Preventing Childhood Obesity E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Evidence-Based Medicine
• Sprache: Englisch

Seitenzahl: 907

Veröffentlichungsjahr: 2011

Beschreibung

Obesity is one of the biggest public health challenges in the 21st century. Devising effective policy and practice to combat childhood obesity is a high priority for many governments and health professionals internationally. This book brings together contributors from around the world and showcases the latest evidence-based research on community and policy interventions to prevent unhealthy weight gain and improve the health and well-being of children. The authors highlight from the evidence available what is and what is not effective and provide recommendations on how to implement and evaluate promising interventions for obesity prevention.

This book is an essential read for all public health practitioners, early childhood professionals, health care providers and clinicians working to reduce the prevalence of childhood obesity in their communities.

Leseprobe

Contents

Contributors

Foreword

Preface

Part 1: The context

1 The childhood obesity epidemic

Summary

Introduction

Measuring the prevalence of obesity

Prevalence levels

Trends over time

Demographics of child adiposity

Child obesity and tracking to a dulthood

Co-morbidities of child obesity

Treatment implications

References

2 Lessons from the control of other epidemics

Summary

Introduction

Shifting from an individual to public health approach

Shifting from an international to a global public health approach

Optimize effectiveness (in terms of quality and coverage) of existing efficacious interventions especially in health sector

Decentralized care focused at the primary health care level

More sophisticated advocacy responses

Developing appropriate monitoring systems

Developing an evidence base for action and focusing on key research questions

References

3 Childhood obesity prevention overview

Summary

Introduction

A life-course approach to obesity prevention

Linking community, national and global approaches

Food marketing to children

References

4 No country for fat children? Ethical questions concerning community-based programs to prevent obesity

Summary

Introduction

The bad effects of moral panics

Responsibility and the complex causal network

Children’s right to protection from unhealthy commercial influences

Evidence

Stigmatization

Parental involvement

Durable skills, habits, virtues

Proportionality

Slippery slope

Conclusion

References

5 A human rights approach to childhood obesity prevention

Summary

Introduction

Human rights declarations applicable to childhood obesity

Approaches to incorporating human rights into childhood obesity prevention

Conclusions

References

Part 2: Evidence synthesis

6 Evidence framework for childhood obesity prevention

Summary and recommendations for practice

Introduction

Definitions and hierarchies of evidence

Evidence on the burden and determinants of obesity

Opportunities for action—who, where, how?

Effectiveness of potential interventions

Creating a portfolio of interventions

Evidence needs

Conclusions

Acknowledgements

References

7 Evidence of multi-setting approaches for obesity prevention: translation to best practice

Summary and recommendations for practice

Method

Social change models: what can we learn?

Community approaches to obesity prevention

Community-based obesity prevention interventions in children

The benefits of this approach to obesity prevention

Best practice recommendations for intervention activities

Summary

References

8 Evidence of the influence of home and family environment

Summary and recommendations for practice

Introduction

The physical environment

Discussion and conclusions

References

9 Obesity prevention in early childhood

Summary and recommendations for practice

Introduction

Method

Interventions during pregnancy

Interventions to promote breastfeeding

Home/family-based interventions

Interventions in child-care settings

Conclusion and implication

References

10 Obesity prevention in primary school settings: evidence from intervention studies

Summary and recommendations for practice

Method

Rationale/importance of primary setting

Defining the primary school settings

Type of Interventions

What has been proven ffective

Future perspectives

References

11 Obesity prevention in secondary schools

Summary and recommendations for practice

Method

Adolescence and overweight and obesity

School, family and community approaches

Evidence for obesity prevention in adolescence

References

12 The prevention of childhood obesity in primary care settings: evidence and practice

Summary and recommendations for practice

Introduction

Is childhood overweight and obesity seen as an important issue for primary care?

Evidence and guidelines for obesity prevention interventions in primary care

The role of parents

Conclusions

References

13 Links between children’s independent mobility, active transport, physical activity and obesity

Summary and recommendations for practice

Introduction

Battery-reared children: the extent of the problem

The confinement of children: possible causes

Promising policies and practices

Conclusion

Acknowledgement

References

14 Evidence on the food environment and obesity

Summary and recommendations for practice

Introduction

Changes in the food environment—the nutrition transition

Promising interventions—regulating the food environment

Conclusion

References

15 Food and beverage marketing to children

Summary and recommendations for practice

Introduction

The nature of marketing

The power of marketing: the food business

Tobacco control: ten marketing lessons

Translation into practice

Conclusion

References

16 Poverty, household food insecurity and obesity in children

Summary

Introduction

The relationship between poverty and food insecurity and the prevalence of obesity in children

Public policy and practice to address obesity in financially stressed or food insecure families

References

17 Socio-cultural issues and body image

Summary

Introduction

The socio-cultural environment

The socio-cultural environment in context

Translation into practice

Conclusions/summary

References

18 Developing countries perspective on interventions to prevent overweight and obesity in children

Summary and recommendations for research

Introduction

Setting the context for interventions

Childhood obesity prevention interventions in the developing world

References

Part 3: Evidence generation and utilization

19 Evaluation of community-based obesity interventions

Summary and recommendations for research

Introduction

Evaluation: purpose and resources

Complexity: moving beyond “what works?”

Evaluating complex interventions—research stages and research questions

Formative evaluation

Summative evaluation

Evaluation funding

Conclusion

Acknowledgements

References

20 Economic evaluation of obesity interventions

Summary and recommendations for research

Introduction

Why involve economics?

Describing and projecting the cost burden of obesity

Evaluating interventions to prevent obesity

The challenges in producing quality economic evaluations

Moving beyond economic evaluation of single interventions to priority setting

Conclusions

References

21 Monitoring of childhood obesity

Summary and recommendations for research and practice

Definitions

Purposes of monitoring

Monitoring of (potential) determinants and consequences of obesity

Conclusions

References

22 Knowledge translation and exchange for obesity prevention

Summary and recommendations for research and practice

Introduction

The characteristics of KTE needed to support obesity prevention

Frameworks to support KTE

Options for KTE for obesity prevention

Facilitators of KTE for obesity prevention

Knowledge translation in action: translation into practice

Conclusion

References

23 The role of advocacy

Summary

Introduction

What is public health advocacy?

Why do we need advocacy?

Elements of effective advocacy

Planning for advocacy

Conclusion

References

Part 4: Policy and practice

24 The role of policy in preventing childhood obesity

Summary

Introduction

Why is policy important for preventing childhood obesity?

The food system as a framework for analysing food policy

The policy environment for physical activity

Policy instruments

How evidence gets incorporated into policy-making

Case studies of how evidence is (or is not) incorporated into policy

Creating the policy backbone for obesity prevention

Conclusion

References

25 Developing the political climate for action

Summary and recommendations for practice

Introduction

The contrasts in the responses to food safety and diet-related disease issues

Background to the obesity crisis: the reasons for its early neglect

Putting obesity and chronic disease on WHO’s agenda

Establishing a policy focus on obesity per se

Achieving synergy among non-governmental organizations

The next steps

Conclusion

References

26 Community interventions—planning for sustainability

Summary and recommendations for research and practice

Introduction

Selection of communities

Principles of community engagement and capacity building

Principles of program design and planning

Principles of implementation and sustainability

Principles of evaluation

Key challenges in establishing and sustaining community interventions

Case study 1 the EPODE program, France

Case study 2 Sentinel site for obesity prevention, Victoria, Australia

References

27 Community capacity building

Summary and recommendations for research and practice

Introduction

What is community capacity building?

A critic’s perspective

Why build community capacity?

The application of community capacity building to childhood obesity prevention

Raising community awareness of health risks

Strategies to foster community identity and cohesion

Education to increase health literacy

Facilitating access to additional resources

Developing structures for community decision making

Social and political support

Incorporating the evidence

Conclusions

References

28 Social marketing to prevent childhood obesity

Summary and recommendations for research and practice

Introduction

Marketing principles

Incorporating the evidence

Conclusion

References

29 Obesity in early childhood and working in pre-school settings

Summary and recommendations for research and practice

Introduction

Growth and excess weight assessment in early childhood

Developmental origins of obesity

Energy intakes and feeding patterns in young children

Physical activity and inactivity in young children

Environments and early childhood settings

Conclusions

References

30 Working with schools

Summary and recommendations for research and practice

Introduction

Dealing with healthy eating and physical activity in schools

Context of health promoting schools

Selection of good practice

Conclusions

References

31 Working in primary care

Summary and recommendations for research and practice

Introduction

Antenatal and infancy

Childhood

Adolescence

Incorporating the evidence

References

32 Working with minority groups in developed countries

Summary and recommendations for research and practice

Introduction

Who should represent the community?

How can community involvement be supported?

What messages and strategies to use?

Responding to community needs

Conclusion

References

33 Developing country perspectives on obesity prevention policies and practices

Summary and recommendations for research and practice

Introduction

Access to food, poverty and childhood obesity

Rising food prices and poverty

Including obesity prevention considerations in nutrition programs in developing and transitional societies

Conclusions

References

34 Preventing childhood obesity: looking forward Index

Introduction

Recognition of the health effects

The role of policy and environmental change

Perception of a common threat

A common frame

Grass-roots mobilization

Conclusion

References

Index

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Library of Congress Cataloging-in-Publication Data

Preventing childhood obesity: evidence, policy, and practice / edited byElizabeth Waters... [et al.].p.; cm.Includes bibliographical references.ISBN 978-1-4051-5889-31. Obesity in children–Prevention. I. Waters, Elizabeth, 1966–[DNLM: 1. Obesity–prevention & control. 2. Child Health Services. 3. Child NutritionalPhysiology Phenomena. 4. Child. 5. Evidence-Based Medicine–methods. WD 210 P435 2010]RJ399.C6P74 2010618.92′398–dc222009038756

Preface

If we had all the evidence, practice experience and policy insight, what would be the best investments to improve the health and well-being of children, reduce the likelihood and impact of increased weight gain, improve health outcomes and minimize the potential increased morbidity associated with being less advantaged?

In September 2006, the first international meeting on Community-based Interventions for Child Obesity Prevention was held in Geelong, Australia, to accompany the 10th International Congress on Obesity. This was an outstanding event that attracted a remarkable collection of those working in this area internationally. It was accompanied by site visits to two major community-based interventions in Victoria: Fun’n’ Healthy in Moreland!—a five-year school community intervention in an inner urban metropolitan area of Melbourne, and Be Active Eat Well, in the rural town of Colac, which provided attendees with opportunities to engage with community partners involved with innovating and implementing programs designed to increase healthy eating sustainably, increase physical activity and enjoyment, address social determinants such as parental employment and social participation, and address neighborhood renewal and local government policies.

The two-day meeting that followed was the first time that evidence, policy, practice and passion provided the foundation for discussions between researchers, policy-makers, practitioners and community. What was eminently clear was the vast array of issues that impact on decisions and programs required to address the seemingly unstemmable tide of childhood obesity and the commonality of challenges that the international community faces.

However, while childhood obesity presents us with a particular set of risks for children and the population as a whole, we are still working with children, adolescents, families and communities on an issue that is core to health and well-being—healthy eating, physical activity, and feeling happy and connected. There is a vast history of successful and unsuccessful initiatives to improve population health outcomes, and understanding what has worked for whom and why is pivotal to solutions. If this particular health issue is conceptualized in isolation from other issues for children, families, communities, politics and policy, then it is unlikely that we will see improvements in health and well-being for children and reductions in health concerns associated with obesity. We clearly need to be working together to find efficient ways of understanding the evidence base, using comparable high quality methods for understanding what is, and is not, working, and developing effective solution-oriented partnerships between researchers, policy-makers and practitioners.

It is easy to be overwhelmed by the complexity of the factors that have contributed to the problem, the scale at which changes may need to occur, and the sectors that need to be talking together. This book aims to help. The full range of chapters has been brought together to highlight cutting-edge research, and to provide a review of current practice. The closely connected interface between the research and policy agenda has catalysed new ideas and perspectives based on research findings. The book is written by leading researchers in the field internationally. It has been designed to be relevant to both developing and developed countries, those with resources and those with less, those with strong effective policy frameworks and those without.

The book is separated into four sections: the context, evidence synthesis, evidence generation and policy and practice. We aimed to have those writing about the evidence base making recommendations for policy and practice, and vice versa. The content area is one in which a vast amount of research is currently underway, and one that is challenging governments and industry, in terms of solutions.

Contributors

Mulugeta Abebe BSocSc

Health Promotion OfficerMerri Community Health ServicesVictoria, Australia

Rebecca Armstrong MPH, BN, BAppSci (Health Promotion) (Hon)

Senior Research FellowCochrane Public Health Review GroupJack Brockhoff Child Health and Wellbeing Program,McCaughey CentreMelbourne School of Population HealthUniversity of MelbourneVictoria, Australia

Louise A. Baur PhD, FRACP

Professor, Discipline of Paediatrics and Child HealthUniversity of Sydney; Director, Weight ManagementServicesThe Children’s Hospital at WestmeadSydney, Australia

A. Colin Bell PhD

Co-joint Associate ProfessorUniversity of NewcastleWallsend, Australia

Jean-Michel Borys MD

EPODE’s Director, Paris, FranceNutritionist, Centre KennedyArmentieres, France

Sue Bowker MSc

Head of Branch, Young and Older PeopleHealth Improvement DivisionWelsh Assembly GovernmentCardiff, UK

Joh3246annes Brug PhD

Director, EMGO Institute for Health and Care ResearchChair of Division VI; Head, Department of Epidemiologyand BiostatisticsVU University Medical Center AmsterdamThe Netherlands

Goof J. Buijs MSc

Manager Schools for Health in Europe Network(SHE Network)Netherlands Institute for Health Promotion NIGZWoerden, The Netherlands

Matthew Burke PhD

Research Fellow, Urban Research ProgramGriffith University, BrisbaneAustralia

Cate Burns PhD

Deakin University, WHO Collaborating Centre for ObesityPreventionFaculty of Health, Medicine, Nursing and BehaviouralSciencesMelbourne, Australia

Georgina Cairns BSc, MBA

Research Fellow, Institute for Social MarketingUniversity of Stirling and the Open UniversityStirling, UK

Rishi Caleyachetty MBBS, MSc

Doctoral StudentMRC Epidemiology UnitAddenbrooke’s HospitalCambridgeUK

Rob Carter PhD

Head, Health Economics UnitDeakin UniversityVictoriaAustralia

Mickey Chopra MD, PhD

Health Systems Research UnitMedical Research CouncilWestern Cape, South AfricaExtraordinary ProfessorSchool of Public HealthUniversity of the Western CapeParowSouth Africa

Deborah A. Cohen MD, MPH

Senior Natural ScientistThe RAND CorporationSanta MonicaParowCA, USA

Camila Corvalán MPH, MD, PhD

Professor, School of Public HealthFaculty of MedicineUniversity of ChileSantiago, Chile

Carey Curtis PhD, DipTP, CertTHE, MRPTI, MPIA

Australasian Centre for the Governance andManagement of Urban Transport andProfessor, WA Planning and Transport Research CentreCurtin University of TechnologySchool of Built EnvironmentBentley, Australia

Inez de Beaufort PhD

Professor of Healthcare EthicsErasmus Medical CenterRotterdam, The Netherlands

Ilse De Bourdeaudhuij PhD

Full Professor, Department of Movement and SportSciencesGhent UniversityGent, Belgium

Andrea de Silva-Sanigorski, MHN, PhD

Senior Research Fellow, WHO Collaborating Centre forObesity PreventionDeakin University & Melbourne School of PopulationHealthUniversity of MelbourneVictoria, Australia

William H. Dietz MD, PhD

Director, Division of Nutrition, Physical Activity, andObesityNational Center for Chronic Disease Prevention andHealth PromotionCenters for Disease Control and PreventionAtlanta, USA

Colleen Doak MA, PhD

Assistant Professor, Faculty of Earth and Life SciencesDepartment of Health SciencesVU UniversityAmsterdam, The Netherlands

Maureen Dobbins RN, PhD

Associate Professor, McMaster University School ofNursingand Department of Clinical Epidemiology andBiostatisticsFaculty of Health Sciences and Career ScientistOntario Ministry of Health and Long-Term CareHamilton, ON, Canada

Mitch J. Duncan PhD

Senior Post-Doctoral Research FellowInstitute for Health and Social Science ResearchCQUniversity AustraliaRockhampton, Australia

Christina Economos PhD

New Balance Chair in Childhood NutritionDorothy R. Friedman School of Nutrition Science andPolicyTufts UniversityAssociate Director, John Hancock Center for PhysicalActivity and NutritionBoston, USA

C. Raina Elley BA(Hons), MBCHB, FRNZCGP, PhD

Senior Lecturer, Department of General Practice andPrimary Health CareSchool of Population HealthUniversity of AucklandAuckland, New Zealand

Eva Elliott PhD

RCUK Academic Fellow, Cardiff Institute of Society andHealthSchool of Social SciencesCardiff UniversityCardiff, UK

Edward A. Frongillo Jr. PhD

Professor and Chair, Department of Health Promotion,Education, and BehaviorUniversity of South CarolinaColumbia, SC, USA

Lisa Gibbs PhD

Senior Research Fellow, Community Partnerships &Health Equity ResearchJack Brockhoff Child Health and Wellbeing Program,McCaughey CentreMelbourne School of Population HealthUniversity of MelbourneVictoria, Australia

Gerard Hastings PhD, OBE

Director, Institute for Social MarketingStirling and the Open UniversityUK

Nadine Henley PhD

Professor of Social MarketingDirector of the Centre for Applied Social MarketingResearchFaculty of Business and LawEdith Cowan UniversityJoondalup, Australia

Rebecca Hillier MBBS, BA (Hons)

Honorary Research Fellow & G.P. RegistrarDepartment Public Health PolicyLondon School of Hygiene & Tropical MedicineLondon, UK

Karen Hoare MSc, AdvDip Health Sciences, NP, RN, FCNA (NZ), RGN, RSCN, RHV (UK)

Lecturer, Goodfellow Unit and School of NursingUniversity of AucklandAuckland, New Zealand

Søren Holm BA, MA, MD, PhD, DrMedSci

Professor of BioethicsCentre for Social Ethics and PolicySchool of LawUniversity of ManchesterManchester, UK

Laura M. Irizarry MS

Center for Research in Nutrition and HealthNational Institute of Public HealthCuernavacaMorelos, Mexico

Rachel Jackson-Leach MSc Nutrition

Senior Policy OfficerInternational Association for the Study of Obesity(IASO)London, UK

W. Philip T. James MD, FRCP

President, International Association for the Study ofObesityLondon School of Hygiene and Tropical MedicineLondon, UK

Sonya Jones PhD

Center for Research in Nutrition and Health DisparitiesUniversity of South CarolinaColumbia, SC, USA

Juliana Kain MPH

Institute of Nutrition and Food Technology (INTA)University of ChileSantiago, Chile

Stef Kremers PhD, MPH

Department of Health PromotionNUTRIM School for Nutrition, Toxicology and MetabolismMaastricht University Medical CentreMaastrichtThe Netherlands

Shiriki Kumanyika PhD, MPH

Professor of EpidemiologyDepartment of Biostatistics and Epidemiologyand Department of Pediatrics (Gastroenterology;Nutrition Section)University of Pennsylvania School of MedicinePhiladelphia, PA, USA

Mark Lawrence BSc (Hons), Grad Dip Nutr and Diet, Grad Dip Epidem and Biostats, MSc, PhD

Director Food Policy UnitWHO Collaborating Centre for Obesity PreventionDeakin UniversityMelbourne, Australia

Tim Lobstein PhD

Director of Policy and ProgrammesInternational Association for the Study of ObesityLondon, UKResearch Fellow, SPRU—Science and Technology PolicyResearchUniversity of SussexBrighton, UK

Karen Lock BMBCh, PhD

Clinical Senior Lecturer in Public HealthLondon School of Hygiene and Tropical MedicineLondon, UK

Jane Martin BA (Hons), MPH

Senior Policy AdviserObesity Policy CoalitionCarlton, Australia

Helen Mavoa PhD (Anthropology)

WHO Collaborating Centre for Obesity PreventionMelbourne, Australia[formerly School of Psychology, Deakin University]

Marj Moodie DrPH

Senior Research Fellow, Deakin Health EconomicsDeakin UniversityMelbourne, Australia

Laurence Moore PhD, FFPH, FRSS

Director, Cardiff Institute of Society and HealthSchool of Social SciencesCardiff UniversityCardiff, UK

Luis A Moreno MD, PhD

Professor E.U. Ciencias de la SaludUniversidad de ZaragozaZaragoza, Spain

Ladda Mo-suwan MD

Associate Professor, Department of PediatricsPrince of Songkla UniversityHat Yai, SongkhlaThailand

Simon Murphy PhD, CPsychol

Senior Research FellowCardiff Institute of Society and HealthSchool of Social SciencesCardiff UniversityCardiff, UK

Naomi Priest PhD

Jack Brockhoff Child Health and Wellbeing Program,McCaughey CentreMelbourne School of Population HealthUniversity of MelbourneVictoria, Australia

Lauren Prosser BAppSci, PhD

Research Fellow, The McCaughey CentreVicHealth Centre for the Promotion of Mental Health andCommunity WellbeingMelbourne School of Population HealthUniversity of MelbourneVictoria, Australia

Sandrine Raffin MMAA

Co-founder of EPODEParis, France

André M.N. Renzaho PhD, MPH, MPHAA

Senior Research Fellow, WHO Collaborating Centre forObesity PreventionPublic Health Research Evaluation and Policy ClusterFaculty of Health, Medicine, Nursing and BehaviouralSciencesDeakin UniversityBurwood, Australia

Neville Rigby

European Policy Adviser to the Obesity ForumNeville Rigby & AssociatesLondon, UK

Elisha Riggs BAppSc(Health Promotion) (Hons)

Research Fellow, The McCaughey CentreMelbourne School of Population HealthFaculty of Medicine, Dentistry and Health SciencesUniversity of MelbourneCarlton, Australia

Juan A. Rivera PhD

Center for Research in Nutrition and HealthNational Institute of Public HealthCuernavaca, Morelos, Mexico

Vivian Romero PhD

MURP Research Associate, GAMUTUniversity of MelbourneWindsor, Australia

Andrea M. Sanigorski MHN, PhD

Senior Research Fellow, WHO Collaborating Centre forObesity PreventionDeakin University & Melbourne School of PopulationHealthUniversity of MelbourneVictoria, Australia

Anne Simmons MND

Research Fellow, Deakin University School of Exercise andNutrition SciencesGeelong, Australia

Saskia te Velde PhD

Post-doctoral ResearcherDepartment for Epidemiology & BiostatisticsEMGO Institute for Health and Care Research andVU University Medical CenterAmsterdam, The Netherlands

Marieke ten Have MA

Researcher at the Department of Medical Ethics andDepartment of Public Health at the Erasmus UniversityRotterdamRotterdam, The Netherlands

Paul Tranter PhD

Associate Professor in GeographySchool of Physical, Environmental and MathematicalSciencesUniversity of New South WalesAustralian Defence Force AcademyCanberra, Australia

Tommy L.S. Visscher PhD

Research Coordinator, Research Centre for OverweightPreventionEMGO Institute for Health and CareVU UniversityAmsterdam, The Netherlands

Carolyn Whitzman PhD

Certified Practicing PlannerPlanning Institute of AustraliaSenior Lecturer in Urban PlanningFaculty of Architecture, Building and PlanningUniversity of MelbourneParkville, Australia

Yang Gao PhD, MPH, Bmed

Instructor, School of Public Health and Primary CareThe Chinese University of Hong KongHong Kong, SAR China

Foreword

Obesity became a major health threat for higher income countries in the last decades of the 20th Century and now early in the 21st Century, most of the world must consider this challenge to our ongoing quest for better health and longer healthy life for all our citizens. A particular concern, both for the long term impact of its sequelae and because it may be more amenable to prevention, is childhood obesity. Preventing childhood obesity must be one of the top priorities of public health and clinical medicine and indeed, public policy.

Preventing Childhood Obesity, with multiple chapters by global experts from diverse fields, offers a breadth of material and thought on this health challenge that can serve as a thorough introduction for those new to the field and a useful text for those already engaged in it. While, many books, monographs and papers have been written with a particular national focus, this book offers a truly global perspective. After setting the nature and extent of the problem (“The context”), it then examines the evidence for prevention in multiple settings and how that evidence can be applied to interventions, policies and practice. Included in the discussions on childhood obesity are important perspectives on: economics, programme evaluation, monitoring, advocacy, social determinants, politics and stigmatization.

Countries well beyond Europe, North America, Australia and New Zealand are now recognizing childhood obesity as national health threats, for example Brazil, Chile, South Africa, India and China. Preventing Childhood Obesity offers us all a concise clear examination of the elements, challenge, setting and complexity of obesity prevention and control while providing the basis for taking steps to address the challenges. It has taken several decades for our environment and lifestyle to include multiple elements that promote excess caloric intake and diminished caloric expenditure. It will likely take decades for us to reverse such trends but we all need to make this effort.

Jeffrey P. Koplan, MD, MPHDirector, Emory Global Health InstituteEmory UniversityAtlanta, Georgia, USAFebruary 2010

PART 1

The context

This section of five chapters paints the big picture for childhood obesity prevention. The problem needs to be well articulated before the solutions, which are the focus for most of the book, can be defined. The rise in obesity has many societal and environmental drivers so the options for solutions to reduce childhood obesity must be multi-dimensional and sustained. The solutions are at once simple, from a behavioral action point of view (eating less and moving more), and highly complex, from a societal, economic and cultural point of view. The solutions must also give primacy to what should be a prevailing societal responsibility to provide safe and healthy environments for children. The human rights approach to childhood obesity, therefore, provides an important frame of reference for solutions to be developed and communicated.

The epidemiology of the childhood obesity epidemic gives us many clues about its determinants and Chapter 1, led by Tim Lobstein from the International Obesity Taskforce, plots the global trends in prevalence rates. The rise has been rapid but varied, and much of the variation in prevalence is likely to be explained by environmental and socio-cultural factors——a neglected area of obesity research. The increasing demands on pediatric health services and the tracking of obesity into adulthood, and thus the future demand on adult health services, are two enormous challenges we face. We need to look widely for the answers to the obesity epidemic and there are many valuable lessons to be learned from the successful control of other epidemics. This important evidence, which is explored in Chapter 2 by Mickey Chopra, is known to many epidemiologists and public health researchers who work across different health issues, but the lessons need to be applied systematically to obesity. The central role of policy is one crucial lesson that has yet to be well applied in obesity prevention.

Terms “life-course”, “multi-sector”, multi-strategy”, “whole-of-society” are often used to describe the approaches to obesity prevention and these are discussed in Chapter 3 by Ricardo Uauy and colleagues. What becomes an inescapable conclusion is that we cannot hope to reduce childhood obesity in the face of the continuing barrage of commercial marketing of “junk” food to children. Something must be done to reduce this overwhelming driver of obesogenic environments as a central plank of childhood obesity prevention. Taking an ethics-based, child rights approach is vital to give gravity to society’s response. It also ensures that the ethical dilemmas intrinsic to obesity prevention, such as the potential for risk and the balance between paternalism and individualism, are assessed and managed in the best interests of child health. Chapter 4, led by Marieke ten Have, and Chapter 5, led by Naomi Priest, enter this important territory and, again, food marketing to children arises as a fundamental problem.

CHAPTER 1

The childhood obesity epidemic

Tim Lobstein,1,2Louise A Baur3 and Rachel Jackson-Leach1

1International Association for the Study of Obesity, London, UK

2SPRU—Science and Technology Policy Research, University of Sussex, Brighton, UK

3Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia

Summary

Childhood obesity can be measured in various ways, but applying a single method across all available data shows a rapid rise in the numbers of children affected.Very few countries have shown a reversal of this trend, but prevalence levels vary across populations, and according to social demographics.The rise in child obesity will almost certainly lead to a rise in adult obesity rates.Child obesity is a health concern itself and will increase the demand for pediatric treatment.

Introduction

In many developed economies child obesity levels have doubled in the last two decades.1 The impending disease burden in these countries has been described by medical professionals as “a public health disaster waiting to happen”,2 “a massive tsunami”,3 and “a health time-bomb”.4 In emerging and in less developed economies, child obesity prevalence levels are also rising,5 especially among populations in urban areas where there may be less necessity for physical activity, greater opportunities for sedentary behavior and greater access to energy-dense foods and beverages.

This chapter looks at the figures and predictions, and considers the implications in terms of children’s obesity-related health problems and the need for policy development for both pediatric treatment services and public health preventive action.

Measuring the prevalence of obesity

Policy-makers will need to evaluate the trends in child obesity and the success of any interventions, but they face an initial problem in agreeing a clear definition of what constitutes excess body weight in a child. Among adults, obesity is generally defined as a BMI greater than 30 kg/m2, and overweight as a BMI between 25 and 30 kg/m2, but for children there are difficulties in defining a single standard as normally-growing children show significant fluctuations in the relationship between weight and height. Charts showing weight, height and BMI for children by age and gender are commonly used, but with different cut-off points for overweight and obesity, such as 110% or 120% of ideal weight for height, or weight-for-height greater than 1 or 2 standard deviations above a predefined mean, or a BMI-for-age at the 85th, 90th, 95th or 97th percentiles, based on various reference populations.1

For young children, it has been common practice to use “weight-for-height” rather than BMI. This stems from existing definitions used in the assessment of underweight and stunting, where “weight-for-age”, “height-for-age” and “weight-for-height” are used to assess infant growth. The measures are still occasionally used for assessing overweight in young children, usually by taking a value of two standard deviations (Z >+2.0) above a reference population mean as the criteria for excess weight for a given age and gender.

In recent years, BMI has been increasingly accepted as a valid indirect measure of adiposity in older children and adolescents for survey purposes,1,6 leading to various approaches to selecting appropriate BMI cut-off values to take account of age and gender differences during normal growth.7–12 A number of different BMI-for-age reference charts have been developed, such as those from the US National Centre for Health Statistics,9 the United Kingdom10 and France.11

An expert panel convened by the International Obesity TaskForce (IOTF) proposed a set of BMI cut-offs based on pooled data collected from Brazil, Britain, Hong Kong, Singapore, the Netherlands and the USA. The IOTF definitions of overweight and obesity are based on BMI centile curves that passed through the adult cut-off points of BMI 25 and 30. The resulting set of age- and gender-specific BMI cut-off points for children was published in 2000.12

The World Health Organization (WHO) has for many years recommended using a set of cut-offs based on a reference population derived from the USA, but more recently the WHO has been reviewing their recommendations. There had been concern that the USA data included large numbers of formula-fed infants with growth patterns that differed from breast-fed infants, and which underestimated the true extent of overweight in younger children. WHO has now published a new “standard” set of growth charts for children aged 0–5 years, based on data from healthy breast-fed babies.13 It is unclear at this stage what BMI cut-off values should be used from this healthy population to define overweight and obesity, with both centile and Z-score options available in published tables. Further reference charts are available for children aged 5–19 years, based on a revision of US data collected in 1977 adapted to match the standards for 0–5-year-olds.

Care should be taken when looking at published prevalence figures for overweight and obesity. Some authors use “overweight” to define all members of a population above a specified cut-off, while others mean “overweight” to mean those above one cut-off but not above a higher cut-off that defines obesity. Thus, in some reports the prevalence value for “over-weight” children includes obese children and in other reports it does not. In this section “overweight” includes obese, so the term should properly be understood to mean “overweight including obese”. Readers should also note that prevalence levels using reference curves from the USA sometimes refer to “at risk of overweight” and “overweight” for the top two tiers of adiposity, and sometimes to “overweight” and “obese”.

It should also be noted that the definitions are very helpful for making comparisons between different population groups, or monitoring a population over time. However, for the clinical assessment of children, serial plotting of BMI on nationally recommended BMI-for-age charts should be coupled with more careful examination of the child in order to be sure that, for example, a high BMI is not due to extra muscle mass or to stunted linear growth.

In this chapter the prevalence levels will be based on the IOTF international classification scheme, as most survey evidence is available using this approach, and the results tend to be more conservative than some other approaches.1

Prevalence levels

Policy-makers face a second hurdle in understanding the circumstances surrounding obesity in children and adolescents, namely, a lack of representative data on what is happening in the population that is of interest. Only in a few countries are children monitored routinely and data on their nutritional status gathered, analysed and reported consistently.

Even where data are available, they need to be examined carefully. Firstly, data may be collected using proper measurement procedures, or may be self-reported, but self-reported measures tend to underestimate BMI, especially among more over-weight respondents. Data may come from nationally representative surveys or from smaller surveys—for example, in the more accessible urban areas—which do not represent national populations. And, when comparing two surveys across a period of time, surveys need to be properly comparable in terms of the children’s ages, and their ethnic and socio-demographic mix.

The figures presented here are based on the latest and most reliable available, some of which were previously published in 2006 by Wang and Lobstein.5 Unless otherwise stated, the IOTF definitions of over-weight and obesity in childhood are used.

Global figures

Taking an estimate for the world as a whole, in 2004 some 10% of school-age children (aged 5–17) were defined as overweight, including some 2–3% who were obese. This global average reflects a wide range of prevalence levels in different regions and countries, with the prevalence of overweight in Africa and Asia averaging well below 5% and in the Americas and Europe above 20%. Projections to the year 2010 are shown in Table 1.1.

Table 1.1 Estimated prevalence of excess bodyweight in school-age children in 2010.

Source: Wang and Lobstein.

RegionaObeseOverweight (including obese)Americas15%46%Mid East & N Africa12%42%Europe & former USSR10%38%West Pacific7%27%South East Asia5%23%Africa> 1%> 5%

aCountries in each region are according to the World Health Organization.

Region: Americas

The most comprehensive and comparable national representative data on trends in the prevalence of obesity are from the USA, where nationally representative surveys undertaken in the 1960s were followed by the series of National Health and Nutrition Examination Surveys (NHANES) from 1971 onwards. The most recent publications (for surveys conducted in 2003–2004) show that 36% of children aged 6–17 were overweight, including 13% obese. These figures are based on the international (IOTF) criteria for overweight and obesity,12 and compare with 36% and 18% respectively using US-defined cut-offs.14

In Canada 26% of younger children and 29% of older children were found to be overweight in a 2004 survey, almost exactly double the prevalence levels found among children 25 years earlier.15 In Brazil, the prevalence of overweight among school-aged children was 14% in 1997, compared with 4% in 1974. In Chile, in 2000 the prevalence of overweight among school children was 26%.

There are few data available for schoolchildren in most other South and Central American countries, but some data have been collected for pre-school children. In Bolivia, the prevalence of overweight (defined as one standard deviation above a reference mean) was 23% in 1997, and in the Dominican Republic it was 15% in 1996. In a few countries in the region, obesity prevalence has fallen: in Columbia it fell from 5% to 3% between 1986 and 1995.

Region: Europe

A number of studies have examined childhood over-weight and obesity prevalence in European countries. The highest prevalence levels are observed in southern European countries. A survey in 2001 found that 36% of 9-year-olds in central Italy were overweight, including 12% who were obese. In 1991, 21% of school-age children in Greece were overweight or obese, whereas a decade later, in 2000, 26% of boys and 19% of girls in Northern Greece were overweight or obese, while data from Crete in 2002 show 44% of boys aged 15 years to be overweight or obese. In Spain, 35% of boys and 32% of girls aged 13–14 years were overweight in a survey in 2000.

Northern European countries tend to have lower prevalence values. In Sweden in 2000–2001, the prevalence was 18% for children aged 10 years. In the Netherlands the figures are particularly low, with only 10% of children aged 5–17 overweight, including only 2% obese, in a 1997 survey. In France, the figures are a bit higher, at 15% overweight and 3% obese in a northern French survey in 2000, and these figures appear to have remained stable, according to recent preliminary results of surveys in 2007.16 In England, prevalence rates have climbed to 29% overweight, including 10% obese, in a 2004 survey.

The reasons for a north–south gradient are not clear. Genetic factors are unlikely to be the explanation, as the gradient can be shown even within a single country, such as Italy and virtually all countries have shown a marked increase in prevalence in recent decades. A range of factors influencing regional barriers or promoters of population levels of physical activity may be important. The child’s household or family income may be another relevant variable, possibly mediated through income-related dietary factors such as maternal nutrition during pregnancy, or breast- or bottle-feeding in infancy, as well as the quality of the diet during childhood.

Regions: North Africa, Eastern Mediterranean and Middle East

Several countries in this region appear to be showing high levels of childhood obesity. In Egypt, for example, the prevalence of overweight (based on local reference charts and a z score > was over 25% in pre-school children and 14% in adolescents. Similar figures are found in other parts of the region. A fifth of adolescents aged 15–16 years in Saudi Arabia were defined as overweight (based on BMI > 120% reference median value). In Bahrain in 2002, 30% of boys and 42% of girls aged 12–17 were overweight, including over 15% obese in both groups (defined by IOTF cut-offs).

Regions: Asia and Pacific

The prevalence of obesity among pre-school children is around 1% or less in many countries in the region, for example Bangladesh (1.1%), the Philippines (0.8%), Vietnam (0.7%) and Nepal (0.3%), but it should be noted that no data are available for some countries in the region (e.g., the Pacific islands) where adult obesity prevalence rates are known to be high.

In more economically developed countries, the prevalence figures for pre-school and school-age children are considerably higher. Among Australian children and adolescents aged 7–15 years, the prevalence of overweight (including obesity) doubled from 11% to 21% between 1985 and 1995, and was found to be 27% in a regional survey of 4–12-year-olds in 2003–4.17

In mainland China, whose population accounts for one-fifth of the global population, the prevalence of obesity has been rising in both adults and children during the past two decades. A survey in 1992 showed the prevalence of overweight, including obesity, among schoolchildren to be 4%–this rose to 7% in 2002. In urban areas the prevalence was 10%, and in the largest cities nearly 20% (see Table 1.3).

While the epidemic of obesity has affected a wide range of countries in this region, under-nutrition is still a major problem. In China, the prevalence of underweight (<5th percentile BMI of the US reference) was 9% among children aged 6–9 years, and 15% among children aged 10–18, in 1997. In Indonesia, over 25%, and in Bangladesh and India over 45% of children under 5 years old are under-weight. Thus, several of the most populous countries in this region are facing a double burden of continued under-nutrition and rising over-nutrition.

Region: Sub-Saharan Africa

The burden of under-nutrition remains very high in this region, with continuing poverty, war, famine and disease, especially HIV/Aids, and very high rates of child mortality. There are very few surveys from African countries that can provide prevalence figures for childhood obesity, as most public health nutrition programs have been focused on under-nutrition and food safety problems. In general, the prevalence of childhood obesity remains very low in this region, except for countries such as South Africa where obesity has become prevalent in adults, particularly among women, and where childhood obesity is also rising. Data from South Africa show the prevalence of overweight (including obesity) among young people aged 13–19 years to be over 17%, with boys generally less at risk (7%) than girls (25%). Prevalence was highest (over 20% for both boys and girls) in white and Indian population groups.

Trends over time

The prevalence of excess weight among children is increasing in both developed and developing countries, but at different rates and in different patterns. North America and some European countries have the highest prevalence levels, and in recent years have shown high year-on-year increases in prevalence. Data from Brazil and Chile show that rates of increasing overweight among children in some developing countries is comparable to that in the USA or Europe.

Other countries are showing only modest increases. China has shown a small rise in the prevalence of overweight among rural children, but a more marked increase among urban children.18 The rapid rise in the prevalence of overweight is shown in most developed economies, but an interesting exception is Russia, where the economic downturn in the early 1990s may explain the decline in the prevalence of overweight children during the period (Table 1.2).

Table 1.2 Examples of the rise in the prevalence of overweight children in developed and developing economies.

 Date of surveyPrevalence of overweightUSA1971–7414% 1988–9425% 2003–436%Canada1978–7914% 200429%Australia198511% 199521%New Zealand198913% 200030%Japan1976–8010% 1992–200019%England19847% 199412% 200429%Greece (boys)199121%Greece North (boys)200026%Greece Crete (boys)200244%Iceland197812% 199824%Netherlands19805% 1996–9711%Spain198013% 199519% 2000–234%Brazil19744% 199714%Chile198713% 200027%China rural19924% 20025%China urban19927% 200210%Russia199215% 19989% 200512% a

aBased on self-reported height and weight.

Demographics of child adiposity

If policies to prevent child obesity are to be successful they need to consider the distribution of the problem among different demographic groups within the child population. Some population groups are more easily accessed than others but they may not be those most in need of attention. Treatment may be accessed more easily by some groups, but not necessarily by those that need it most.

Examination of differences in the distribution of overweight and obesity among children coming from different social classes (defined by family income levels or educational levels of the main income earner) shows a complex pattern. In more economically developed, industrialized countries, children in lower socio-economic groups tend to show higher prevalence levels of overweight and obesity. Moreover, programmes to tackle obesity may be assisting better-off families while obesity levels continue to rise among poorer families.

In contrast, in countries that are not economically developed, or are undergoing economic development, overweight and obesity levels tend to be highest among families with the highest incomes or educational attainment. In Brazil, in 1997, 20% of children in higher-income families were overweight or obese, compared with 13% of children in middle-income families and only 6% of children in lower-income families. In China, there is a clear positive association between child overweight and both income level and educational level, and by urban–rural differences (Table 1.3).

Table 1.3 Prevalence of overweight and obesity (combined) among children aged 7–12 years in rural and urban populations and various income and education levels defined by parental status, China, 2002.

Source: Li.18

 BoysGirlsUrban/rural  Large city24%15%Small city10%7%Village5%3%Family income (yuan/year/person)  >10,00022%13%5000–10,00015%10%2000–500010%7%<20007%3%Education level of father  College and higher20%12%Senior high school15%9%Junior high school7%5%Primary or less4%2%

These figures need to be considered in developing policies targeting obesity prevention. Economic development in urban and rural areas is likely to be closely related to the development of environments that reduce physical activity, encourage sedentary behavior and encourage the consumption of energy-dense foods and beverages. Physical activity is likely to be highest in rural areas in less developed economies, where there is likely to be only limited access to pre-processed, long-shelf-life, mass-produced products—soft drinks, fatty snack foods, confectionery and fast food outlets—compared with urban areas and among wealthier families. In contrast, in highly-developed economies, the large majority of the population is likely to have less need of physical activity and to have extensive access to processed, energy-dense foods and beverages.

For children, economic development sees a move from agricultural labor and domestic labor to TV watching, while active transport (walking, cycling) is replaced with motorized transport, even for short journeys such as getting from home to school or to shops. Traditional staple foods give way to highly marketed and promoted branded food and beverage products.

When economic development suffers a reversal, as was witnessed in some Eastern European economies and in the Russian Federation during the late 1980s and early 1990s, child overweight levels may actually show decreasing prevalence, as the data for Russia indicate here. A study of children’s body height and mass in Poland from 1930 until 1994 indicated that the lowest values for both traits were found immediately post-war (1948–49), increasing to the end of the 1970s, and falling again during the recession of the 1980s.19 When the economy recovers, the prevalence of overweight and obesity may increase sharply, as has been shown in data for East Germany (school-age children) and Croatia (pre-school children) in the years following unification and national independence, respectively.

Child obesity and tracking to a dulthood

One of the most pressing considerations to emerge from the dramatic rise in child obesity is the likely impact that this will have on adult disease rates in the next few years. The persistence, or tracking, of obesity from childhood and adolescence to adulthood has been well documented.20 In the USA, Whitaker et al21 demonstrated that if a child was obese during childhood, the chance of being obese in young adulthood ranged from 8% for 1- or 2 year-olds without obese parents to 79% for 10–14-year-olds with at least one obese parent. Evidence from a longitudinal study of children, the Bogalusa Heart Study, suggests that children who have overweight onset before the age of 8 are at significantly increased risk of obesity in adulthood.22 Comparing racial groups, tracking of adiposity was stronger for black compared with white youths, especially for females (Table 1.4).23

Table 1.4 Proportion of children who had a BMI > 27.5 kg/m2 as young adults (before age 30 years) according to obesity status in childhood.

Source: Whitaker et al.

In a review of evidence on child adiposity undertaken by the US Preventive Task Force, persistence of overweight was consistently seen in 19 longitudinal studies of children of both genders and all ages, with the greatest likelihood of overweight persistence seen for older children and those most severely overweight, for both genders.24 Parental overweight also substantially increases the risk of child obesity and subsequent adult obesity.

Co-morbidities of child obesity

Besides being a risk factor for adult obesity and chronic disease, excess adiposity in childhood raises the risk of a number of adverse physical and psychosocial health outcomes in childhood itself1,25 summarized in Table 1.5.

Table 1.5 Health problems concurrent with child and adolescent obesity.

EndocrineInsulin resistance/impaired glucose toleranceType 2 diabetesMenstrual abnormalitiesPolycystic ovary syndromeHypercorticolismCardiovascularHypertensionDyslipidaemiaFatty streaksLeft ventricular hypertrophyGastroenterologicalCholelithiasisLiver steatosis /non-alcoholic fatty liverGastro-oesophageal refluxPulmonarySleep apneaAsthmaPickwickian syndromeOrthopedicSlipped capital epiphysesBlount’s disease (tibia vara)Tibial torsionFlat feetAnkle sprainsIncreased risk of fracturesNeurologicalIdiopathic intracranial hypertension (e.g., pseudotumour cerebri)Other physicalSystemic inflammation/raised C-reactive proteinPsycho-socialAnxietyDepressionLow self-esteemSocial discrimination

Figures for the numbers of children affected by co-morbidities are remarkable hard to obtain. BMI or obesity status may not be recorded when diagnoses of ill-health are made in pediatric clinics, while in the population at large the early stages of chronic disease may not be diagnosed among overweight and obese children.

The lack of adequate information can be a significant problem in the planning of pediatric services to respond to the rising levels of child obesity. One estimate, based on clinical surveys in a number of countries, suggests that a substantial proportion of obese children are likely to be affected by one or more concurrent disease indicator, as shown in Table 1.6.

Table 1.6 Estimated prevalence of disease indicators among obese children.

Source: Lobstein and Jackson-Leach.

 Mean95% CIRaised blood triglycerides25.7%21.5%–30.5%Raised total blood cholesterol26.7%22.1%–31.8%High LDL cholesterol22.3%18.9%–26.3%Low HDL cholesterol22.6%18.7%–27.0%Hypertension25.8%21.8%–30.2%Impaired glucose tolerance11.9%8.4%–17.0%Hyperinsulinaemia39.8%33.9%–45.9%Type 2 diabetes1.5%0.5%–4.5%Metabolic syndrome, 3 factors29.2%23.9%–35.3%Metabolic syndrome, 4 factors7.6%4.6%–12.2%Hepatic steatosis33.7%27.9%–41.8%Raised serum aminotransferase16.9%12.8%–22.0%

Note: Definitions of obesity and of the indicators differ between source surveys. Mean and confidence intervals based on weighted averages of survey findings.

Type 2 diabetes

Obesity in childhood is a major risk factor for the development of Type 2 diabetes–a disease that until recently was considered to occur only later in adulthood. The American Diabetes Association’s (ADA) consensus report indicated that up to 85% of children diagnosed with Type 2 diabetes are over-weight or obese at diagnosis.27 Small sample surveys in the USA suggest that up to 3% of clinically obese children may be affected, the majority of them without awareness.26 These patients may present with glycosuria without ketonuria, and absent or mild polyuria and polydipsia.

Impaired glucose tolerance and insulin resistance

Before Type 2 diabetes develops, there is a period of altered glucose metabolism. Oral glucose tolerance testing (OGTT) appears to be more sensitive than fasting blood glucose to detect the pre-diabetic condition of impaired glucose tolerance (IGT). Children with IGT have elevated insulin levels in the fasting state and in response to OGTT. Around 10% of clinically obese children may be affected.27 Central adiposity represents an additional independent risk factor.

Metabolic syndrome and cardiovascular disorders

The metabolic syndrome or insulin-resistance syndrome, is a well-known obesity-associated condition found in at least 20% of all adults in the USA28 and is increasingly observed among obese children and adolescents. The syndrome has a range of definitions, but is usually diagnosed based on the presence of several of the following conditions: abdominal obesity, elevated triglycerides, low high-density lipoprotein (HDL) cholesterol, hypertension and elevated fasting glucose. The overall prevalence among adolescents in the USA in 1999–2000 was estimated to be over 6%,29 and it increased from less than 1% among normal weight adolescents to 10% among those who were overweight, and to more than 30% among those who were obese.

Approximately 4% of normal-weight US adolescents have high blood pressure, while the prevalence rises to over 25% among obese adolescents. Low levels of circulating HDL cholesterol are found among 18% and 39% or normal weight and obese ado lescents, respectively, and high levels of blood triglycerides are found among 17% and 46%, respectively. Results from a study conducted in Hungary suggests that the number of metabolic syndrome components increases with the duration of the obesity.30

Evidence from the Bogalusa Heart Study indicates that atherosclerotic changes are present in blood vessels of even very young children.31 The extent and severity of asymptomatic coronary and aortic disease in young people increases with age, and is strongly correlated with BMI, blood pressure, cholesterol and triglyceride levels.31 Additionally, very overweight children show signs of severe cardiovascular deconditioning in tests of physical fitness, and some already have left ventricular hypertrophy.32 These findings suggest that cardiovascular risk factors present in childhood may not only impact long-term risk, but may also have more immediate consequences, further highlighting the importance of addressing cardiovascular risk factors well before adulthood.31,32

Hyperandrogenism/polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a condition where there is chronic anovulation and evidence of excess androgen, for which there is no other explanation. Although the prevalence of PCOS among adolescents is difficult to determine, girls who are oligomenorrheic and are overweight or obese appear to be at greatest risk for developing PCOS.33 Insulin resistance may be an important underlying factor.

Cholelithiasis

The increase of total body synthesis of cholesterol that occurs in obesity leads to a higher ratio of cholesterol to solubilizing lipids in bile, and predisposes the individual to gallstone formation.34 Although cholelithiasis and cholecystitis are relatively uncommon in children, pediatric hospital discharges for gall bladder disease in the USA have tripled in the period 1980 to 1999.35 Obese children with gall bladder disease may present with non-specific abdominal pain with or without vomiting. Asymptomatic presentations are not uncommon, with gallstones being detected by abdominal ultrasound.

Non-alcoholic fatty liver disease

A further complication of pediatric obesity is non-alcoholic fatty liver disease or liver steatosis. Liver function tests are often abnormal, with greater elevations in aminotransferase (ALT) relative to aspartate aminotransferase (AST). Up to 77% of obese Chinese children referred for medical assessment had radiological evidence of fatty liver disease.36 In a multi-center review of liver biopsies in Boston area hospitals, all 14 children with varying degrees of hepatosteatosis and steatohepatitis were obese.37 In a similar study conducted in Australia, 16 of 17 children with steato-hepatitis were 125–218% of ideal body weight.38 Liver biopsies in these children generally show inflammation and fibrosis, but there have been occasional reports of cirrhosis.38,39 As in adults, improvements in liver function tests have been reported among children who lost weight, and both ALT and BMI have been shown to be strong independent predictors of fatty liver disease.36

Apnea and Asthma

Obstructive sleep apnea, one part of a spectrum of sleep-disordered breathing, is another potentially dangerous consequence of childhood obesity. Two independent studies of obese US children referred for assessment of sleep-associated breathing disorders reported that 37%40 to 94%41 had abnormal polysomnographic findings. All were reported to be snorers and up to 50% had episodes of apnea.

Among US children with asthma, severe obesity is more than twice as prevalent as it is among children without asthma,42 and asthma is about twice as common in obese children compared with non-obese children in studies conducted in Israel, Germany and the USA.43–45 Despite this evidence supporting a cross-sectional association between obesity and asthma in children and adolescents, a recent survey in Canada failed to detect a statistically significant association between obesity and asthma in a large population of 4–11-year-olds.46 Studies differ in their definitions of obesity and/or asthma, and it is plausible that the direction of causation is reversed, with the presence of asthma leading to physical inactivity, which results in weight gain.

Orthopedic/musculoskeletal effects

Excessive body weight in childhood adds mechanical stress to unfused growth plates and bones that are undergoing ossification, making overweight and obese children susceptible to orthopedic abnormalities, namely Blount disease and slipped capital femoral epiphysis. Obese children may also be predisposed to excess fractures, as well as bone and joint pain. Calculations of plantar force and pressure during standing and walking indicate that obese children may be at increased risk of developing foot pain or pathologies.

Psychological effects

Much of the work that has been done in this area is cross-sectional, so that the directionality of the associations is uncertain. However, the stigmatization, bullying and teasing experienced by overweight children may be internalized in feelings of low self-worth, depressive symptoms or suicidal thinking. Whereas one longitudinal study in the USA showed no effect of BMI on self-esteem in adolescents and young adults,47 a second study identified important racial/ethnic differences in the relationship between changes in self-esteem and overweight in girls.48 In Hispanic and white girls, but not among black girls, those who were overweight experienced significant decreases in self-esteem compared with their non-obese counterparts.48 The lack of a similar association for black girls is consistent with an earlier cross-sectional study reporting normal self-esteem among obese inner-city black children, suggesting that, at least in this subgroup, obese children may not be motivated to lose weight by the promise of improved self-esteem.49

Psychosocial effects

Possibly the most pervasive consequences of obesity in many Western societies are psychosocial.50 Cross-sectional associations between obesity risk and bullying, social marginalization and poor academic performance have been documented in studies conducted in Canada, the USA and Sweden.25 Awareness of the stigma associated with obesity can lead to concerns about weight and fear of obesity even in children as young as 5 or 6.50

Adolescent obesity appears to affect socio-economic outcomes: data from the US National Longitudinal Survey of Youth demonstrated that overweight in adolescence and young adulthood may be a significant socio-economic handicap, especially for females.47