Obesity: diagnosis, prevention, and treatment; evidence based answers to common questions

Diet, wheeze, and atopy in school children in Menorca, Spain

Epidemiological studies have shown inverse associations of asthma symptoms with fish, vegetable, and fruit intake. We evaluated the association between several dietary factors with wheeze and atopy among children in Menorca, a Spanish Mediterranean island. A cross-sectional analysis was performed on 460 children at age 6.5 yr. Parents completed a questionnaire on the child's respiratory and allergic symptoms, and a 96-item food frequency questionnaire. Children underwent skin prick tests with six common aeroallergens. The average daily intake was relatively high for fruits (177 g) and fish (54 g), and moderate for vegetables (59 g). A high consumption (>40 g/day) of fruity vegetables (tomatoes, eggplants, cucumber, green beans, zucchini) was found to have beneficial effect on current wheeze [odds ratio (OR), 0.38; 95% confidence interval (CI), 0.15-0.95, p < 0.05], and atopic wheeze with a significant decreasing trend when intake was increased (OR, 0.19; 95% CI, 0.04-0.95, p for trend = 0.04). No other fruits or vegetables were significantly associated with wheeze or atopy prevalence. An inverse association was found between a fish intake > or =60 g/day and atopy (OR, 0.43; 95% CI, 0.21-0.90, p < 0.05). The associations remained significant after adjustment for energy intake and maternal diet during pregnancy. Our results support a potential protective effect of fruity vegetables and fish intake during childhood on wheeze and atopy respectively.

Obesity prevention: necessary and possible. A structured approach for effective planning

Obesity is a serious public health problem that has important social, economic and health consequences. The prevalence of obesity is rising rapidly throughout the world in both rich and poor countries, and it affects all sections of society. There are several important reasons for addressing the prevention of obesity, rather than its treatment or management. The prevention of weight gain (or the reversal of small gains) and the maintenance of a healthy weight are likely to be easier, less expensive and potentially more effective than the treatment of obesity after it has fully developed. A structured planning framework for the identification of potential interventions for the promotion of healthy weight and the prevention of weight gain is clearly required. However, detailed reviews of the scientific literature have revealed that the body of research is too small to provide firm guidance on consistently-effective interventions for adults or children. Ultimately, a broader approach to evidence of effectiveness needs to be adopted. The present paper proposes a structured planning approach that utilises the portfolio model and allows the selection of interventions to be based on the best available evidence, while not excluding untried but promising strategies.

Physical activity interventions in the prevention and treatment of paediatric obesity: systematic review and critical appraisal

Interventions for prevention and treatment of childhood obesity typically target increases in physical activity and, more recently, reductions in physical inactivity (sedentary behaviour such as television viewing). However, the evidence base for such strategies is extremely limited. The main aim of the present review was to update the systematic review and critical appraisal of evidence in the light of the recent rapid expansion of research in this area. Randomised controlled trials (RCT) that targeted activity or inactivity, that followed up children or adolescents for at least 1 year and that included an objective weight-related outcome measure were included. Trials were appraised using previously published criteria (Harbour & Miller, 2001), and literature search strategies described previously (Reilly et al. 2002) were updated to May 2002. A total of four new RCT, two new systematic reviews and one meta-analysis were identified. The evidence base has increased markedly since the completion of earlier reviews, although high-quality evidence is still lacking. The evidence on childhood obesity prevention is not encouraging, although promising targets for prevention are now clear, notably reduction in sedentary behaviour. There is stronger evidence that targeting activity and/or inactivity might be effective in paediatric obesity treatment, but doubts as to the generalisability of existing interventions, and the clinical relevance of the interventions is unclear. Further research in settings outside the USA is urgently needed, and two ongoing RCT in Scotland are summarised.

Dietary intake, physical activity and TV viewing as mediators of the association of socioeconomic status with body composition: a cross-sectional analysis of Australian youth

BACKGROUND

There is emerging evidence of socioeconomic gradients in adiposity among Australian youth. Behavioral mechanisms for these trends are unexplained.

METHODS

In total, 194 South Australian children (97 boys, 11.48+/-0.43 years; 97 girls, 11.60+/-0.38 years) were assessed for pubertal status, stature, weight, skinfolds and waist girth. Socioeconomic status (SES) was represented by postcode of residence (Socioeconomic Index for Areas) and parent education. Children reported moderate-to-vigorous physical activity (MVPA), TV viewing (TV) and dietary intake (daily energy intake as a ratio of predicted basal metabolic rate (DEI/BMR); and fat intake), using three x 24 h recall. Path analysis (partial least-squared method) was used to analyze the independence and interdependence of pathways linking SES, anthropometric variables and measured behaviors.

RESULTS

SES was negatively associated with waist girth and skinfolds in girls, and waist girth in boys. In models including behavioral variables, these SES gradients in girls were largely unattenuated; accordingly, physical activity and dietary intake were not confirmed as mediators of the association of SES and girls' adiposity. In boys there was evidence that the negative relationship between SES and waist girth was mediated by fat intake.

CONCLUSIONS

The inverse relationships between SES and girls' adiposity were unexplained by the behavioral attributes measured in this study. Mediators of SES gradients in youth adiposity remain elusive, and may require intensive methodologies to explicate.

Childhood obesity prevention studies: lessons learned and to be learned

Objective

To provide an overview of methodological issues in the design, delivery and evaluation of childhood obesity prevention programmes.

Design

Review of existing literature.

Setting

International.

Results

Interventions have varied considerably with regard to their design, subject selection criteria, sample size, attrition rates, intervention components and duration of both the intervention and the follow-up phases. However, overall, there is only a limited body of consistent, high-quality evidence on which valid and generalisable conclusions can be drawn about best practices for the prevention of childhood obesity.

Conclusions

Although the rationale for targeting children and adolescents through primary prevention is now compelling, effective obesity prevention remains elusive. There is increasing consensus that prevention of childhood obesity necessitates multifaceted health promotion interventions based on population health principles. By definition, such interventions should have a range of outcome indicators of effectiveness, generalisability and sustainability, not just the traditional ones focused on individual lifestyle behaviour change. Given the complexity and intricacy of population-based intervention programmes, multiple methods of data collection which combine both qualitative and quantitative approaches will need to be fully exploited in order to move towards evidence-based practice in the future.

Physical activity to prevent obesity in young children: cluster randomised controlled trial

OBJECTIVE

To assess whether a physical activity intervention reduces body mass index in young children.

DESIGN

Cluster randomised controlled single blinded trial over 12 months.

SETTING

Thirty six nurseries in Glasgow, Scotland.

PARTICIPANTS

545 children in their preschool year, mean age 4.2 years (SD 0.2) at baseline.

INTERVENTION

Enhanced physical activity programme in nursery (three 30 minute sessions a week over 24 weeks) plus home based health education aimed at increasing physical activity through play and reducing sedentary behaviour.

MAIN OUTCOME MEASURE

Body mass index, expressed as a standard deviation score relative to UK 1990 reference data. Secondary measures were objectively measured physical activity and sedentary behaviour; fundamental movement skills; and evaluation of the process.

RESULTS

Group allocation had no significant effect on the primary outcome measure at six and 12 months or on measures of physical activity and sedentary behaviour by accelerometry. Children in the intervention group had significantly higher performance in movement skills tests than control children at six month follow-up (P=0.0027; 95% confidence interval 0.3 to 1.3) after adjustment for sex and baseline performance.

CONCLUSIONS

Physical activity can significantly improve motor skills but did not reduce body mass index in young children in this trial.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN36363490.

Tackling the obesity epidemic: new approaches

Perspective on the paper by Rudolf et al (see page 736)

Evidence for prescribing exercise as therapy in chronic disease

Considerable knowledge has accumulated in recent decades concerning the significance of physical activity in the treatment of a number of diseases, including diseases that do not primarily manifest as disorders of the locomotive apparatus. In this review we present the evidence for prescribing exercise therapy in the treatment of metabolic syndrome-related disorders (insulin resistance, type 2 diabetes, dyslipidemia, hypertension, obesity), heart and pulmonary diseases (chronic obstructive pulmonary disease, coronary heart disease, chronic heart failure, intermittent claudication), muscle, bone and joint diseases (osteoarthritis, rheumatoid arthritis, osteoporosis, fibromyalgia, chronic fatigue syndrome) and cancer, depression, asthma and type 1 diabetes. For each disease, we review the effect of exercise therapy on disease pathogenesis, on symptoms specific to the diagnosis, on physical fitness or strength and on quality of life. The possible mechanisms of action are briefly examined and the principles for prescribing exercise therapy are discussed, focusing on the type and amount of exercise and possible contraindications.

Obesity in childhood and adolescence: evidence based clinical and public health perspectives

A global epidemic of paediatric obesity occurred in recent years, and prevalence of obesity is continuing to rise. In the developed world obesity is now the most common disease of childhood and adolescence. Paediatric obesity is not a cosmetic issue, being associated with a significant burden of ill health both for obese children and for adults who were obese as children. Health professionals tend to underestimate the impact of paediatric obesity, and lack the skills, knowledge, and time to treat it effectively. This short review aims to summarise recent systematic reviews on the origins, consequences, prevention, and treatment of paediatric obesity.

The effect of a medium-term activity- and diet-induced energy deficit on subjective appetite sensations in obese children

OBJECTIVE

To assess the subjective appetite responses to an imposed activity- and diet-induced energy deficit during a residential intervention programme for obese children.

DESIGN

A 6-week intervention of fixed, reduced dietary intake and 6 h/day of skill-based physical activity while resident in a weight loss camp.

SUBJECTS

Thirty-eight obese (mean body mass index (BMI)=34.9 kg m(-2)) boys and girls (mean age 13.9+/-1.57).

MEASUREMENTS

An electronic appetite rating system (EARS) was used to periodically measure subjective appetite sensations at the start (WK1) and at the end (WK6) of the camp. Subjective ratings of hunger and fullness were compared at the start and end of 6 weeks of an activity- and diet-induced-based weight loss intervention.

RESULTS

At the end of the 6 weeks, the children had lost 8.4 kg in body mass. The diurnal profiles of subjective appetite sensations demonstrated clear oscillations in hunger and fullness. There was a significant increase in hunger (P<0.0001) and decrease in fullness (P<0.005) at the end (WK6) of the medium-term energy deficit. In WK6, morning ratings of hunger were higher than in WK1 (P<0.005) and the fixed energy evening meal induced a lower suppression of hunger (P<0.02).

CONCLUSION

A programme of fixed, reduced-dietary intake combined with an activity and behavioural programme was successful at inducing a significant reduction in body mass in obese children. Subjective sensations of appetite were sensitive to a medium-term negative energy balance and weight loss. These data are essential as we continue to evolve methods of treatment for overweight and obese children.

Body mass, fat distribution and blood pressure in Southern Italian children: results of the ARCA project

OBJECTIVE

To investigate the association between the degree of adiposity, assessed using the international reference values for body mass index (BMI) of the International Obesity Task Force (IOTF), the fat distribution pattern and the blood pressure (BP) profile in children.

METHODS

Anthropometric indices and blood pressure were measured in 3923 children aged 6-11 years in southern Italy.

RESULTS

The prevalence of overweight and obesity (by IOTF references) and pediatric hypertension was, respectively: 27, 21 and 10% for boys; 25, 21 and 14% for girls. Body mass index and waist z-scores were the strongest determinants of BP by regression analysis. Overweight and obesity were associated with a greater tendency for central fat deposition and higher BP (waist, cm; boys: 59.2+/-6.0, 69.5+/-7.9, 79.0+/-9.7; girls: 58.8+/-6.5, 68.2+/-7.4, 75.3+/-8.9; SBP/DBP, mmHg; boys: 94/60+/-12/9, 99/62+/-13/8, 103/64+/-15/10; girls: 93/59+/-12/9, 99/62+/-14/9, 101/63+/-14/9; normal weight, overweight and obese, respectively; P<0.0001; M+/-SD), and a higher risk of hypertension (overweight: RR=2.33; 95% CI 1.76-3.08; obesity: RR=3.69; 95% CI 2.78-4.90), independent of age, physical activity, birth weight, parental adiposity and education. Among normal weight children, 99% had waist <85th percentile and 93% were normotensive.

CONCLUSIONS

Overweight and obese children, identified according to the IOTF growth charts, are characterized by a central fat distribution pattern and higher BP.

Childhood obesity: a growing public health concern

Childhood obesity has been deemed epidemic, a term usually reserved for infectious diseases that sweep populations. This review begins with guidance regarding obesity definitions and a review of the data on global prevalence. The next section details the myriad health consequences for immediate and long-term physical and psychosocial health outcomes. The authors then discuss what is known regarding distal and proximal causes and correlates at the individual and contextual levels of family, health care, schools and community. The final sections provide a summary of interventions in diverse settings and some current thinking on how the field is likely to evolve over the next several years.

Perceived effectiveness and side effects of intermaxillary fixation for diet control

Weight loss is one of the major side effects associated with intermaxillary fixation (IMF) following orthognathic surgery or jaw fractures. The aim of this study was to retrospectively interview patients treated with intermaxillary fixation for diet control (IMFDC) to collect base-line information regarding: (1) perceived effectiveness, patients' compliance and patients' satisfaction with the treatment; (2) the frequency of side effects associated with IMFDC. The results show that IMFDC significantly reduced weight by a mean of 6.8 kg during treatment, and a mean of 4.1 kg at a minimum of 1 month following IMFDC removal (P<0.0001). Only 32.5% of the patients complied with the planned period of IMFDC treatment while 70% were satisfied with the treatment results. The most common side effects were speech problems and oral-facial pain with a prevalence of 52.5 and 32.5%, respectively. IMFDC treatment is not effective for long-term weight reduction and may only be used for a very short period of time to initiate weight loss. Exercise and/or special diet programs are healthier and better means to treat obesity and maintain weight loss.

Reducing obesity and related chronic disease risk in children and youth: a synthesis of evidence with 'best practice' recommendations

Childhood obesity is a global epidemic and rising trends in overweight and obesity are apparent in both developed and developing countries. Available estimates for the period between the 1980s and 1990s show the prevalence of overweight and obesity in children increased by a magnitude of two to five times in developed countries (e.g. from 11% to over 30% in boys in Canada), and up to almost four times in developing countries (e.g. from 4% to 14% in Brazil). The goal of this synthesis research study was to develop best practice recommendations based on a systematic approach to finding, selecting and critically appraising programmes addressing prevention and treatment of childhood obesity and related risk of chronic diseases. An international panel of experts in areas of relevance to obesity provided guidance for the study. This synthesis research encompassed a comprehensive search of medical/academic and grey literature and the Internet covering the years 1982-2003. The appraisal approach developed to identify best practice was unique, in that it considered not only methodological rigour, but also population health, immigrant health and programme development/evaluation perspectives in the assessment. Scores were generated based on pre-determined criteria with programmes scoring in the top tertile of the scoring range in any one of the four appraisal categories included for further examination. The synthesis process included identification of gaps and an analysis and summary of programme development and programme effectiveness to enable conclusions to be drawn and recommendations to be made. The results from the library database searches (13,158 hits), the Internet search and key informant surveys were reduced to a review of 982 reports of which 500 were selected for critical appraisal. In total 158 articles, representing 147 programmes, were included for further analysis. The majority of reports were included based on high appraisal scores in programme development and evaluation with limited numbers eligible based on scores in other categories of appraisal. While no single programme emerged as a model of best practice, synthesis of included programmes provided rich information on elements that represent innovative rather than best practice under particular circumstances that are dynamic (changing according to population subgroups, age, ethnicity, setting, leadership, etc.). Thus the findings of this synthesis review identifies areas for action, opportunities for programme development and research priorities to inform the development of best practice recommendations that will reduce obesity and chronic disease risk in children and youth. A lack of programming to address the particular needs of subgroups of children and youth emerged in this review. Although immigrants new to developed countries may be more vulnerable to the obesogenic environment, no programmes were identified that specifically targeted their potentially specialized needs (e.g. different food supply in a new country). Children 0-6 years of age and males represented other population subgroups where obesity prevention programmes and evidence of effectiveness were limited. These gaps are of concern because (i) the pre-school years may be a critical period for obesity prevention as indicated by the association of the adiposity rebound and obesity in later years; and (ii) although the growing prevalence of obesity affects males and females equally; males may be more vulnerable to associated health risks such as cardiovascular disease. Other gaps in knowledge identified during synthesis include a limited number of interventions in home and community settings and a lack of upstream population-based interventions. The shortage of programmes in community and home settings limits our understanding of the effectiveness of interventions in these environments, while the lack of upstream investment indicates an opportunity to develop more upstream and population-focused interventions to balance and extend the current emphasis on individual-based programmes. The evidence reviewed indicates that current programmes lead to short-term improvements in outcomes relating to obesity and chronic disease prevention with no adverse effects noted. This supports the continuation and further development of programmes currently directed at children and youth, as further evidence for best practice accumulates. In this synthesis, schools were found to be a critical setting for programming where health status indicators, such as body composition, chronic disease risk factors and fitness, can all be positively impacted. Engagement in physical activity emerged as a critical intervention in obesity prevention and reduction programmes. While many programmes in the review had the potential to integrate chronic disease prevention, few did; therefore efforts could be directed towards better integration of chronic disease prevention programmes to minimize duplication and optimize resources. Programmes require sustained long-term resources to facilitate comprehensive evaluation that will ascertain if long-term impact such as sustained normal weight is maintained. Furthermore, involving stakeholders in programme design, implementation and evaluation could be crucial to the success of interventions, helping to ensure that needs are met. A number of methodological issues related to the assessment of obesity intervention and prevention programmes were identified and offer insight into how research protocols can be enhanced to strengthen evidence for obesity interventions. Further research is required to understand the merits of the various forms in which interventions (singly and in combination) are delivered and in which circumstances they are effective. There is a critical need for the development of consistent indicators to ensure that comparisons of programme outcomes can be made to better inform best practice.

Characterisation of morbidity in a UK, hospital based, obesity clinic

AIM

To identify clinical features which predict those most at risk of co-morbidities within an obesity clinic.

METHODS

Children attending an obesity clinic had fasting glucose, insulin, and lipids measured prior to a standard oral glucose tolerance test (OGTT). History and examination established birth weight, family history of type 2 diabetes/obesity, pubertal status, and presence of acanthosis nigricans. Central and total fat mass was estimated by bio-impedance.

RESULTS

Of the 126 children evaluated, 10.3% (n = 13) had impaired glucose tolerance (IGT); the majority (n = 11) of these would not have been identified on fasting glucose alone. Those with IGT were more likely to have a parental history of type 2 diabetes (relative risk 3.5). IGT was not associated with acanthosis nigricans. Twenty five per cent (n = 19) of those evaluated (n = 75) had evidence of the "metabolic syndrome" (MS). HDL cholesterol and triglyceride levels were related to insulin sensitivity (HOMA-R); HDL cholesterol was also related to birth weight SDS. We observed a trend for those with MS to have a lower birth weight SDS. The severity of obesity did not influence the likelihood of IGT or MS.

CONCLUSIONS

Significant numbers of obese children have associated co-morbidities. Analysis of fasting blood glucose samples alone is not satisfactory to adequately evaluate glucose homoeostasis. The overall level of obesity does not predict co-morbidities. Special attention should be given to those with parental diabetes and a history of low birth weight who are more likely to have IGT and abnormal lipid profiles respectively.

Descriptive epidemiology and health consequences of childhood obesity

Obesity is now the most common disorder of childhood in the developed world, and its prevalence is still increasing. A large body of high-quality and consistent evidence shows that it is best defined using the body mass index (BMI) percentile relative to national BMI reference data. This definition diagnoses excessive fatness adequately, and denotes increased risk of adverse health outcomes. Future research may provide improved obesity definitions for epidemiological use, so that the obesity epidemic can be monitored more effectively. Paediatric obesity causes ill health in both childhood and adulthood, though further research is required on the economic consequences, on some of the co-morbidities in childhood (notably psychological morbidity), and in adulthood where the amount of empirical evidence on long-term effects is limited. The combination of high prevalence with adverse consequences has created a public health crisis.

Interventions for preventing obesity in children

BACKGROUND

Obesity prevention is an international public health priority. The prevalence of obesity and overweight is increasing in child populations throughout the world, impacting on short and long-term health. Obesity prevention strategies for children can change behaviour but efficacy in terms of preventing obesity remains poorly understood.

OBJECTIVES

To assess the effectiveness of interventions designed to prevent obesity in childhood through diet, physical activity and/or lifestyle and social support.

SEARCH STRATEGY

MEDLINE, PsycINFO, EMBASE, CINAHL and CENTRAL were searched from 1990 to February 2005. Non-English language papers were included and experts contacted.

SELECTION CRITERIA

Randomised controlled trials and controlled clinical trials with minimum duration twelve weeks.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Twenty-two studies were included; ten long-term (at least 12 months) and twelve short-term (12 weeks to 12 months). Nineteen were school/preschool-based interventions, one was a community-based intervention targeting low-income families, and two were family-based interventions targeting non-obese children of obese or overweight parents. Six of the ten long-term studies combined dietary education and physical activity interventions; five resulted in no difference in overweight status between groups and one resulted in improvements for girls receiving the intervention, but not boys. Two studies focused on physical activity alone. Of these, a multi-media approach appeared to be effective in preventing obesity. Two studies focused on nutrition education alone, but neither were effective in preventing obesity. Four of the twelve short-term studies focused on interventions to increase physical activity levels, and two of these studies resulted in minor reductions in overweight status in favour of the intervention. The other eight studies combined advice on diet and physical activity, but none had a significant impact. The studies were heterogeneous in terms of study design, quality, target population, theoretical underpinning, and outcome measures, making it impossible to combine study findings using statistical methods. There was an absence of cost-effectiveness data.

AUTHORS' CONCLUSIONS

The majority of studies were short-term. Studies that focused on combining dietary and physical activity approaches did not significantly improve BMI, but some studies that focused on dietary or physical activity approaches showed a small but positive impact on BMI status. Nearly all studies included resulted in some improvement in diet or physical activity. Appropriateness of development, design, duration and intensity of interventions to prevent obesity in childhood needs to be reconsidered alongside comprehensive reporting of the intervention scope and process.

[Prevalence of obesity in 14-year-olds in four primary care centers. Trends in weight changes since the age of two years old]

INTRODUCTION

Childhood obesity is an increasingly common diagnosis in western society and is related to certain changes in lifestyle. Because of its persistence in adulthood and its relationship with several pathological entities such as cardiovascular disease and diabetes, it has become one of the most important problems in children's health. The objective of this study was to determine the prevalence of obesity and overweight in 14-year-old adolescents attending the pediatric outpatient clinics of a primary care center in 2003, and their weight changes from the age of two years old.

SUBJECTS AND METHODS

A long-term study of 277 children born in 1989 was performed. Their body mass index (BMI) was calculated at the age of 2,3,4,6,8,11 and 14 years. Obesity was defined as a BMI > P95 and overweight as a BMI > P85 according to the Centers for Disease Control and Prevention (CDC) growth charts 2000.

RESULTS

The prevalence of obesity in 14 year-olds was 13.2% (15.2% in boys and 11.5% in girls). The prevalence of overweight was 17.4% (18.7% in boys and 16.2% in girls). Gender differences were not significant in any of the age groups studied.

CONCLUSIONS

The prevalence of obesity and overweight in 14 year-old adolescents in our centers is considerable and is similar to that reported in other Spanish regions. The pediatric outpatient clinics of primary care centers should play an active role in the control and prevention of obesity.

Screening and interventions for childhood overweight: a summary of evidence for the US Preventive Services Task Force

BACKGROUND

Childhood and adolescent overweight and obesity are related to health risks, medical conditions, and increased risk of adult obesity, with its attendant effects on morbidity and mortality rates. The prevalence of childhood overweight and obesity has more than doubled in the past 25 years. Purpose. This evidence synthesis examines the evidence for the benefits and harms of screening and early treatment of overweight among children and adolescents in clinical settings.

METHODS

We developed an analytic framework and 7 key questions representing the logical evidence connecting screening and weight control interventions with changes in overweight and behavioral, physiologic, and health outcomes in childhood or adulthood. We searched the Cochrane Library from 1996 to April 2004. We searched Medline, PsycINFO, DARE, and CINAHL from 1966 to April 2004. One reviewer abstracted relevant information from each included article into standardized evidence tables, and a second reviewer checked key elements. Two reviewers quality-graded each article with US Preventive Services Task Force criteria.

RESULTS

Although BMI is a measure of relative weight rather than adiposity, it is recommended widely for use among children and adolescents to determine overweight and is the currently preferred measure. The risk of adult overweight from childhood overweight provides the best available evidence to judge the clinical validity of BMI as an overweight criterion for children and adolescents. BMI measures in childhood track to adulthood moderately or very well, with stronger tracking seen for children with >or=1 obese parent and children who are more overweight or older. The probability of adult obesity (BMI of >30 kg/m(2)) is >or=50% among children >13 years of age whose BMI percentiles meet or exceed the 95th percentile for age and gender. BMI-based overweight categorization for individuals, particularly for racial/ethnic minorities with differences in body composition, may have limited validity because BMI measures cannot differentiate between increased weight for height attributable to relatively greater fat-free mass (muscle, bone, and fluids) and that attributable to greater fat. No trials of screening programs to identify and to treat childhood overweight have been reported. Limited research is available on effective, generalizable interventions for overweight children and adolescents that can be conducted in primary care settings or through primary care referrals.

CONCLUSIONS

BMI measurements of overweight among older adolescents identify those at increased risk of developing adult obesity. Interventions to treat overweight adolescents in clinical settings have not been shown to have clinically significant benefits, and they are not widely available. Screening to categorize overweight among children under age 12 or 13 who are not clearly overweight may not provide reliable risk categorization for adult obesity. Screening in this age group is compromised by the fact that there is little generalizable evidence for primary care interventions. Because existing trials report modest short- to medium-term improvements (approximately 10-20% decrease in percentage of overweight or a few units of change in BMI), however, overweight improvements among children and adolescents seem possible.

Early life risk factors for obesity in childhood: cohort study

OBJECTIVE

To identify risk factors in early life (up to 3 years of age) for obesity in children in the United Kingdom.

DESIGN

Prospective cohort study.

SETTING

Avon longitudinal study of parents and children, United Kingdom.

PARTICIPANTS

8234 children in cohort aged 7 years and a subsample of 909 children (children in focus) with data on additional early growth related risk factors for obesity.

MAIN OUTCOME MEASURES

Obesity at age 7 years, defined as a body mass index (3) 95th centile relative to reference data for the UK population in 1990.

RESULTS

Eight of 25 putative risk factors were associated with a risk of obesity in the final models: parental obesity (both parents: adjusted odds ratio, 10.44, 95% confidence interval 5.11 to 21.32), very early (by 43 months) body mass index or adiposity rebound (15.00, 5.32 to 42.30), more than eight hours spent watching television per week at age 3 years (1.55, 1.13 to 2.12), catch-up growth (2.60, 1.09 to 6.16), standard deviation score for weight at age 8 months (3.13, 1.43 to 6.85) and 18 months (2.65, 1.25 to 5.59); weight gain in first year (1.06, 1.02 to 1.10 per 100 g increase); birth weight, per 100 g (1.05, 1.03 to 1.07); and short (< 10.5 hours) sleep duration at age 3 years (1.45, 1.10 to 1.89).

CONCLUSION

Eight factors in early life are associated with an increased risk of obesity in childhood.

Obesity and the African-American Adolescent in Mississippi: An Overview

Obesity is one of the most common conditions seen in medical practice, and is one of the most difficult to treat. This condition is often perceived as a cosmetic problem, but it is associated with a number of chronic medical conditions including, but not limited to, heart disease, hypertension, and dyslipidemia. Youth obesity has increased at an alarming rate in the United States and in other developed countries around the world. Given the high prevalence of obesity among adults in the United States, it is not surprising that pediatric obesity is also on the rise. The current trends in obesity among African-American adolescents in the state of Mississippi remain alarming and disheartening. Since obesity starts in early childhood and extends into the adolescent years and possibly into adulthood, behavior modification is the key to preventing the onset of obesity in all population groups.

Prevalence of the insulin resistance syndrome in obesity

AIMS

To assess prevalence of the insulin resistance syndrome (IRS: obesity, abnormal glucose homoeostasis, dyslipidaemia, and hypertension) in obese UK children and adolescents of different ethnicities and to assess whether fasting data is sufficient to identify IRS in childhood obesity.

METHODS

A total of 103 obese (BMI >95th centile) children and adolescents 2-18 years of age referred for assessment underwent an oral glucose tolerance test, measurement of fasting lipids, and blood pressure determination. Main outcome measures were prevalence of components of IRS by modified WHO criteria, with IRS defined as > or =3 components (including obesity).

RESULTS

There were 67 girls (65%). BMI z-score ranged from 1.65 to 6.15, with 72% having a z-score > or =3.0. Abnormal glucose homoeostasis was identified in 46% (hyperinsulinism in 40%, impaired fasting glucose in 0.8%, impaired glucose tolerance in 11%). No subjects had silent type 2 diabetes. Dyslipidaemia was identified in 30% and hypertension in 32%. Thirty one per cent had obesity alone, 36% had two components, 28% had three, and 5% had all four components. Birth weight, BMI, and family history of IRS were not associated with risk of IRS. Higher age increased the risk of IRS; however the syndrome was seen in 30% of children under 12 years. The use of fasting glucose and insulin data for identifying IRS had a sensitivity of 88% and specificity of 100%.

CONCLUSIONS

One third of obese children and adolescents have the IRS; however type 2 diabetes is rare. Obese children with the IRS may form a high risk group to whom scarce intervention resources should be targeted. Further work is needed to develop appropriate screening programmes for IRS components in significantly obese children.

Sensitivity and specificity of classification systems for fatness in adolescents

BACKGROUND

Various body mass index (BMI) standards have been proposed for defining overweight in adolescence, but few studies have evaluated their diagnostic accuracy.

OBJECTIVE

We compared the sensitivity and specificity of BMI-based classification systems for detecting excess fatness in adolescents.

DESIGN

A cross-sectional analysis of 474 adolescents aged 17 y was used. Body composition was measured by using densitometry. The international BMI-based systems recommended by the International Obesity Task Force and the World Health Organization were evaluated on the basis of their sensitivity and specificity for detecting excess body fat. Receiver operating characteristic analysis was performed to derive cutoffs to maximize the sum of sensitivity and specificity. True positives were defined by using the percentage body fat cutoffs proposed by Williams et al (Am J Public Health 1992;82:358-63).

RESULTS

For both classification systems, the specificity for overweight was high for both sexes (0.95-1.00). The sensitivity was fairly high for the males (0.72-0.84) but was very low for the females (0.22-0.25). For the males, a BMI cutoff equal to the 85th percentile on a Swedish BMI reference chart maximized the sum of sensitivity and specificity while having both high sensitivity (0.92) and high specificity (0.92). For the females, larger tradeoffs in specificity were needed to improve sensitivity. The mean (+/-SE) areas under the receiver operating characteristic curves for the males and the females were 0.97 +/- 0.02 and 0.85 +/- 0.02, respectively.

CONCLUSIONS

Recommended international classification systems have very high specificity, which results in few cases of non-overweight adolescents being mislabeled as overweight. However, the sensitivity is very low in female adolescents. Thus, many overweight female adolescents could be missed in intervention programs that use the proposed international BMI cutoffs as selection criteria.

The effectiveness of physical activity interventions for the treatment of overweight and obesity and type 2 diabetes

This review summarises current evidence relating to the effectiveness of physical activity (PA) interventions for treating overweight and obesity and type 2 diabetes. Interventions to increase PA for the treatment of overweight and obesity in both children and adults have primarily consisted of health education and behaviour modification strategies in clinical settings or with selected families or individuals. Although evidence is limited, strategies to reduce sedentary behaviours appear to have potential for reducing obesity among children and adolescents. Among adults, strategies that combine diet and PA are more effective than PA strategies alone. Combined lifestyle strategies are most successful for maintained weight loss, although most programs are unsuccessful in producing long-term changes. There is little evidence about compliance to prescribed behaviour changes or the factors that promote or hinder compliance to lifestyle changes. Limited evidence suggests that continued professional contact and self-help groups can help sustain weight loss. Most of the interventions for the treatment of type 2 diabetes have been conducted in clinical settings and have typically required the use of extensive resources. Evidence suggests that interventions can lead to small but clinically meaningful improvements in glycaemic control, even in the absence of weight loss. A recent study demonstrated that a multifactorial intervention (diet, PA and pharmaceutical) can reduce the risk of diabetes complications in individuals with type 2 diabetes. Nevertheless, there is little evidence about the effectiveness of community-based interventions in producing long-term changes in glycaemic control and reduced mortality in people with type 2 diabetes.

Discrepancies between classification systems of childhood obesity

Despite growing concern about weight-related problems among children, no universally accepted classification system for childhood obesity exists. There is a number of proposed international body mass index (BMI)-based systems in use and national variants also exist in many countries. The absence of a universally accepted standard and confusion concerning which classification system to use on national levels complicate monitoring of the development of the obesity epidemic, stratification for selective interventions in public health, screening in clinical practice and comparisons between studies. Some proposed international classification systems have not only been recommended for global monitoring and comparisons between studies, but also for clinical and national epidemiological use in some countries. Possible discrepancies may thereby lead to inefficiencies in health care delivery and prevention programmes. The problems associated with misclassification of individuals at risk may lead to overconsumption of health care resources by lower-risk individuals and underconsumption by higher-risk individuals, which is costly both in terms of foregone health improvements and in terms of wasteful monetary usage. The aim of this paper was to review the specific problems associated with BMI as a measure of adiposity in childhood, the most commonly used classification systems for childhood obesity based on BMI, and how their performance can be evaluated.

Health consequences of obesity

The recent epidemic of childhood obesity(1) has raised concern because of the possible clinical and public health consequences.(2,)(3) However, there remains a widespread perception among health professionals that childhood obesity is a largely cosmetic problem, with minor clinical effects. No systematic review has yet focused on the diverse array of possible consequences of childhood obesity, though older non-systematic reviews are available.(4,)(5) In addition, no review to date has considered the vast body of evidence on the health impact of childhood obesity which has been published recently. The aim of the present review was therefore to provide a critically appraised, evidence based, summary of the consequences of childhood obesity in the short term (for the child) and longer term (in adulthood).

Coexistence of social inequalities in undernutrition and obesity in preschool children: population based cross sectional study

AIMS

To test for the coexistence of social inequalities in undernutrition and obesity in preschool children.

METHODS

Retrospective, cross sectional, study of routinely collected data from 74 500 children aged 39-42 months in 1998/99. Main outcome measures were weight, height, sex, and age routinely recorded by health visitors. Body mass index (BMI) standardised for age and sex, relative to UK 1990 reference data, was used to define undernutrition (BMI <2nd centile) and obesity (BMI >95th centile; BMI >98th centile). Social deprivation was assessed as Carstairs deprivation category (1 = most affluent to 7 = most deprived).

RESULTS

Both undernutrition (3.3%) and obesity (8.5% above 95th centile; 4.3% above 98th centile) significantly exceeded expected frequencies from UK 1990 reference data. Undernutrition and obesity were significantly more common in the more deprived families. Odds ratios in deprivation category 7 relative to category 1 were 1.51 (95% CI 1.22 to 1.87) for undernutrition (BMI <2nd centile) and 1.30 (95% CI 1.05 to 1.60) for obesity (BMI >98th centile). The cumulative prevalence of under and overnutrition (malnutrition) in the most deprived group was 9.5% compared to 6.9% in the least deprived group.

CONCLUSIONS

Undernutrition and obesity are significantly more common than expected in young children and strongly associated with social deprivation. Both undernutrition and obesity have adverse short and long term health effects. Public health strategies need to tackle malnutrition (both undernutrition and obesity) in children and take into consideration the association with social deprivation.

Objectively measured physical activity in a representative sample of 3- to 4-year-old children

OBJECTIVE

This study aimed to describe levels of physical activity in a representative sample of preschool children and to quantify tracking of activity over 1 year.

RESEARCH METHODS AND PROCEDURES

Physical activity (mean accelerometry counts/minute) was assessed over 3 days using the Computer Science and Applications accelerometer in 3- to 4-year-old children (n = 104; 52 boys; mean age, 3.7 +/- 0.4 years). In 60 children (30 boys), measurements were repeated 1 year later.

RESULTS

Mean total activity at baseline was 777 +/- 207 counts/minute in boys and 657 +/- 172 counts/minute for girls; this gender difference was significant (p < 0.001). In the cross-sectional analysis, total activity was significantly positively related to age (r = 0.37, p = 0.007). In the sample followed up for 1 year, mean total activity was 849 +/- 252. The longitudinal analysis confirmed that total physical activity increased over the 1-year period (paired Student's t test, p < 0.001). The tracking rank order correlation coefficient of total activity count over 1 year was r = 0.40 (p < 0.001).

DISCUSSION

This study suggests that total activity increases during the preschool period in Scottish children and that gender differences in total activity are present early in life. Tracking of total activity was only modest, but adequate assessment of tracking requires methodological research aimed at elucidating the biological meaning of accelerometer output.

Assessment of childhood obesity: national reference data or international approach?

Assessing body mass index in children requires cutoffs that are different from those for adults. The aim of this review is to summarize the evidence base, rationale, and practical issues that should inform decisions about the use of national and international reference data for assessing obesity in children. In many countries, decisions are being made without consideration of the existing evidence, and with limited understanding of the practical problems or potential harm that may arise.