Obesity : preventing and managing the global epidemic : report of a WHO consultation.

1. Introduction 1 1.1 Structure of the report 3 1.2 Themes of the report 4 Part I The problem of overweight and obesity 5 2. Defining the problem 6 2.1 Introduction 6 2.2 Why classify overweight and obesity? 7 2.3 Body mass index 8 2.3.1 Use of other cut-off points in the classification of obesity 8 2.3.2 Variation in the relationship between BMI and body fatness 8 2.3.3 Use of BMI to classify obesity 9 2.4 Waist circumference and waist:hip ratio 9 2.5 Additional tools for the assessment of obesity 11 2.6 Classifying obesity in childhood 11 2.6.1 Use of growth charts 11 2.6.2 International childhood reference population 12 2.6.3 BMI-for-age reference curves 12 References 13 3. Global prevalence and secular trends in obesity 16 3.1 Introduction 16 3.2 A note of caution 17 3.3 The WHO MONICA project 17 3.4 African Region 20 3.4.1 Secular trends in obesity 20 3.4.2 Current prevalence of obesity 21 3.5 Region of the Americas 21 3.5.1 Secular trends in obesity 21 3.5.2 Current prevalence of obesity 22 3.6 South-East Asia Region 23 3.6.1 Secular trends in obesity 23 3.6.2 Current prevalence of obesity 24 3.7 European Region 24 3.7.1 Secular trends in obesity 24 3.7.2 Current prevalence of obesity 24 3.8 Eastern Mediterranean Region 25 3.8.1 Secular trends in obesity 25 3.8.2 Current prevalence of obesity 26 3.9 Western Pacific Region 27 3.9.1 Secular trends in obesity 27 3.9.2 Current prevalence of obesity 29 3.10 Body mass index distribution in adult populations 30 3.11 Obesity during childhood and adolescence 31 References 34 Part II Establishing the true costs of the problem of overweight and obesity 38 4 Health consequences of overweight and obesity in adults and children 39 4.1 Introduction 39 4.2 Obesity as a risk factor for noncommunicable diseases 40 4.3 Difficulties in evaluating the health consequences of obesity 40 4.4 Relative risk of obesity-associated health problems 42 4.5 Intra-abdominal (central) fat accumulation and increased risk 43 4.6 Obesity-related mortality 44 4.7 Chronic diseases associated with obesity 46 4.7.1 Cardiovascular disease and hypertension 46 4.7.2 Cancer 48 4.7.3 Diabetes mellitus 49 4.7.4 Gallbladder disease 50 4.8 Endocrine and metabolic disturbances associated with obesity 51 4.8.1 Endocrine disturbances 51 4.8.2 Metabolic disturbances 53 4.9 Debilitating health problems associated with obesity 54 4.9.1 Osteoarthritis and gout 54 4.9.2 Pulmonary diseases 55 4.10 Psychological problems associated with obesity 55 4.10.1 Social bias, prejudice and discrimination 56 4.10.2 Psychological effects 57 4.10.3 Body shape dissatisfaction 57 4.10.4 Eating disorders 57 4.11 Health consequences of overweight and obesity in childhood and adolescence 58 4.11.1 Prevalence 58 4.11.2 Psychosocial effects 59 4.11.3 Cardiovascular risk factors 59 4.11.4 Hepatic and gastric complications 59 4.11.5 Orthopaedic complications 60 4.11.6 Other complications of childhood obesity 60 References 60 5. Health benefits and risks of weight loss 69 5.1 Introduction 69 5.2 Problems in evaluating the effects of long-term weight loss 69 5.3 Weight loss and general health 70 5.3.1 Modest weight loss 70 5.3.2 Extensive weight loss 70 5.4 Weight loss and mortality 70 5.5 Impact of weight loss on chronic disease, and on endocrine and metabolic disturbances 71 5.5.1 Cardiovascular disease and hypertension 71 5.5.2 Diabetes mellitus and insulin resistance 71 5.5.3 Dyslipidaemia 72 5.5.4 Ovarian function 72 5.6 Weight loss and psychosocial functioning 72 5.7 Hazards of weight loss 73 5.8 Weight cycling 74 5.9 Effects of weight loss in obese children and adolescents 74 References " 75 6. Economic costs of overweight and obesity 78 6.1 Introduction 78 6.2 Cost-of-illness studies 79 6.2.1 Uses of cost-of-illness studies 80 6.2.2 Limitations of cost-of-illness studies 80 6.2.3 Steps in undertaking a cost-of-illness study 81 6.2.4 The disability-adjusted life year 83 6.3 International estimates of the cost of obesity 83 6.3.1 Studies in developed countries 83 6.3.2 Studies on the broader economic issues 86 6.3.3 Studies in developing countries 88 6.3.4 Conclusions 88 6.4 Economic costs and benefits of obesity treatment 89 6.4.1 Analyses of obesity-control trials 89 6.4.2 Potential cost savings associated with a reduction in the prevalence of obesity 90 6.4.3 Cost-effectiveness of obesity prevention and treatment 91 References 97 Part III Understanding how overweight and obesity develop 100 7. Factors influencing the development of overweight and obesity 101 7.1 Introduction 101 7.2 Energy balance and the physiological regulation of body weight 102 7.2.1 Fundamental principles of energy balance 102 7.2.2 Physiological regulation of body weight 105 7.2.3 Dynamics of weight gain 105 7.2.4 Implications for public health 107 7.3 Dietary factors and physical activity patterns 108 7.3.1 Dietary factors 108 7.3.2 Physical activity patterns 112 7.4 Environmental and societal influences 118 7.4.1 Changing societal structures 118 7.4.2 Variation within societies 124 7.4.3 Cultural influences 126 7.4.4 Impact of societal changes on food intake and activity patterns 129 7.5 Individual/biological susceptibility 133 7.5.1 Genetic susceptibility 134 7.5.2 Non-genetic biological susceptibility 137 7.5.3 Other factors promoting weight gain 139 7.6 Weight loss 142 References 142 Part IV Addressing the problem of overweight and obesity 153 8. Principles of prevention and management of overweight and obesity 154 8.1 Introduction 154 8.2 Strategies for addressing the problem of overweight and obesity 156 8.3 Prevention strategies 156 8.3.1 Effectiveness 157 Aims 158 Levels of preventive action 160 Integrating obesity prevention into efforts to prevent other noncommunicable diseases 162 8.4 Dealing with individuals with existing overweight and obesity 163 8.4.1 The current situation 164 8.4.2 Knowledge and attitudes of health professionals 164 8.4.3 Improving the situation 166 8.5 Partnerships for action on obesity 167 8.5.1 Shared responsibility 167 8.5.2 Coordination of government policies 170 References 170 9. Prevention and management of overweight and obesity in populations: a public health approach 174 9.1 Introduction 174 9.2 Intervening at the population level 175 9.2.1 Relationship between average population BMI and the level of obesity 176 9.2.2 Optimum population BMIs 178 9.2.3 Will population-based approaches to preventing weight gain lead to increased levels of underweight and eating disorders? 179 9.3 Public health intervention strategies 179 9.3.1 Improving the knowledge and skills of the community 179 9.3.2 Reducing population exposure to an obesity-promoting environment 180 9.4 Priority interventions 180 9.4.1 Increasing physical activity 181 9.4.2 Improving the quality of the diet 181 9.4.3 Measures for use in evaluating obesity-prevention programmes 182 9.5 Results of public health programmes for the control of obesity 183 9.5.1 Countrywide public health programmes 184 9.5.2 Communitywide CHD prevention programmes 184 9.5.3 Programmes targeting factors important in the development of obesity 187 9.5.4 Implications for future public health programmes to control obesity 189 9.6 Lessons to be learned from successful public health campaigns 190 9.7 Public health strategies to improve the prevention and management of obesity 190 9.7.1 Developed countries 192 9.7.2 Developing and newly industrialized countries 192 References 194 vi 10. Prevention and management of overweight and obesity in at-risk individuals: an integrated health-care services approach in community settings 197 10.1 Introduction 197 10.2 Management strategies for at-risk individuals and groups 198 10.2.1 Prevention of weight gain 198 10.2.2 Weight maintenance 200 10.2.3 Management of obesity comorbidities 200 10.2.4 Weight loss 201 10.3 A health-care services approach to the new concept of weight management 203 10.3.1 Recruitment and referral 203 10.3.2 Comprehensive health assessment 204 10.3.3 Setting appropriate targets 205 10.3.4 Selection and implementation of appropriate management strategies 206 10.3.5 Monitoring, rewards and evaluation 208 10.4 Patient support in obesity treatment 208 10.4.1 Support within the health-care service 209 10.4.2 Involvement of family 209 10.4.3 Self-help and support groups 210 10.4.4 Commercial weight-loss organizations 210 10.5 Treatment of obesity 211 10.5.1 Dietary management 211 10.5.2 Physical activity and exercise 213 10.5.3 Behaviour modification 215 10.5.4 Drug treatment 217 10.5.5 Gastric surgery 221 10.5.6 Traditional medicine 223 10.5.7 Other treatments 223 10.6 Management of obesity in childhood and adolescence 224 10.6.1 Evidence that treatment of childhood obesity prevents later adult obesity 224 10.6.2 Treatment of overweight and obese children 226 10.6.3 Obesity-management programmes for children 228 References 231 Part V Challenges for the new millennium 239 11. Conclusions and recommendations 240 11.1 General conclusions 240 11.2 Recommendations 241 11.2.1 Defining the problem of overweight and obesity 241 11.2.2 Establishing the true costs of the problem of overweight and obesity 243 11.2.3 Understanding how the problem of overweight and obesity develops 245 11.2.4 Addressing the problem of overweight and obesity 247 Acknowledgements 251 Annex Criteria for evaluating commercial institutions involved in weight loss