W2005: Parenting, energy dynamics, and lifestyle determinants of childhood obesity: New directions in prevention
Statement of Issues and Justification
Obesity is an epidemic that is occurring even earlier in life than previously observed and impacting children as early as the preschool (ages 2-5) years (Gearhart et al., 2008). Among preschool-aged children, the obesity rate increased from 5% in the 1976-1980 NHANES to 10.4% in the 2007-2008 NHANES (Ogden & Carroll, 2010). While 10.4% of the nation's preschoolers are classified as obese with a body mass index (BMI, kg/m2) at the 95th percentile or higher, more than double that amount (21.2%) are overweight (BMI at the 85th percentile or higher (Ogden & Carroll, 2010). Overall, among children and adolescents aged 2-19 years, approximately 32% are overweight and 17% are obese (Ogden et al., 2010). The increasing number of younger children experiencing weight problems is especially alarming because it places them at risk for chronic diseases (Nelson et al., 2006).The purpose of the proposed 2012-2017 W2005 Multistate Research project is to identify successful childhood obesity prevention strategies that include parenting and to translate those strategies for implementation by community and public health professionals. For young children, parents are role models and gatekeepers for food and physical activity. How can we help the parents provide the environment, support and example needed to help their children achieve a healthy weight? How can we help parents understand the dynamic nature of energy balance, which is impacted by the type and amount of food and physical activity their child receives? These are critical questions that can only be answered by a multistate and multidisciplinary team like the team comprising W2005 which includes experts in nutrition, physical activity, and parenting and child development.
Energy Balance: In the nutrition and physical activity area, energy balance is often used to understand obesity and body weight regulation. In the past, body weight was often described as a simple a balance between energy in and energy out. We now know that the factors that influence body weight are much more complicated. Energy balance is a complex interaction between energy intake, energy expenditure and body storage of energy that all interact to determine ones weight and body composition (e.g. the amount of fat or lean tissue an individual has). Each component of energy balance is influence by genetic and environmental factors. In addition, each component can be influenced by each other. Thus, changing one component can influence the others. For example, changing a childs physical activity can change energy intake by altering appetite either increasing or decreasing depending on the type, amount and intensity of the activity. Thus, our goal is to help parents have a better understanding of how they can positively influence their childs health and body weight relative to body height. These influences can last a lifetime and significantly alter their childrens health as adults. Consequences: Childhood obesity is associated with a variety of immediate and long-term health consequences including psychosocial stress, asthma, sleep apnea, type 2 diabetes, fatty degeneration of the liver (hepatic steatosis), and cardiovascular disease risk factors such as high cholesterol, high blood pressure, and abnormal glucose tolerance (American Academy of Pediatrics, 2003; American Heart Association, 2011; Centers for Disease Control and Prevention, 2011a, 2011b). In addition to the physical consequences, obesity also affects children's psychological well being. Obese children were more likely to be socially isolated (Strauss & Pollack, 2003), had lower self-perceptions, and scored lower on self-worth compared to non-obese children (Braet et al., 1997). Also, overweight and obese children are more likely to become obese adults (Centers for Disease Control and Prevention, 2011b; Nicklas et al., 2001a).
Social and Biological Risk Factors. There are significant racial, ethnic, economic, and gender disparities in the prevalence of childhood obesity (Hudson, 2008; Ogden & Carroll, 2010) and non-Hispanic black girls and Hispanic boys are disproportionately affected (Centers for Disease Control and Prevention, 2011a). According to Hudson (2008), by age 6, the prevalence of obesity is disproportionately higher among black preschoolers than white preschoolers. According to the 2009 Pediatric Nutrition Surveillance System (Centers for Disease Control, 2009a), among low-income preschool children, obesity rates are highest among American Indian or Alaska Native children (20.7%) with other rates as follows: Hispanic (17.9%), non-Hispanic white (12.3%), non-Hispanic black (11.9%), and Asian/Pacific Islander (11.9%) children. Childhood and adolescent obesity rates are highest among non-Hispanic black girls (29.2%) and Mexican-American boys (26.8%), followed by non-Hispanic black boys (19.8%), Mexican-American girls (17.4%), non-Hispanic white boys (16.7%), and non-Hispanic white girls (14.5%) (Ogden & Carroll, 2010). Wang and Beydoun (2007) reported that minority and low-socioeconomic groups are disproportionately affected by overweight and obesity at all ages. According to Seith and Isakson (2011), the gap in overweight between poor and non-poor children is greatest among children in the preschool age range and the gap in obesity is greatest among adolescents aged 12 to 17 years. A much larger percentage (44.8%) of the nation's low-income children (living in households at less than 100% Federal Poverty Level) were overweight or obese in 2007, compared to 22.2% of the nation's higher income children (greater than 400% Federal Poverty Level) (National Initiative for Children's Healthcare Quality, 2007).
A number of factors including genetics, environment, culture, and socioeconomic status contribute to body weight and these factors are thought to interact and influence energy balance, or imbalance resulting in obesity (Centers for Disease Control and Prevention, 2009). The feeding context during early childhood is critical to the establishment of lifelong healthy eating habits (Nicklas et al., 2001b). However, dietary patterns of early childhood often do not follow recommended guidelines (Fox et al., 2010; Kranz et al., 2008). Increases in childhood body weights have largely coincided with changes in diet and consumption patterns, such as increases in portion sizes and energy intake (Nelson et al., 2006). While childhood obesity has been increasing, preschoolers' consumption of fruits, vegetables, and other nutrient-dense foods has decreased resulting in excessive intakes of fat, sodium, and calories in many children's diets (Fox et al., 2010). Reduction and prevention of childhood obesity are national health priorities, and many researchers agree that primary prevention of obesity in childhood is a key strategy for reducing the development of chronic disease and adult obesity (American Academy of Pediatrics, 2003, Dehghan et al., 2005).
Focus on Parenting Risk Factors. While children learn eating behaviors from adults and peers (Jansen et al., 2003), the crucial role of the family in shaping and supporting behaviors leading to healthy weight and preventing child overweight and obesity has been increasingly supported by research investigations since the dearth of such studies was identified in 2000 (IOM, 2000). Since 2000, research has increasingly focused on three aspects of parenting that contribute to children's weight status: general parenting styles, feeding practices, and feeding styles. Parenting style refers to the emotional climate (Darling & Steinberg, 1993) of parent-child interactions that both underlies and transcends specific parenting behaviors (Henry & Hubbs-Tait, 2011). Authoritative (high in responsiveness and high in limits, expectations, and standards), authoritarian (low in warmth and high in parental control), permissive (high in warmth and low in limits), and uninvolved (low in warmth and low in limits and control) parenting styles as well as blends of these styles (Baumrind, Larzelere, & Owens, 2010) are studied in the developmental sciences. Four recent U.S. studies have identified parenting style as a significant predictor of child weight status during the preschool or elementary school years. Two classified children into parenting style categories; two used continuous measures of parenting style. In a sample of 872 children who participated in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development with parenting styles measured in preschool and with child weight measured in first grade, Rhee et al. (2006) found that children of authoritative parents had significantly lower odds of obesity (BMI > 95th percentile) than children of authoritarian, permissive, or neglectful parents, with children of authoritarian parents having the highest odds of obesity. Olvera and Power (2010) found that among 69 Mexican-American 4- to 8-year-old children, those whose mothers were classified as indulgent (i.e., permissive) in parenting style were more likely to have become overweight BMI > 85th percentile and < 95th percentile) 4 years later than their peers whose mothers were authoritarian or authoritative. Chen and Kennedy (2005) reported that continuous parenting style scores that ranged from democratic (permissive) to authoritarian were inversely correlated with continuous BMI in 68 8- to 10-year-old Chinese-American children with lower scores (higher democratic/permissive) associated with higher BMI. Topham et al. (2010) found that 176 mothers' continuous permissive parenting style scores were associated with greater odds of obesity in their first-grade children if the mothers were also depressed or were of higher socio-economic status (i.e., had more economic resources with which to purchase foods). It is important to note that although these four studies of U.S. preschool or elementary school children identified significant links between children's weight status or BMI, three other studies did not (Agras et al., 2004; Gable & Lutz, 2000; Hennessey et al., 2010); two of these studies employed continuous measures of parenting style and one (Hennessey et al.) employed a categorical measure, underscoring the importance of further research, particularly meta-analytic reviews. It is also important to note that of the seven U.S. studies of children in the preschool and elementary school years, the two that focused on obesity (BMI > 95th percentile) found parenting styles to be significantly related to increased odds of obesity either directly (Rhee et al., 2006) or in interaction with other parent or family variables (Topham et al., 2010).
Hughes and her colleagues developed a classification system for parental feeding styles: authoritative, authoritarian, and two permissive feeding styles (indulgent and neglectful) corresponding to general parenting styles (Hughes, Power, Fisher, Mueller, & Nicklas, 2005; Patrick, Nicklas, Hughes, & Morales, 2005). Recent studies of the link of feeding styles to child weight status suggest that the indulgent style is related to higher BMI among preschool (Hughes, Shewchuk, Baskin, Nicklas, & Qu, 2008) and elementary school (Hennessey et al., 2010) children, with the most recent findings replicating these findings among Hispanic preschool boys in Head Start (Hughes et al., 2011).
Feeding practices refer to a wide variety of parental behaviors at snack times or family meals, in purchasing foods, and in eating outside the home. As an illustration of the complexity of current findings we focus first on one feeding practice, restriction. In samples of U.S. preschool and elementary school children, findings on the links between the maternal feeding practice of restriction and children's weight status are varied. Francis, Hofer, and Birch (2001) reported that in a sample of 196 non-Hispanic 5-year old girls and their mothers (104 with BMI > 25), daughters' BMI was positively correlated with mothers' restriction. Similar results were reported by Musher-Eizenman, Lauzon-Guillan, Holub, Leporc, and Charles (2009) for the 59 U.S. mothers of 4 to 7 year old children in this study of both U.S. and French families and for the high-risk for obesity portion of the Infant Growth Study (Faith, Berkowitz, Stallings, Kern, Storey, & Stunkard, 2004). In contrast, no significant association between maternal restriction and child BMI, weight status, or total fat mass was reported in a study of 108 Mexican-American 5th grade children and their mothers (Matheson, Robinson, Varady, & Killen, 2006), in a study of 967 low-income preschool children (May et al., 2007), or in the low-risk-for-obesity portion of the sample of the Infant Growth Study (Faith et al., 2004). Similar to a recent study in the United Kingdom (Webber, Hill, Cooke, Carnell, & Wardle, 2010), a U.S. study that included children ranging in age from 7 to 17 found that parental concern about child weight mediated the link between children's BMI-Z scores and parental restriction with no direct link between parental restriction and child BMI-Z (Gray, Janicke, Wistedt, & Dumont-Driscoll, 2010). These two recent U.S. and U.K. studies suggest that restriction may be a response to concern about child weight status; however, additional research is needed to evaluate whether such a response is effective at preventing child overweight and obesity or promoting healthy child weight.
Other parental feeding practices and more general parenting behaviors are implicated as important in child obesity prevention (Ventura & Birch, 2008). Parents, particularly mothers, are key to developing a home environment that fosters healthful eating among children via several feeding behaviors (Patrick & Nicklas, 2005; Ritchie et al., 2005). Studies have shown relationships between children's food choices and various home environmental factors, such as the influence of television viewing (Coon et al., 2001; Robinson, 2001), the impact of parental feeding practices (Birch & Fisher, 1998), the role of parental modeling (Birch & Marlin, 1982), the effect of food availability and accessibility at home (Baranowski et al., 1998; Baranowski et al., 1999), and the role of family meals (Gillman et al., 2000). Thus a focus on home food environment and parent's role in feeding children provides an important context for developing healthy eating habits and consequently prevention of overweight in children.
In W1005 (2006-2012) we approached childhood obesity prevention in the family context using the concept of resiliency, a characteristic that exists only in a condition of adversity. This concept was applied to families-those living in an environment that promotes obesity, but with children who are not overweight or obese and therefore resilient. We proposed to develop a framework (objective 5) informed by: what is currently being done by practitioners with a concurrent exploration into more useable physical screening tools as well as studies of families with children between the ages of 4-10 years old to distinguish parental behaviors that override the obesogenic environment from those that do not (objectives 1-3). Tools to distinguish between resilient and non-resilient families were to assist in the development of this framework (objective 4). The project team determined that tools exist to identify risk and protective factors for childhood obesity but not to identify resilient families, therefore, resiliency will not be pursued in this proposal. Rather, results from objectives 1-3, along with progress completed on objectives 4 and 5 (focused on parenting that protects from or increases risk of child obesity) will be applied in the new proposal.
Our greatest challenge will be to help the children and adolescents move in to adulthood without carrying the undue burden of obesity and its associated chronic diseases. We do not live in isolation. Children live in families, spend hours in childcare and schools and live and play in communities. How can we train Cooperative Extension specialists and County Agents about the role of parenting related to energy balance? How do parents model good diet and physical activity behaviors as part of a family lifestyle and environment that will help maintain a healthy weight for them and their children?
Integration of Energy Balance and Parenting. Currently, we teach energy balance using a static approach, without understanding the dynamic interplay that occurs between energy intake and expenditure (Hall et al., 2011). Numerous biological and behavioral factors regulate and influence body weight (Galgani & Ravussin, 2008; Hall, et al., 2011; Murphy & Bloom, 2006; Woods & D'Alessio, 2008). Approximately two-thirds of body size is genetically determined, thus, we can only impact the one-third attributed to lifestyle and the environment (Galgani & Ravussin, 2008). Understandably, most education and programming efforts are targeted to the latter. However, to be effective in facilitating sustainable behavior changes, the former must be better understood and appreciated by educators. Further, numerous government programs are aimed at educating about nutrition and/or diet to children and adults, but few have integrated in a meaningful way, the important message of both diet and physical activity. We must identify the most impactful lifestyle and environmental changes that will be most successful in helping children and families manage energy balance and tip the scale toward healthier weights.
Presently, there is no systematic approach that combines what we know about nutrition, healthy eating and physical activity related to energy balance into an integrated approach to teach parents about their role in obesity prevention for their children. One desired outcome of this project is to translate the scientific energy balance evidence and parenting styles into practical and appropriate recommendations for training extension health educators that work with parents.
The new proposal seeks to identify childhood obesity prevention strategies as influenced by parenting, (unique to this proposal) and to provide resources for community and health professionals to use this information in practice.
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