Obesity in the Early Childhood Years: State of the Science and Implementation of Promising Solutions

Prevalence and Trends of Early Childhood Obesity

On average, children in the United States have gained weight since the early 1970s, observed Cynthia Ogden epidemiologist at the National Center for Health Statistics at the Centers for Disease Control and Prevention (CDC). Based on growth charts prepared by the World Health Organization and CDC, Ogden described that in 2011–2012 the prevalence of high weight-for-recumbent length (a weight-for-recumbent length above the 95th percentile on the CDC growth chart) in children less than 2 years of age in the United States is between 7 and 8 percent, with a higher prevalence for girls than boys. Among children 2 to 5 years old, according to data presented by Ogden from the National Health and Nutrition Examination Survey, obesity (a BMI at or above the 95th percentile on the CDC growth chart) has risen from approximately 5 percent in the early 1970s, when existing body mass indexes (BMIs) were used to establish a baseline for obesity, to 8.4 percent—9.5 percent for boys and 7.2 percent for girls in 2011–2012. The percentage of 2- to 5-year-olds who are overweight (a BMI at or above the 85th percentile and below the 95th percentile on the CDC growth chart) is 14.4 percent overall, with an approximately equal distribution for boys and girls. Ogden explained that differences in these numbers between ethnic and racial groups become prominent by 2 to 5 years of age, with the numbers higher among Hispanic and African American children than among white and Asian children. Among 2- to 19-year-olds in the United States, the prevalence of obesity has tripled—to more than 15 percent—from the 1970s to 2011–12, the most recent data available, Ogden reported. However, obesity trends were essentially flat over the decade before the most recent data, meaning that the increases occurred largely in the 1980s, 1990s, and the first few years of the 2000s (see Figure 1). Furthermore, for 2- through 5-year-olds, over the period from 2003–2004 to 2011–2012, the prevalence of obesity decreased from 13.9 percent to 8.4 percent, though Ogden stated that more data are needed to confirm this drop. This significant decline was only seen in this age group. A number of studies found an association between childhood obesity and adult obesity, Ogden pointed out at the end of her presentation. These studies leave many questions unanswered about the persistence of obesity into adulthood, but suggest that it becomes more likely if the child ages at an unhealthy weight.

Epigenetics

Shari Barkin William K. Warren Foundation Chair and Professor of Pediatrics at Vanderbilt University, described one of the intriguing new areas of research that have a bearing on childhood obesity: the science of epigenetics. Epigenetics refers to how the environment may affect the expression of genes by influencing how they are expressed in different tissues and at different times. For example, maternal and paternal nutrition both affect the expression of genes in children. A mother’s high-fat diet during pregnancy can alter a child’s gene expression related to lipid metabolism, glucose metabolism, and appetite, which in turn can affect the phenotype of that child. Further study of epigenetics could direct attention to factors in the environment that are modifiable, Barkin observed. Research on gene expression also could indicate which children are at risk, and potential mechanisms that could increase or decrease that risk.

Food Preferences

Julie Mennella, a member at the Monell Chemical Senses Center in Philadelphia, described some of the ways in which our food preferences are shaped by our evolutionary heritage and by the foods to which we are exposed early in life. Babies are born with an attraction to the sweet taste of mother’s milk. During times of growth children also are attracted to other sweet tastes, such as fruit, which signal energy. However, in the current food environment, the elegant biology that attracts children to mother’s milk and to calories makes them vulnerable to obesity. Sensory experiences beginning early in life can modify flavor and food preferences, Mennella pointed out. With repeated tastings of a food and extended experiences with food variety, children can learn to eat healthier foods. Yet many families are not eating healthy foods, so children may have little exposure to them. Mennella pointed to interventions before conception or the birth of a child as a time when parents are motivated to change long-established patterns of behavior as well as interventions that not only focus on the child, but also include the parents or family. Similarly, as taste and flavor preferences begin to change in adolescence, teens can be encouraged to improve their diets before they become parents themselves.

Interventions that begin in the first two years of life and continue over time have the potential to reduce childhood obesity, continued Taveras. In a review of interventions implemented in the first 2 years of life, the interventions that worked demonstrated an effect primarily by focusing on individual- or family-level behavior changes and in homes, clinical settings, or community-based settings. However, the effects of the interventions tended to be short term, suggesting that repeated interventions will be needed to sustain benefits over time.

Although there is limited study of interventions of children 2–5 years of age in the clinical setting, pediatricians have a number of advantages in reaching out to children and families, including access to children and parents or guardians and the ability to link families to information and community resources, noted Ian Paul, professor of pediatrics and public health sciences at the Pennsylvania State University College of Medicine, chief of the Division of Academic General Pediatrics, and vice chair of clinical affairs in the Department of Pediatrics at Penn State Hershey Children’s Hospital. To prevent and treat obesity, pediatricians can identify children at risk, educate families, shape the food and activity environment, and encourage self-monitoring in families. New models of care could give pediatricians more time with families and enable them to partner with other health care professionals to prevent or treat obesity in children 2–5 years of age.

Early care and education is another setting in which service providers can do more to prevent obesity in young children. The experiences children have in these settings can affect diet, physical activity, and general health outcomes, observed Dianne Ward, professor of nutrition at the University of North Carolina’s Gillings School of Global Public Health. The community context, organizational policies and practices, and interpersonal relationships with parents and care providers all can promote healthy eating and regular physical activity.

Finally, interventions in the home setting focused on healthy lifestyle behaviors (e.g., timing of introduction of solids, limiting sugar sweetened beverages, repeated exposures to vegetables, parent and diet and physical activity modeling), parenting skills (e.g., responsive parenting, child emotion regulation), and broader family life (e.g., child school readiness, targeting child conduct disorder) can be effective in reducing BMI and have been particularly successful in working with low-income and racial and ethnic minority groups, said Kirsten Davison, associate professor of nutrition at the Harvard School of Public Health. However, as with many of the interventions discussed at the workshop, Davison stressed that results tend to be short-term, and the interventions need to be reinforced in order to achieve sustained effects.

The programs of the U.S. Department of Agriculture address food security and nutrition in a variety of ways, observed Kevin Concannon, the department’s undersecretary for Food, Nutrition, and Consumer Services. Programs such as the Special Supplemental Nutrition Program for Women, Infants, and Children; the Supplemental Nutrition Assistance Program; the Child and Adult Care Food Program; and the Dietary Guidelines for Americans approach the issues of obesity prevention in a variety of ways and through the involvement of a variety of partners, such as health care organizations and systems. Furthermore, these programs have the potential to do more, said Concannon, through partnerships with a wider range of state, local, and private sector organizations.

New York City is an example of a locality that has taken decisive, multifaceted steps to address obesity, said Jeni Clapp, director of healthy eating initiatives at the New York City Department of Health and Mental Hygiene. A range of initiatives that have focused on improving the environments in which people live, including interventions in stores, restaurants, marketing, schools, child care settings, and individual neighborhoods, has contributed to a plateauing or decline of obesity in recent years among New York City children, especially those at high risk for being overweight or obesity.

The Nemours Children’s Health System is an example of a health care organization that has taken a multifaceted approach to obesity prevention and treatment, stated Allison Gertel-Rosenberg, director of national prevention and practice in the Nemours National Office of Policy and Prevention. It has sought to complement and expand the reach of clinicians using a community-based approach in which messages regarding healthy eating and physical activity extend across the lifecycle with consistent messaging from parents, early care and education providers, and physicians. In this way, the system serves as an integrator that works intentionally and systematically across sectors to improve health and well-being.

Finally, Terry Huang, professor at City University of New York School of Public Health, offered three lessons that he has learned through his extensive cross-sectoral work on obesity prevention. First, building trust between partners takes time, resources, effort, and strategy, but it is essential for multisectoral approaches. Second, effective leadership makes it possible to leverage collaboration and competition, both of which are important in changing the outcomes of complex systems. Third, the goals of systems continually need to be reassessed and reset, which in turn will reveal new questions, new strategies, and new ways to understand and affect those systems.