The role of built environments in physical activity, eating, and obesity in childhood

Over the past forty years various changes in the U.S. "built environment" have promoted sedentary lifestyles and less healthful diets. James Sallis and Karen Glanz investigate whether these changes have had a direct effect on childhood obesity and whether improvements to encourage more physical activity and more healthful diets are likely to lower rates of childhood obesity. Researchers, say Sallis and Glanz, have found many links between the built environment and children's physical activity, but they have yet to find conclusive evidence that aspects of the built environment promote obesity. For example, certain development patterns, such as a lack of sidewalks, long distances to schools, and the need to cross busy streets, discourage walking and biking to school. Eliminating such barriers can increase rates of active commuting. But researchers cannot yet prove that more active commuting would reduce rates of obesity. Sallis and Glanz note that recent changes in the nutrition environment, including greater reliance on convenience foods and fast foods, a lack of access to fruits and vegetables, and expanding portion sizes, are also widely believed to contribute to the epidemic of childhood obesity. But again, conclusive evidence that changes in the nutrition environment will reduce rates of obesity does not yet exist. Research into the link between the built environment and childhood obesity is still in its infancy. Analysts do not know whether changes in the built environment have increased rates of obesity or whether improvements to the built environment will decrease them. Nevertheless, say Sallis and Glanz, the policy implications are clear. People who have access to safe places to be active, neighborhoods that are walkable, and local markets that offer healthful food are likely to be more active and to eat more healthful food-two types of behavior that can lead to good health and may help avoid obesity.     

Aetiology of overweight and obesity in children and adolescents

The epidemic diffusion of obesity in industrialised countries has promoted research on the aetiopathogenesis of this disorder. The purpose of this review is to focus mainly on the contribution that European research has made to this field. Available evidence suggests that obesity results from multiple interactions between genes and environment. Parents obesity is the most important risk factor for childhood obesity. Twin, adoption, and family studies indicated that inheritance is able to account for 25% to 40% of inter-individual difference in adiposity. Single gene defects leading to obesity have been discovered in animals and, in some cases, confirmed in humans as congenital leptin deficiency or congenital leptin receptor deficiency. However, in most cases, genes involved in weight gain do not directly cause obesity but they increase the susceptibility to fat gain in subjects exposed to a specific environment. Both genetic and environmental factors promote a positive energy balance which cause obesity. The relative inefficiency of self-adapting energy intake to energy requirements is responsible for fat gain in predisposed individuals. The role of the environment in the development of obesity is suggested by the rapid increase of the prevalence of obesity accompanying the rapid changes in the lifestyle of the population in the second half of this century. Early experiences with food, feeding practices and family food choices affect children's nutritional habits. In particular, the parents are responsible for food availability and accessibility in the home and they affect food preferences of their children. Diet composition, in particular fat intake, influences the development of obesity. The high energy density and palatability of fatty foods as well as their less satiating properties promotes food consumption. TV viewing, an inactivity and food intake promoter, was identified as a relevant risk factor for obesity in children. Sedentarity, i.e. a low physical activity level, is accompanied by a low fat oxidation rate in muscle and a low fat oxidation rate is a risk factor of fat gain or fat re-gain after weight loss. Conclusion Further research is needed to identify new risk factors of childhood obesity, both in the genetic and environmental areas, which may help to develop more effective strategies for the prevention and treatment of obesity.     

Effects of manipulating sedentary behavior on physical activity and food intake

OBJECTIVES: Sedentary behaviors have been correlated with obesity. We investigated whether changes in sedentary behaviors relate to changes in energy intake and/or physical activity. STUDY DESIGN: Experimental within-subject crossover design in which children participated in three 3-week phases: baseline and increased and decreased targeted sedentary behaviors. PARTICIPANTS: Thirteen 8- to 12-year-old, nonobese children. MEASUREMENTS: Sedentary behaviors were measured through the use of daily activity logs, physical activity measured with accelerometers, and energy intake measured by means of repeated 24-hour recalls collected during each phase. Energy intake, energy expenditure, and energy balance per day were calculated. RESULTS: Children showed significant (P <.001) increases of 50% and decreases of 53% in targeted sedentary behaviors from baseline during the increase and decrease phases, respectively. There was a significant (P =.05) increase in energy balance per day (+350.7 kcal) when sedentary behaviors were increased, as the result of an increase in energy intake per day (+250.9 kcal) and a decrease in energy expenditure (-99.8 kcal). No significant changes in energy balance were observed when sedentary behaviors were decreased. CONCLUSIONS: Increasing sedentary behaviors had a greater influence on physical activity and energy intake than reducing sedentary behavior in nonobese youth. In some children, changes in sedentary behaviors may be important to modify energy balance and prevent obesity.     

Energy balance: an overview with emphasis on children

Childhood obesity is a significant public health problem, affecting one in five children in the United States. At the crux of this issue is a dysregulation of energy intake and energy expenditure. This review will provide an overview on energy and nutrient balance. We discuss energy balance studies in children using indirect and direct measures, and focus particularly on obesity as a deleterious consequence in childhood survivors of cancer. Obesity affects 11-57% of children with acute lymphoblastic leukemia, probably due to increased energy intake and reduced energy expenditure secondary to reduced habitual activity caused by fatigue. However, most of the studies in children with leukemia are retrospective, use BMI as a measure of obesity, and are inconclusive about the impact of the type of treatment on the development of obesity later in life. To better understand the etiology of obesity in both healthy and sick children, we need to undertake nutrient balance studies with appropriate measures of fat mass and fat distribution while keeping in mind the influence of normal tissue growth and puberty on energy balance.     

儿童肥胖与维生素D缺乏

儿童肥胖和维生素D缺乏已成为两大公共卫生问题.近年来大量研究表明肥胖及其相关的代谢性疾病与血清低维生素D水平相关,但维生素D缺乏与肥胖之间的因果关系仍不明确.目前仍没有足够证据证明维生素D补充对改善体重、体块指数及脂肪量有益.肥胖可能导致了低维生素D状态,而维生素D和维生素D受体则可能通过作用于脂肪分化、脂肪细胞凋亡、脂质合成和分解、摄食行为及能量消耗方面影响能量平衡.     

Television's influence on children's diet and physical activity

Understanding the impact of TV on children's diet and physical activity is important for developing strategies to prevent obesity and sedentary lifestyles. Determining parents' perceptions of television's influence on children's dietary intake and physical activity may provide useful information on this important topic. A questionnaire was developed to assess viewing habits and child requests for food and sport items advertised on TV. It was administered to 66 mothers of children, ages 3-8. Foods that children requested because they had seen them on TV paralleled the frequencies with which these foods were advertised on TV. Weekly viewing hours correlated significantly with (a) reported requests by children and purchases by parents of foods influenced by TV, and (b) children's caloric intake. Children's requests for sport items and physical activities were not significantly correlated with the number of hours of TV viewing. It appears from these data that parents perceive that television influences family purchasing patterns through the mechanism of their children's requests.     

The nutritional cost of measles in Africa.

A 24 hour energy balance study was carried out on 20 black Kenyan children with acute measles and repeated after recovery. The energy content of a weighed 24 hour food intake and of a simultaneous collection of faeces and urine was determined by bomb calorimetry. Energy expenditure was measured by indirect calorimetry using a purpose built flow over calorimeter. The nutritional state of the children was assessed by anthropometry at the time of each study and during convalescence. The results showed a fall of roughly 75% in the intake of gross and metabolisable energy during measles, while the resting energy expenditure was little affected. Thus the severe degree of negative apparent energy balance observed during measles is the combined effect of underfeeding in ill children, and failure, during starvation related to infection, of the early fall in metabolic rate that characterises simple underfeeding.     

Genetics and the pathophysiology of obesity

Obesity is a complex disease that involves interactions between environmental and genetic factors. Obesity results from an imbalance between food intake and energy expenditure over several years. The genetic approach both in animal models and in humans has allowed immense progress in the understanding of body weight regulation. Monogenic forms of obesity in humans have been characterized and result from mutations in genes involved in the central pathways of food intake regulation. However, these cases are extremely rare and generally obesity must be considered as a complex polygenic disease involving interactions between multiple genes and the environment. Numerous studies, including studies in children, have tried to identify "susceptibility" genes. At present, the results are not conclusive inasmuch as they are highly variable between studies and because the relative risk associating a specific gene allele and obesity remains low. Thus, it seems highly premature to genotype obese patients on a large scale for predictive testing. When specific pharmacological treatments based on recent discoveries become available, however, genetic testing could help discriminate between the subtypes of obesity that may respond differentially to treatment.     

Adipositas im Kindesalter Ursachen und Therapiemöglichkeiten

Background. There is twice as much obesity in the world as 20 years ago. About 20% of children and youth are overweight or obese in Germany. New pathophysiologic knowledge and general treatment of obesity in children will be described with an interest of a practical use. Pathophysiology. Regulation of bodyweight takes place as well in central nervous system as in the periphery. Different hypothalamic centers for hunger and satiety correspond to molecular transmitter-systems. There may be a dysbalance of energy intake and energy expenditure caused by a reduced energy expenditure. Regarding this there exist actual genetic findings, too. As this recent pathophysiologic knowledge isn't able to explain the increase in prevalence, psychosocial factors will be regarded as well. Therapy. To be appropriate to this complexity, an efficient treatment has to consist of diet, nutritional education, behavioural therapy and physical activity. Individual needs have to be taken in consideration under medical supervision and in the given social environment.     

Neuroendocrine regulation of food intake

Maintenance of appropriate stores of metabolic fuels depends on carefully matching caloric intake to caloric expenditure. Achieving such 'energy balance' is a product of complex interactions of peripheral hormones with effector systems in the central nervous system (CNS) that regulate food intake and energy expenditure. Leptin is a hormone that is made in the adipocytes, circulates in the blood and interacts with receptors in the CNS. These receptors can be found in two different types of systems. One effector system is termed 'anabolic' and is activated by low levels of leptin during negative energy balance. This system (exemplified by the hypothalamic neuropeptide Y system) increases food intake and decreases energy expenditure to facilitate the regaining of lost energy stores. The other effector system is termed 'catabolic' and is activated by high levels of leptin during positive energy balance. This system (exemplified by the hypothalamic melanocortin and corticotrophin-releasing hormone systems) decreases food intake and increases energy expenditure to facilitate the loss of excess energy stores. Further understanding of these systems is necessary to develop adequate treatments for disorders of energy balance, such as obesity and wasting.     

The role of schools in obesity prevention

Mary Story, Karen Kaphingst, and Simone French argue that U.S. schools offer many opportunities for developing obesity-prevention strategies by providing more nutritious food, offering greater opportunities for physical activity, and providing obesity-related health services. Meals at school are available both through the U.S. Department of Agriculture's school breakfast and lunch programs and through "competitive foods" sold a la carte in cafeterias, vending machines, and snack bars. School breakfasts and school lunches must meet federal nutrition standards, but competitive foods are exempt from such requirements. And budget pressures force schools to sell the popular but nutritionally poor foods a la carte. Public discomfort with the school food environment is growing. But can schools provide more healthful food options without losing money? Limited evidence shows that they can. Although federal nutrition regulations are inadequate, they permit state and local authorities to impose additional restrictions. And many are doing so. Some states limit sales of nonnutritious foods, and many large school districts restrict competitive foods. Several interventions have changed school food environments, for example, by reducing fat content of food in vending machines and making more fruits and vegetables available. Interventions are just beginning to target the availability of competitive foods. Other pressures can also compromise schools' efforts to encourage physical activity. As states use standardized tests to hold schools and students academically accountable, physical education and recess have become a lower priority. But some states are now mandating and promoting more physical activity in schools. School health services can also help address obesity by providing screening, health information, and referrals to students, especially low-income students, who are at high risk of obesity, tend to be underinsured, and may not receive health services elsewhere.     

Neuroendocrine regulation of food intake

Seeley RJ, Schwartz MW. Neuroendocrine regulation of food intake. Acta Pædiatr 1999; Suppl 428: 58–61. Stockholm. ISSN 0803–5326
Maintenance of appropriate stores of metabolic fuels depends on carefully matching caloric intake to caloric expenditure. Achieving such'energy balance'is a product of complex interactions of peripheral hormones with effector systems in the central nervous system (CNS) that regulate food intake and energy expenditure. Leptin is a hormone that is made in the adipocytes, circulates in the blood and interacts with receptors in the CNS. These receptors can be found in two different types of systems. One effector system is termed'anabolic'and is activated by low levels of leptin during negative energy balance. This system (exemplified by the hypothalamic neuropeptide Y system) increases food intake and decreases energy expenditure to facilitate the regaining of lost energy stores. The other effector system is termed'catabolic'and is activated by high levels of leptin during positive energy balance. This system (exemplified by the hypothalamic melanocortin and corticotrophin-releasing hormone systems) decreases food intake and increases energy expenditure to facilitate the loss of excess energy stores. Further understanding of these systems is necessary to develop adequate treatments for disorders of energy balance, such as obesity and wasting. □ Corticotrophin-releasing hormone, energy balance, food intake, leptin, melanocortin, neuropeptide Y     

Role of dietary factors and food habits in the development of childhood obesity: a commentary by the ESPGHAN Committee on Nutrition

This Comment by the Committee on Nutrition of the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition aims to provide a summary of the role of nutrition-related factors on obesity prevention in children ages 2 to 18 years. This Comment emphasizes that dietary interventions should be incorporated into a multidisciplinary strategy for obesity prevention. No single nutrient has been unequivocally associated with the development of obesity. Methodological limitations in study design and the complex nature of obesity must be taken into account when interpreting the association with reported dietary factors. Energy intake should be individually determined, taking into account energy expenditure and growth. Preferential intake of slowly absorbed carbohydrates and limiting the ingestion of rapidly absorbed carbohydrates and simple sugars should be promoted. No specific recommendations for macronutrient intakes to prevent obesity can be made. Plant foods can be used as the main food contributors to a well-balanced diet with adequate monitoring of nutrient intake. Plain water should be promoted as the main source of fluids for children instead of sugar-sweetened beverages. Children should eat at least 4 meals, including breakfast, every day. Regular family meals should be encouraged. Regular consumption of fast food with large portion sizes and high energy density should be avoided. Healthy food options should be promoted for snacking. Food portion sizes should be appropriate for age and body size. Nutrition and lifestyle education aimed at the prevention of obesity should be included in the routine care of children by health care professionals.     

Obesity: a growing problem

Obesity, defined as a body mass index (BMI) of 30 kg/m2 or more, is common in many parts of the world, especially in the established market economies, the former socialist economies of Europe, Latin America, the Caribbean and the Middle Eastern Crescent. As many as 250 million people worldwide may be obese (7% of the adult population) and two to three times as many may be considered overweight. The prevalence of obesity seems to be increasing in most parts of the world, even where it used to be rare. Increased fatness, measured by a high BMI, a large waist circumference or a high waist/hip circumference ratio, is associated with many chronic diseases as well as with poor physical functioning. Assessments of the prevalence of obesity, and trends in this prevalence over time, are more difficult in children than adults, due to the lack of international criteria for classifying individuals as overweight or obese. The World Health Organization has now recommended the use of BMI-for-age percentiles, but the reference curves are still under development. France. The Netherlands, the UK and the USA are among the countries that have reported recent increases in the prevalence of obesity in children and adolescents. Although there are no accurate estimates of the components of energy balance and their changes over time, the available evidence suggests that the trends in obesity rates are related more to a reduction in energy expenditure than to an increase in caloric intake. Prevention of obesity through the promotion of a healthy lifestyle is among the important challenges for the new millennium, and should start in childhood.     

Food advertising to children and its effects on diet: review of recent prevalence and impact data

In the context of a global obesity epidemic that has led to an unprecedented burden of non‐communicable disease, the role of food and beverage marketing to children has been scrutinised in numerous studies. This article discusses the broader concept of an obesity‐promoting food environment, before reviewing key, recent (last 5 yr) international research findings with regard to both the prevalence and effects of food and beverage advertising on children's intake. Evidence relating to the two main avenues of food marketing exposure, television, and the Internet, is explored and consideration is given to the differences in consumer experience of these types of promotion. Despite methodological differences and the varying population samples studied, the outcomes are broadly consistent – food advertising is prevalent, it promotes largely energy dense, nutrient poor foods, and even short‐term exposure results in children increasing their food consumption. Policymakers are implored to drive forward meaningful changes in the food environment to support healthier choices and reduce the incidence of obesity and related diseases. This article aims at providing an overview of recent developments in this field. After limiting the search to the last five full years 2009–2014, we searched the following databases: Web of Knowledge and PubMed (keyword search terms used: television, Internet, new media, food advertising, food marketing, children, food intake, energy intake, consumption, and combinations of these terms). In addition we used the references from the articles obtained by this method to check for additional relevant material.     

Nutritional and energetic consequences of sweetened drink consumption in 6- to 13-year-old children

OBJECTIVE: To study the effects of excessive sweetened drink consumption on daily energy balance and nutrient intake in a longitudinal study of children. SUBJECTS AND METHODS: Daily dietary intakes of 30 children aged 6 to 13 years old were collected over 4 to 8 weeks. Weights and heights of children were measured at the beginning and end of the study in 21 children. Data were analyzed by analysis of variance (ANOVA) (PROC MIXED in SAS) and multiple regression. RESULTS: Excessive sweetened drink consumption (>12 oz/day) displaced milk from children's diets (122-147 g/day less milk drank, P <.0001) because caregivers served less milk and the children consumed smaller amounts of milk. The consequences were lower daily protein, calcium, magnesium, phosphorus, and vitamin A intakes. Because children failed to reduce consumption of solid foods to compensate for the caloric contribution of sweetened drinks, higher daily energy intakes were observed. Consequently, the greater the sweetened drink consumption the greater the weight gain (1.12 +/- 0.7 kg) compared with children who consumed <12 oz per day (0.32-0.48 +/- 0.4 kg). CONCLUSIONS: Excessive sweetened drink consumption is associated with the displacement of milk from children's diets, higher daily energy intake, and greater weight gain.     

Ethnic issues in the epidemiology of childhood obesity

Childhood obesity may be seen as a marker for high-risk dietary and physical inactivity practices. Recent increases in the prevalence of overweight and obesity among American children are not limited to one age, gender, or ethnic group, which suggests that unique behaviors of the members of various racial or ethnic subgroups of the population are unlikely to be the major contributing factors. Rather, it seems that environmental changes promoting increased energy intake and decreased energy output are occurring and have widespread impact on children from various backgrounds. Although no ethnic group is immune from the current shift in energy balance, differential rates of overweight seem to exist among ethnic groups. National probability samples of African-American, Hispanic, and white children in the United States provide clear evidence that white children are at lower risk for childhood overweight than are African-American or Hispanic children. Of concern is the lack of national data on the prevalence of overweight and obesity for Native-American and Asian-American groups. Also of concern is the aggregation of racial and ethnic subgroups, which may render prevalence rates meaningless. This possibility is clearly true with some surveys of weight status that combine diverse populations, such as Asians and Pacific Islanders, into one group. The high rates of obesity in African-American, Hispanic, and Native-American children are of concern. Although parental SES is associated inversely with childhood obesity among whites, higher SES does not seem to protect African-American and Hispanic children against obesity. In these groups, childhood obesity does not seem to be associated significantly with parental income and education. Health consequences of childhood obesity include a higher prevalence of type 2 diabetes and an increased risk for adverse levels of lipids, lipoproteins, and blood pressure. The effects of recently reported unprecedented levels of childhood overweight on subsequent risk for obesity in middle age are not known until future longitudinal data can be collected. It seems likely, however, that future health consequences of current early and severe childhood obesity will be staggering. Funding for adult follow-up of longitudinal studies of high-risk African American, Hispanic, and Native-American children is needed urgently to provide information on the long-term effects of childhood obesity. Halting the obesity epidemic is a formidable task, but the success in recent decades of drastically reducing childhood undernutrition offers hope and should spur similar action and leadership efforts. Promotion of efforts to reduce excess caloric intake with efforts to increase energy expenditure should receive paramount attention in the design of health programs. Given the relatively few published obesity-prevention and treatment studies that are designed to address specific cultural issues, it is important to promote the development of culturally appropriate intervention strategies that are shown to be effective among youth of diverse backgrounds. Although the dietary and activity goals will be similar, parental, family, and community messages and techniques grounded in cultural traditions and norms will be different for each ethnic group. This approach is crucial in the United States, a country with an increasingly diverse population.     

Television and children's consumption patterns. A review of the literature

The recent increase in childhood obesity has, among other things, focused attention on the role that television may play. This paper summarizes results of studies published in peer review journals since 1970 with data pertaining to the relationship between television use and children's food intake. Studies fall into four categories: content analyses; effects of television advertising on children's food behaviors; television and pediatric obesity, with effects on children's dietary intake and physical activity; and television use and children's food consumption patterns. Content analyses have shown that food is the most frequently advertised product category on children's TV. The majority of these ads target highly sweetened products, but more recently, the proportion from fast food meal promotions has been growing. Controlled studies on children's choices have consistently shown that children exposed to advertising choose advertised food products at significantly higher rates than do those not exposed. Purchase request studies have documented associations between number of hours of TV watched and number of requests from the child to the mother for specific food items, as well as the presence of those items in the home. Greater TV use has been associated with higher intakes of energy, fat, sweet and salty snacks, and carbonated beverages and lower intakes of fruit and vegetables. Several large studies have documented associations between number of hours of TV watched and both the prevalence and incidence of obesity. The combination of lifestyle factors that accompany heavy television use appear to place children at risk of obesity and poor nutritional status.     

Access to food outlets and children's nutritional intake in urban China: a difference-in-difference analysis

ABSTRACT: BACKGROUND: In recent years supermarkets and fast food restaurants have been replacing those "wet markets" of independent vendors as the major food sources in urban China. Yet how these food outlets relate to children's nutritional intake remains largely unexplored. METHOD: Using a longitudinal survey of households and communities in China, this study examines the effect of the urban built food environment (density of wet markets, density of supermarkets, and density of fast food restaurants) on children's nutritional intake (daily caloric intake, daily carbohydrate intake, daily protein intake, and daily fat intake). Children aged 6-18 (n = 185) living in cities were followed from 2004 to 2006, and difference-in-difference models are used to address the potential issue of omitted variable bias. RESULTS: Results suggest that the density of wet markets, rather than that of supermarkets, positively predicts children's four dimensions of nutritional intake. In the caloric intake model and the fat intake model, the positive effect of neighborhood wet market density on children's nutritional intake is stronger with children from households of lower income. CONCLUSION: With their cheaper prices and/or fresher food supply, wet markets are likely to contribute a substantial amount of nutritional intake for children living nearby, especially those in households with lower socioeconomic status. For health officials and urban planners, this study signals a sign of warning as wet markets are disappearing from urban China's food environment.     

Leptin: obesity, diabetes and other peripheral effects--a review

Abstract: There is an increasing epidemic of obesity in the Western and developing world that has not spared children and, hence, is of great concern. Obesity presents numerous physiological and psychosocial problems for the child. Childhood obesity not only increases the risk of obesity in adulthood, it is associated with type 2 diabetes mellitus; is the leading cause of pediatric hypertension; increases the risk of coronary heart disease; and increases stress on the weight-bearing joints. Social and psychological problems are also significant consequences of obesity in children, with lowering of self-esteem and its effects on relationships with peers. Obesity is clearly associated with increased levels of the recently discovered hormone, leptin. Leptin, secreted from adipocytes, is involved in the regulation of food intake, energy expenditure, and energy balance in humans. This review focuses on the hormone, leptin, in an effort to document some of its many local and systemic effects on the body and, specifically, its potential role in obesity-induced diabetes.