childhood obesity has many detrimental effects and comorbidities (associated diseases and disorders) that often extend into adolescence and adulthood. It is simplistic to say that obese children will become obese adults. Still, childhood obesity often produces a metabolic syndrome that greatly increases the risk that the individual will remain obese into adolescence and adulthood. This syndrome has serious implications for quality of life and life expectancy. Metabolic syndrome is a combination of high insulin levels (hyperinsulinemia), obesity, high blood pressure (hypertension), and abnormal lipid levels (dyslipidemia). Metabolic syndrome initiates a process that leads to an excess of insulin production that, in turn, promotes high blood pressure and dyslipidemia. Together, these produce aortic and coronary atherosclerosis (hardening of the arteries) and clogging of the arteries by fatty deposits in the blood. According to the US Centers for Disease Control and Prevention, obese children are more likely to have risk factors for cardiovascular disease, such as high cholesterol (hypercholesterolemia) or high blood pressure (hypertension). Obese adolescents are more likely to have prediabetes, a condition in which blood glucose levels indicate a high risk for the development of diabetes.

Genetic factors play a fundamental role in childhood obesity, as genetically obese families illustrate. People cannot exchange the genes that they have inherited, but environmental factors are also important, as they are the only ones where weight management is possible.

The psychosocial impact of childhood obesity is no less serious than physical syndromes, leading to poor body image, low self-esteem, social isolation, recurrent anger, early forms of eating disorders, clinical depression, and negatively acting-out in school and other social settings. Promoting physical activity is an important intervention to lessen the psychological harm of obesity as much as is controlling the amount and type of food and drink.

Treatment and Therapy

The most effective treatment for child obesity is prevention, and it can begin shortly after birth. Research shows that breast-fed children have significantly lower rates of obesity in later years. All children must gain weight as they grow, and having an adequate amount of fat cells during early antenatal development is critically important for maximal growth of key organs. Baby fat is important; its absence is problematic. As infants become toddlers and toddlers become children, the difference between healthy weight gains and weight gains that suggest the onset of obesity often require the expert eye of a pediatrician or family physician. A healthy five-pound weight gain in one five-year-old child may not be healthy in another child of the same age.

It is not until adolescence that children play a significant role in choosing and purchasing food. Until then, whatever children eat is most likely what adults have purchased or provided. Preventing obesity and correcting it when it occurs requires thoughtful selection of food and beverage items at home and school. Fast and take-out foods are always an easy solution to busy, hectic family schedules, but they are almost always obesity-promoting. Junk food snacks, also a quick solution to the transient hunger pangs of youth, are similarly harmful.

Prevention and treatment are almost one and the same in dealing with child obesity. Parents control the food of children, and making available a variety of healthy choices becomes an important part of achieving and maintaining healthy bodies that have modest amounts of adipose tissue, as children with a BMI of less than 20 are underweight and also unhealthy. Obesity is much less likely to occur in families and schools that support healthy lifestyles: balanced nutritional consumption, physical activity and exercise, and sufficient sleep. (As a group, children who consistently get less sleep than they need are more likely to be obese than are children who sleep enough. The specific number of hours any child might need is a function of several factors, including age.)

Successful school-based interventions in the management of obesity include a prioritization of physical education classes, healthy choices on the student menu and in vending machines, proportional servings, encouraging water as the main beverage, and the ready availability of after-school activities that involve physical activity, such as intramural sports. When these elements are not present, effective weight management for school-age children is difficult.

The key to successful long-term obesity prevention and treatment involves awareness of and respect for the individual child’s personal preferences and enjoyments—nothing will enhance motivation more. Decreasing sitting time and the active encouragement of free play is far more effective than mandates to exercise or reduce food intake. Even in families where genetics play a major role in obesity, a healthy lifestyle will decrease the negative impact that obesity can have on the children’s overall health.

Perspective and Prospects

According to the Centers for Disease Control and Prevention (CDC), the percentage of children aged six to eleven years in the United States who were obese increased from 7 percent in 1980 to nearly 18 percent in 2012, and the percentage of adolescents aged twelve to nineteen years who were obese increased from 5 percent to nearly 21 percent over the same time period. Although a national study by the CDC showed that obesity among low-income preschoolers declined in nineteen states between 2008 and 2011, childhood obesity remains an epidemic that has achieved the status of a public health crisis. According to the World Health Organization (WHO), in 2010, forty-three million children (thirty-five million in developing countries) were estimated to be overweight or obese, and an additional ninety-two million were at risk of becoming overweight. The WHO estimates that the worldwide prevalence of childhood overweight and obesity increased from thirty-two million globally in 1990 to forty-two million in 2013. At this rate, the WHO predicts that by 2025, the number of obese infants and young children will rise to seventy million.

Obesity has profound impacts on children’s long-term physical and psychological health and, more often than not, leads to serious comorbidities in adulthood that are costly to treat and difficult to control. Focused strategies on modifying behavior and the slow but steady acquisition of healthy habits are the only ways that children will reliably manage the balance between calories consumed and calories burned. Adult habits, good and bad, are usually fostered during childhood. They reflect the level of care, attention, and perseverance of caregivers. Childhood obesity can be a problem of adults’ mismanagement much more than it is a problem of children’s choices. Parents, caregivers, and teachers make a major contribution to children when they provide a health-oriented environment in which children are more likely to acquire the habits that promote wellness throughout their lives.

In 2010, First Lady Michelle Obama began the national "Let's Move!" campaign to comprehensively fight the childhood obesity epidemic within a generation. The program aimed at increasing physical activity and education for children, ensuring better nutrition in school lunches, and providing more information to parents to aid in healthy eating practices. Not long after its inception, President Barack Obama signed the Healthy, Hunger-Free Kids Act into law. This act called for reforms in school lunch programs nationwide, including setting new nutritional standards for the food served at lunch and in vending machines. As part of the campaign's fifth birthday, the First Lady included exercise and dance activities in 2015's annual Easter egg roll event at the White House. As of that year, debates still ensued over whether the program was having any direct effect on the epidemic. Critics cited statistics that continue to show that too many American children are still struggling with obesity.


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