Location: Children's Nutrition Research Center2010 Annual Report
1a. Objectives (from AD-416)
Childhood obesity is a major public health problem in the U.S. and successful approaches to prevent obesity are needed. The prevalence of overweight in preschool children has more than doubled in the past two decades. Currently, a third of children in the United States are at risk of overweight, while 17% are overweight. A greater concern is that most existing obesity prevention intervention approaches thus far have been found to be largely ineffective. Diverse novel behavioral, genetic, and biological methods and models are needed to better understand the causes and find effective ways to combat this problem. Children's Nutrition Research Center scientists will address these issues through targeting the following research objectives: 1) determine the extent to which relationships between appetite-related genetic factors and dietary intake are mediated by subjective feelings of hunger, satiety, and other psychosocial variables in children; 2) determine the extent to which relationships between activity-related genetic factors and physical activity are mediated by subjective feelings of enjoyment and related psychosocial variables in children; 3) investigate the effectiveness of community-based intervention strategies to prevent childhood obesity and its associated health risks in 8- to 12-y-old Hispanic children with BMI >/= 85th percentile; 4) develop and evaluate family-centered intervention strategies for the pediatric primary care setting to prevent childhood obesity; 5) develop and evaluate the effectiveness of a culturally appropriate, web-based, dietary and physical activity intervention for preventing obesity in high school students; 6) develop and evaluate the effectiveness of novel, multi-media, diet and/or physical activity interventions for preventing obesity in youth; 7) develop and evaluate a model of childhood obesogenic environments based on parent-child dynamics affecting child eating behaviors and body weight status; 8) determine environmental factors and eating pattern typologies associated with obesity and related diseases in children, adolescents, and young adults using extant datasets; 9) identify promising theoretical approaches, mediators, and intervention components of nutrition and physical activity behavior change in children using extant datasets; 10) identify risk factors, moderators, and mediators for obesity and obesity-related behaviors, including dietary, physical activity and lifestyle factors using extant datasets; 11) evaluate relationships between parent and child beliefs about physical activity, and their relationship with child physical activity, sedentary behavior, and weight status using extant datasets; 12) determine obesity-related metabolic and body composition responses to exercise programs with and without a dietary intervention in lean and obese adolescents; and 13) develop and test pilot interventions to increase and sustain physical activity at a level consistent with the Dietary Guidelines for Americans (DG) in urban African- and Mexican-American children and families.
1b. Approach (from AD-416)
A multidimensional approach will be undertaken to address the obesity research conducted at the Children's Nutrition Research Center. In summary, investigators will address childhood obesity through research in genetics, biology, behavioral modeling, and by the implementation of a wide range of interventions. Researchers will investigate the effects of a controlled exercise program alone as compared to exercise with a diet intervention and determine the impact on numerous biological measures of the research participants. Genes related to satiety or physical activity signaling pathways will be examined by researchers as they learn the association of eating and physical activity experiences in children. Additional research will permit new models of how known genes may be influencing diet and physical activity practices. Researchers will develop, test, and validate innovative youth behavioral models and validate a measure of youth physical activity problem solving ability. Additional models will be developed to understand the functional relationships of behavioral factors that influence the weight status of children, as a result of examining parent and child characteristics (individually and combined) to ascertain their contributions to the probability of pediatric obesity. Model refinement will occur by employing dyadic and mixture modeling approaches to account for latent heterogeneity in how these factors are functionally inter-related within the given population. Assessment of the validity of current theories of obesity-related behavior change will be conducted through mediating variable analyses of existing datasets. Several interventions will be conducted in order to establish functional programs that will reduce obesity and/or further weight gain. A family-based randomized controlled trial will be conducted to test the effectiveness of diet behavior modification, structured aerobic exercise, or diet behavior modification plus structured aerobic exercise for obesity prevention and improvement in fitness, health risks, and psychological state in at-risk children. Research studies will also evaluate the effectiveness of a culturally appropriate, web-based, dietary and physical activity intervention for preventing obesity in high school students when compared with a control group. Weight, dietary and physical activity behaviors, and psychosocial mediating variables will be measured and compared to determine the effectiveness of specific web-based interventions. Furthermore, as a result of these interventions, models will be developed and formative work performed to evaluate the developed model for obesity prevention.
3. Progress Report
Project 1. Since cross-sectional studies can lead to flawed inferences, the naturalistic study of influences on obesity/adiposity are best studied in longitudinal designs. However, sufficient changes must occur over time in the dependent variable to have something to predict, and more cost-effective research can be conducted if these changes occur over short time intervals. We generated initial conceptual model that encompasses these possible behavioral, personal, ecological and genetic influences. Project 2. Conducted a family-based intervention to test effectiveness of diet behavior modification with and without exercise for weight loss and improvement in fitness, psychological state, and co-morbidity risk. Also, a 1-yr community-based child obesity intervention called MEND is underway at the YMCA. To explore effect of genetic variation on behaviors related to diet and physical activity, we genotyped 1.1 million single nucleotide polymorphisms (SNPs) in 815 Hispanic children. Data collection is ongoing in the above-mentioned community interventions. We interviewed parents of overweight 5- to 8-year olds for a needs assessment for obesity treatment in primary care. We developed Helping HAND program as a modular 6-month program that targets obesity-related child behaviors and corresponding effective parenting practices. Project 3. All programming for the Teen Choice: Food and Fitness intervention website was completed and the website has been tested. A website for control condition participants was also created. For a 10-episode videogame promoting increased FV, programming for online parent and child data collection questionnaires was finalized. Children and parents are currently participating in the intervention and data collection activities. Recruitment, enrollment, and data collection were initiated for evaluating and refining a hypothesized theoretical model of youth PA behavior. Project 4. Conducted analysis of an existing data set, resulting in submission of two manuscripts for peer review regarding strategies parents use to get children to eat healthy and problems parents encounter with getting children to eat healthy. Presented paper at International Society for Behavioral Nutrition and Physical Activity in June 2010 regarding how emotional climate of the dinner meal may influence eating behaviors of children. Project 5. Conducted continuous data analyses using data from extant datasets. Reviewed parental feeding styles/practices as related to young children's food intake and body weight. Also reviewed adult modeling of dairy foods and its impact on child consumption; characterization of portion sizes; and caregiver attitudes toward portion sizes.
1. Videogame helps children eat fruit and vegetables. Fruit and vegetables have been associated with reduced risk of chronic diseases, such as certain types of cancer. However, today's children eat less than the recommended amounts of fruit and vegetables each day. Setting a goal and making a plan of how to achieve it may be an effective technique for encouraging healthy eating habits. Investigators at the Children's Nutrition Research Center in Houston, Texas, designed a videogame to test this idea; 400 4th and 5th graders enrolled in a study to see if playing the videogame will help them eat more fruit and vegetables. This research will provide insight into ways to develop videogames that help children make healthy choices.
2. MC4R's role in energy expenditure and appetite regulation in Hispanic children. Melanocortin 4 receptor (MC4R) is a protein that binds to a hormone called alpha-melanocyte stimulating hormone (a-MSH) which is involved in eating behavior. Mutations in MC4R constitute the most common form of obesity caused by a single genetic mutation; however, the role that MC4R plays in childhood obesity is unclear. Researchers from the Children's Nutrition Research Center in Houston, Texas, performed studies to identify all possible genetic mutations in MC4R in Hispanic children. Several mutations of MC4R were shown to be associated with physical activity, total energy expenditure and sleeping energy expenditure, and the appetite hormone ghrelin. These novel findings provide strong evidence that this gene likely plays a role in the regulation of weight, not only through food intake but also physical activity. This research contributes to our understanding of the most commonly known genetic defect predisposing children to obesity.
3. Models are not just found on runways. Youth are less physically active than recommended, with continued decreases throughout childhood and adolescence. Theory can help predict, explain, and understand behavior, and provides a blueprint for intervention research; however, there is not a good theoretical model of youth physical activity. Investigators at the Children's Nutrition Research Center in Houston, Texas, have developed a theoretical model that incorporates factors likely associated with youth physical activity. They are currently conducting a study to see if the model predicts physical activity. Ultimately, this research will provide a tested theoretical model of youth physical activity behavior that can be used to guide research to help youth be more physically active.
4. The impact of parent and child characteristics on feeding healthy foods. Since childhood obesity is a significant public health problem, it is important to understand environmental influences on the development of overweight in children. Parents are considered one of the most important environmental influences on the eating behaviors of young children. To evaluate how parent affect and child temperament play a role in how healthy foods are offered to their children, researchers at the Children's Nutrition Research Center, Houston, Texas, used an existing data set to develop measures of strategies parents use and problems encountered in getting their children to eat healthy foods such as fruit and vegetables. Our analyses indicated that a positive parent was associated with feeding strategies and decreased perception of feeding problems. Negative parental affect was associated with increased perception of feeding problems especially when children were negative themselves. Understanding the mechanisms of feeding is important in the facilitation of tailored interventions designed to prevent and reduce overweight in children.
5. Understanding the emotional climate of the dinner meal in Head Start families. Although psychologists have discussed the importance of the emotional climate in parent-child relationships, this has not been studied in a feeding context. To observe differences in the emotional climate created by parents (including affect and other parent behaviors such as tone of voice and gestures) during the dinner meal among low-income families researchers at the Children's Nutrition Research Center, Houston, Texas, compared observed parental measures of positive effect, negative effect, intrusion, and detachment and the influence on feeding. Authoritarian parents (those who expect strict adherence to their directives) were found to be significantly more negative and intrusive with their children during the dinner meal compared to authoritative parents (those who are both responsive and exercise appropriate control) and indulgent parents (those who are highly responsive but do not set boundaries with their children). The uninvolved parents were significantly more detached with their children during the dinner meal compared to authoritative and authoritarian parents and children on average had a higher BMI score of all groups. Results suggest that the emotional climate of the dinner meal may play an important part in how parents socialize their children around eating during mealtime. Results also suggest that parents' self-reported feeding styles may be a proxy for the emotional climate of the dinner meal, which may in turn influence the child's eating behaviors and weight status.
6. Associations among parental feeding styles and children's food intake in limited income families. Although general parenting styles and restrictive parental feeding practices have been associated with children's weight status, few studies have examined the association between feeding styles and outcomes such as children's food intake in multi-ethnic, limited income families. Researchers at the Children's Nutrition Research Center, Houston, Texas, evaluated the association of parental feeding styles and young children's evening food intake in a multiethnic sample of families in Head Start and found that intakes of dairy foods, fruit, juice and vegetables were lowest among children of indulgent or uninvolved parents. These findings suggest that permissive parents feeding styles like indulgent or uninvolved do not promote the intake of nutrient-rich foods fruit, 100% fruit juice, vegetables and dairy foods from 3 PM until bedtime. As a result, interventions may need to be addressed to target parental feeding styles that have the potential to impact children's intake.
7. Parenting practices are associated with fruit and vegetable consumption in preschoolers. Parents may influence children's fruit and vegetable consumption in many ways, but research has focused primarily on counterproductive parenting practices, such as restriction and pressure to eat. To assess the association of diverse parenting practices to promote fruits and vegetables and their consumption among pre-school children, researchers at the Children's Nutrition Research Center, Houston, Texas, performed an analysis on data from 755 Head Start pre-school children and their parents collected in 2004–2005. Researchers found that parents use a variety of parenting practices, beyond pressuring to eat and restrictive practices, to promote fruit and vegetable intake in their young child. Evaluating the use of combinations of practices may provide a better understanding of parental influences on children's fruit and vegetable intake.
8. Caregivers' attitudes regarding portion sizes served to children at Head Start. Head Start caregivers are responsible for educating and feeding preschoolers enrolled in the program, and studies are needed to look at the relationship of portion size served and the association with the intake of those foods in this group of children. To identify the caregivers' attitudes regarding portion sizes served to children at Head Start, researchers at the Children's Nutrition Research Center in Houston, Texas, conducted eight focus groups with Hispanic and African American Head Start caregivers to identify their attitudes regarding amounts and types of foods served to Head Start preschoolers. The caregivers identified child preference, exposure, and pickiness, child age and size, and hunger and the home environment as key influencers on the amounts and types of foods served to Head Start children. Identification of these influencers are important as extension agents should be aware of caregivers' attitudes regarding their influence on child food consumption and teach these caregivers appropriate behavior modeling and affirmation techniques.
9. Characterizing lunch meals served and consumed by preschool children in Head Start using digital photography. Preschool children consume most weekday lunch meals outside of the home, and yet little is known about what is served or consumed. To examine what is served and consumed as the lunch meal by preschool children at Head Start, researchers at the Children's Nutrition Research Center, Houston, Texas, collected three days of lunch intake on preschool children in 16 Head Start centers in Houston using digital photography. Our data showed that the amount of food waste was high; variation in the amounts served and consumed was substantial; and portion amounts served were associated with the amounts consumed. More studies are needed to understand what personal and behavioral factors influence variations in portions served and consumed by preschool children.
10. Active commuting to school and association with physical activity and adiposity. Active commuting to school, i.e., walking or bicycling to school, has shown promise for improving physical activity and preventing obesity in youth. Children's Nutrition Research Center researchers, in Houston, Texas, examined US youth and whether active commuting was associated with moderate-to-vigorous physical activity and decreasing overall fat content. Among participants aged 12-19 years from the US National Health and Nutrition Examination Survey, we learned that active commuting was associated with better BMI scores and skinfolds, and with more moderate-to-vigorous physical activity. Active commuting could have significant population-level impact for physical activity promotion and obesity prevention for US youth. Further studies are necessary, especially well-designed longitudinal studies.
11. Adiposity and association with diet quality among US youth. While energy intake in overweight and obese children has been well documented, few studies have examined overall diet quality. Researchers at the Children's Nutrition Research Center, in Houston, Texas, evaluated the US National Health and Nutrition Examination Survey, and constructed statistical models with the Healthy Eating Index-2005 score as the main outcome variable. Overweight and obese adolescents had significantly lower Healthy Eating Index scores than normal weight adolescents. Besides reducing caloric intake and promoting physical activity, interventions to improve diet quality are warranted for overweight and obese youth.
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