The epidemiology of overweight and obesity among Australian children and adolescents, 1995-97

The obesity epidemic: prospects for prevention

Some 20-25% of UK adults are obese according to the WHO criterion (BMI >/=30 kg/m(2)). Type 2 diabetes, increasingly recognized as a major complication of overweight and obesity, is beginning to appear in UK adolescents, following the trends in the US. Epidemiological data indicate that the prevalence of overweight and obesity has doubled or tripled in the past few decades in the US, in Europe, and even in many developing countries. Thus obesity is increasingly seen as a public health problem requiring concerted action by both governmental and non-governmental organizations. A sound understanding of the root causes is crucial, if strategies for the prevention and treatment of this epidemic are to be developed. Many epidemiological studies suggest that physical activity at work, school or at leisure has declined to minimal levels, and that sedentary behaviours such as television viewing and computer games have become major pastimes. Thus energy requirements are substantially less than those for recent generations. Further, the food industry produces high-calorie foods which children and adults consume as snack meals, giving a substantial surfeit to their daily energy requirement. In children, a few school-based, preventive intervention trials have shown some promising results. Many negative trials have also been reported, and practical difficulties remain in the widespread implementation of appropriate protocols. Initiatives have been introduced by the government to increase the physical education syllabus in school to a minimum of 2 h/week, and the promotion of fruit and vegetables. Further research is required on the physiological and psychological causes of overweight and obesity in children and adults, and randomized, controlled, school and community-based trials are required to pilot preventative initiatives. Monitoring of the progress in prevention at both organizational and outcome level is required, and also of adverse outcomes such as a rise in the prevalence of eating disorders.

[Exercise. Prevention and health promotion--pathways to innovation in public health?]

Besides appropriate nutrition, adequate exercise is the universal remedy. Regular endurance training elicits positive effects in numerous organs and tissue systems in the sense of primary prevention. Nevertheless, a lack of exercise and obesity are widespread among the German population. In addition to the individual's own responsibility, measures for disease-oriented prevention as well as for preserving health should be improved based on broad social consensus. To begin with, improved research on treatment and prevention should be required. This national challenge should not only be financed by health insurance funds but also by taxes and levies (e.g., tobacco tax). Only then can the constantly spiralling costs of public health be met.

Stability of body mass index in Australian children: a prospective cohort study across the middle childhood years

OBJECTIVE

To investigate the prevalence and incidence of overweight and obesity, the frequency of overweight resolution and the influence of parental adiposity during middle childhood.

DESIGN

As part of a prospective cohort study, height and weight were measured in 1997 and 2000/2001. Children were classified as non-overweight, overweight or obese based on standard international definitions. Body mass index (BMI) was transformed into age- and gender-specific Z-scores employing the LMS method and 2000 growth chart data of the Centers for Disease Control and Prevention. Parents self-reported height and weight, and were classified as underweight, healthy weight, overweight or obese based on World Health Organization definitions.

SETTING

Primary schools in Victoria, Australia.

SUBJECTS

In total, 1438 children aged 5-10 years at baseline.

RESULTS

The prevalence of overweight and obesity increased between baseline (15.0 and 4.3%, respectively) and follow-up (19.7 and 4.8%, respectively; P<0.001 for increase in overweight and obesity combined). There were 140 incident cases of overweight (9.7% of the cohort) and 24 of obesity (1.7% of the cohort); only 3.8% of the cohort (19.8% of overweight/obese children) resolved to a healthy weight. The stability of child adiposity as measured by BMI category (84.8% remained in the same category) and BMI Z-score (r=0.84; mean change=-0.05) was extremely high. Mean change in BMI Z-score decreased with age (linear trend beta=0.03, 95% confidence interval 0.01-0.05). The influence of parental adiposity largely disappeared when children's baseline BMI was adjusted for.

CONCLUSIONS

During middle childhood, the incidence of overweight/obesity exceeds the proportion of children resolving to non-overweight. However, for most children adiposity remains stable, and stability appears to increase with age. Prevention strategies targeting children in early childhood are required.

Associations between blood pressure and overweight defined by new standards for body mass index in childhood

BACKGROUND

Using data from a longitudinal study of young Australians, we applied recent international standards for overweight and obesity to examine associations with blood pressure (BP) and to determine the prevalence and degree of tracking of overweight and obesity. We also aimed to examine socioeconomic status in relation to these variables.

METHODS

BP, height, and weight were measured at 3-year intervals from age 9 to 18, and then at 25 years of age in a Western Australian cohort. At these stages, data were available for 1,036, 1,310, 618, 615 and 600 individuals, respectively.

RESULTS

We found 10% of 9-year-old males to be overweight or obese, while among 12-year-olds, 13% were overweight or obese; at age 15, and still at age 18, overweight or obesity was registered in 17% of this population and it rose to 42% among the 25-year-old young men. The percentage of overweight or obese females at these stages was initially 8, then 12 (at age 12), 11 (at age 15), 14 (at age 18) and finally 32. Overweight or obesity tracked to young adult life in 16% of those overweight or obese at 9, 24% at 12, 34% at 15 and 35% at 18 years. Systolic BP was significantly higher in the overweight or obese except in 12-year-olds. At the age of 25 years, 53% of men had high normal BP or were hypertensive.

CONCLUSIONS

Increasing overweight or obesity in young Australians, consistent with international trends, has serious health implications. Overweight and obesity show tracking and are predictors of higher blood pressure, except in early adolescence.

Obesity and under-nutrition in a tertiary paediatric hospital

OBJECTIVE

(i) To determine the prevalence of over- and under-nutrition in both inpatients and outpatients in a tertiary paediatric hospital; (ii) to compare the prevalence of over-nutrition with that in the Australian community and (iii) to determine whether nutritional status has an impact on length of stay in hospital.

METHODS

Patients aged over 12 months were proportionately sampled from medical and surgical wards and outpatient clinics. Data were collected for 245 inpatients (54% male) and 272 outpatients (55% male). Children's height, weight and body mass index (kg/m2) were measured. Overweight, obesity and under-nutrition were defined according to international criteria. Prevalence of overweight and obesity was compared with that in the 1995 Australian National Nutrition Survey (NNS).

RESULTS

Similar proportions of inpatients and outpatients were underweight (6%) and wasted (4%). The prevalence of overweight and obesity in inpatients (22%) was similar to the NNS but was significantly higher in outpatients (32%, P < 0.0001). In a regression model to predict inpatient length of stay, nutritional status (P = 0.004) and the interaction between age and nutritional status (P = 0.009) were significant predictors. For over-nourished inpatients, length of stay increased significantly with age. For normally nourished and under-nourished inpatients, length of stay was relatively constant, regardless of age.

CONCLUSIONS

There is a high prevalence of over-nutrition in paediatric patients, and increased length of stay for older over-nourished inpatients. These issues need to be addressed in terms of opportunities for intervention and impact on hospital resources.

[Childhood and adolescent obesity in Spain. Results of the enKid study (1998-2000)]

BACKGROUND AND OBJECTIVE

Obesity is a chronic disease with a complex multifactorial nature which typically begins during childhood and adolescence. It represents one of today's most critical and escalating public health concerns for this segment of the population. The lack of obesity prevalence data at national level prompted the enKid Study (1998-2000), which was designed to evaluate the food habits and nutritional status of Spanish children and youth.

SUBJECTS AND METHOD

Cross-sectional epidemiological study of a representative sample of the Spanish population aged 2 to 24 years (n=3534). Height and weight measurements were carried out using standard procedures and equipment. Obesity and overweight were defined according to BMI values for the 97th and 85th percentiles, respectively using Spanish reference data provided by Hernández et al (1998).

RESULTS

The prevalence of obesity in Spain is 13.9%, while the combination of overweight and obesity yields a prevalence of 26.3% (with a prevalence of overweight alone of 12.4%). Obesity is more common in males (15.6%) than in females (12%), which was also true for overweight. With regard to age, a higher prevalence is found among those aged 6 to 13 years. As for the geographic area, Canary Islands and Andalusia show the highest prevalence and the northeast region the lowest. Obesity is also more prevalent among those people with the lowest socio-economic and educational levels, and in those who omitted or consumed a poor breakfast.

CONCLUSIONS

Compared to other countries, Spain shows an intermediate level of obesity in children and youth. Over the past decades, there has been an increasing trend towards overweight and obesity, which are more prevalent in males and during prepuberal ages.

Growth, behavior, and clinical findings in 27 patients with Kabuki (Niikawa-Kuroki) syndrome

This study was undertaken to document the phenotype of Kabuki (Niikawa-Kuroki) syndrome in patients from Australia and New Zealand, with particular emphasis on growth patterns, behavior, and relationship between head circumference and intellectual level. Data on 27 children and adults with Kabuki (Niikawa-Kuroki) syndrome from Australia and New Zealand were collected by questionnaire and clinical assessment. The patients ranged in age from 7 months to 36 years with a mean age of 7 years and 2 months. The mean age at diagnosis was 3(5/6) years, but in most cases, the facial phenotype was evident from infancy. The minimum birth prevalence was calculated at 1 in 86,000. Three of our patients died. Parents reported a behavior phenotype characterized by an excellent long-term memory and avoidance of eye contact. No correlation was found between head circumference and severity of intellectual disability. Eight of 14 patients over the age of 5 years were overweight or obese. Six of these eight patients had failure to thrive in infancy. One patient developed insulin-dependent diabetes mellitus in adolescence. Some individuals with Kabuki (Niikawa-Kuroki) syndrome show a characteristic growth profile with failure to thrive in infancy progressing to obesity or overweight in middle childhood or adolescence. A behavior phenotype was noted which requires further investigation. Head size is not a predictor of degree of intellectual disability.

Social, cultural and environmental influences on child activity and eating in Australian migrant communities

AIM

This study set out to examine the socio-cultural, familial and environmental factors influencing health, eating habits and patterns of physical activity contributing to child and adolescent overweight and obesity.

METHODS

Semi-structured, community-based interviews were conducted with contrasting key informant three-generation families; and generation by generation focus groups of grandparents, parents and children from four cultural communities in the state of Victoria, Australia. Purposive sampling occurred from Turkish, Greek, Indian and Chinese communities that have migrated to Australia within the last three generations (n = 160, eight families, 47 children aged 5-15 years, 29 parents, 42 grandparents).

RESULTS

Evidence of two-way influences on eating and physical activity across three generations was evident, with children reporting the greatest cross-cultural diversity. A range of dietary restrictions was reported across all cultural groups. Efforts to foster healthy eating and lifestyle patterns within communities were evident. Parents, as a generation in particular, felt the need for more access to education and support regarding healthy limits for pre-puberty and puberty stages.

CONCLUSION

There is a dynamic influence of culture on many aspects of family lifestyle across three generations. To achieve successful intervention design, childhood obesity researchers need to collaborate with diverse groups and communities. Considering the role and influence of extended family, a multigenerational, whole-of-community approach beyond that of parent and child populations ought to be considered.

Epidemiology of overweight and obesity among school children and adolescents in three provinces of central Italy, 1993-2001: study of potential influencing variables

OBJECTIVE

The prevalence of overweight and obesity was estimated among the school children and adolescents of three provinces of central Italy, and the role of several possible influencing factors was analysed.

DESIGN, SUBJECTS AND MEASUREMENTS

Body mass index (BMI) was measured in 44 231 subjects, age 3-17.5 y, and a household questionnaire was filled out by the parents of 12 143 subjects to collect the following data: subjects, only child or firstborn status, prematurity, birth weight, type of feeding until the fifth month, menarche status in girls; parents, age at the time of the subject's birth; BMI (mean of the two parents) at the time the subject was measured, mother's age of menarche, socioeconomic status. BMI was measured in a subgroup of 10 795 subjects 1 y later to study the yearly sex- and age-related variations from the categories of normal weight to overweight or obesity and vice versa. All females aged 11-14 y were asked if they had their menarche.

RESULTS

Striking differences in the proportions of overweight and obesity resulted from the use of two different criteria for defining cutoff points. The overall prevalence of overweight was 13.2 and 20.7% in males, and 13.7 and 18.6% in females, and the overall prevalence of obesity varied between 24.2 and 6.3% in males, and between 22.9 and 6.1% in females, respectively. Parents' BMI, birth weight, firstborn status and post-menarche status in girls showed a significant association with overweight and/or obesity in logistic regression models.

CONCLUSIONS

A large prevalence of overweight and obesity was observed in school subjects from three provinces of central Italy. From the comparisons of the prevalence rate, the new internationally agreed criteria seem more appropriate for epidemiological studies in this population.

SPONSOR

University of Perugia, Region of Umbria, Commune of Perugia.

Activity levels and body mass index of children in the United States, Sweden, and Australia

PURPOSE

Assess the physical activity and body mass index (BMI) levels of children in the United States, Sweden, and Australia.

METHODS

A total of 1954 children, 6-12 yr old (711 American, 563 Australian, and 680 Swedish) wore sealed pedometers for four consecutive days. Height and weight measures were obtained.

RESULTS

Descriptive data for step counts and BMI by sex, age, and country were calculated to determine activity levels and BMI. Three-way multivariate ANOVA for step counts and BMI between countries at each age and sex found that, in general, the Swedish children were significantly more active than the Australian and American children, and the American children were significantly heavier than the Australian and Swedish children. For boys, the mean step counts ranged from 15673 to 18346 for Sweden, 13864 to 15023 for Australia, and 12554 to 13872 for America. For girls, the mean step counts ranged from 12041 to 14825 for Sweden, 11221 to 12322 for Australia, and 10661 to 11383 for America. The activity curve is somewhat level during the preadolescent years. The rate of increase in BMI with age is much greater in the American children than in the Swedish or Australian children. The percent of American, Swedish, and Australian boys classified as overweight/obese was 33.5, 16.6, and 15.8, respectively. The percent of American, Swedish, and Australian girls classified as overweight/obese was 35.6, 16.8, and 14.4, respectively. Correlation analysis found few significant negative relationships between step counts and BMI.

CONCLUSIONS

American children tend to be the least active and heaviest with the greatest rate of increase in BMI. The Swedish children are the most active group followed by Australia. Swedish and Australian children maintain lower BMI throughout their prepubescent years than do the American children who have a greater percentage who are classified as overweight.

Physical activity in overweight and nonoverweight preschool children

OBJECTIVE

To compare the physical activity levels of overweight and non overweight 3- to 5-y-old children while attending preschool. A secondary aim was to evaluate weight-related differences in hypothesized parental determinants of child physical activity behavior.

DESIGN

Cross-sectional study.

SUBJECTS

A total of 245, 3- to 5-y-olds (127 girls, 118 boys) and their parent(s) (242 mothers, 173 fathers) recruited from nine preschools. Overweight status determined using the age- and sex-specific 85th percentile for body mass index (BMI) from CDC Growth Charts.

MEASUREMENTS

Physical activity during the preschool day was assessed on multiple days via two independent objective measures-direct observation using the observation system for recording activity in preschools (OSRAP) and real-time accelerometry using the MTI/CSA 7164 accelerometer. Parents completed a take-home survey assessing sociodemographic information, parental height and weight, modeling of physical activity, support for physical activity, active toys and sporting equipment at home, child's television watching, frequency of park visitation, and perceptions of child competence.

RESULTS

Overweight boys were significantly less active than their nonoverweight peers during the preschool day. No significant differences were observed in girls. Despite a strong association between childhood overweight status and parental obesity, no significant differences were observed for the hypothesized parental influences on physical activity behavior.

CONCLUSIONS

Our results suggest that a significant proportion of overweight children may be at increased risk for further gains in adiposity because of low levels of physical activity during the preschool day.

Association between overweight or obesity and household income and parental body mass index in Australian youth: analysis of the Australian National Nutrition Survey, 1995

This study is a secondary data analysis based on the 1995 Australian National Nutrition Survey (NNS). A random subsample of 1581 school children aged 7-15 years old from the NNS was studied. The results show the prevalence of overweight, obesity and combined overweight and obesity was 10.6-20.9%, 3.7-7.2% and 15.6-25.7%, respectively. The odds ratio of overweight or obese boys with highest household income was significantly smaller than those with the lowest household income. The proportion of combined overweight and obesity in children whose parents were overweight or obese was significantly greater compared with those whose parents were not. The trend of increasing prevalence of overweight or obesity among children with increasing parental body mass index (BMI) was significant after adjusting for age except the trend of father's BMI for boys. This study provided baseline data on the recent prevalence of overweight or obesity of Australian school children using new international absolute BMI cut-off points. It indicated that young school girls (7-9 years) were more likely to be overweight or obese compared with boys, the prevalence rates of overweight or obesity in older boys (13-15 year) was significantly greater than in other age groups while in girls it was the opposite. The boys with lowest household income ($0-17 500) were more likely to be overweight or obese compared with those with the highest household income (greater than $67 500). Having parents especially mothers who were overweight or obese may increase the risk of children being overweight or obese.

Interventions for treating obesity in children

BACKGROUND

The prevalence of overweight and obesity is increasing in child populations throughout the world. Obesity in children has significant short and long term health consequences.

OBJECTIVES

To assess the effects of a range of lifestyle interventions designed to treat obesity in childhood.

SEARCH STRATEGY

We searched CCTR, MEDLINE, EMBASE, CINAHL, PsychLIT, Science Citation Index, Social Science Citation Index. Each database was searched from 1985 to July 2001. We also contacted experts in child obesity treatment.

SELECTION CRITERIA

We selected randomised controlled trials of lifestyle interventions for treating obesity in children with a minimum of six months duration. Examples of lifestyle interventions include dietary, physical activity and/or behavioural therapy interventions, with or without the support of associated family members. Interventions from any setting and delivered by any professional were considered. However, interventions that specifically dealt with the treatment of eating disorders were excluded.

DATA COLLECTION AND ANALYSIS

Two of our research team independently assessed trial quality and extracted data. Authors of the included studies were contacted for additional information where this was appropriate.

MAIN RESULTS

We included 18 randomised controlled trials with 975 participants. Many studies were run from a specialist obesity clinic within a hospital setting. Five studies (n=245 participants) investigated changes in physical activity and sedentary behaviour. Two studies (n=107 participants) compared problem-solving with usual care or behavioural therapy. Nine studies (n=399 participants) compared behavioural therapy at varying degrees of family involvement with no treatment or usual care or mastery criteria and contingent reinforcement. Two studies (n=224 participants) compared cognitive behavioural therapy with relaxation.Most of the studies included in this review were too small to have the power to detect the effects of the treatment. We did not conduct a meta-analysis since so few of the trials included the same comparisons and outcomes. Therefore, we synthesised the results in a narrative format.

REVIEWER'S CONCLUSIONS

Although 18 research studies were found, most of these were very small studies drawn from homogenous, motivated groups in hospital settings and so generalisable evidence from them is limited. In conclusion, there is a limited amount of quality data on the components of programs to treat childhood obesity that favour one program over another. Further research that considers psychosocial determinants for behaviour change, strategies to improve clinician-family interaction, and cost-effective programs for primary and community care is required. We conclude that no direct conclusions can be drawn from this review with confidence.

Change in the prevalence of overweight and obesity among young Australians, 1969-1997

BACKGROUND

Effective public policy requires information on the prevalence of overweight and obesity.

OBJECTIVE

We determined changes in the population prevalence of overweight and obesity among young Australians (aged 7-15 y) from 1969 to 1985 to 1997.

DESIGN

Data from 5 independent population surveys were analyzed: the Australian Youth Fitness Survey, 1969; the Australian Health and Fitness Survey, 1985; the South Australian Schools Fitness and Physical Activity Survey, 1997; the New South Wales Schools Fitness and Physical Activity Survey, 1997; and the Health of Young Victorians Study, 1997. Measured body mass index was used as the index of adiposity, and recently published body mass index cutoff values were used to categorize each subject as nonoverweight, overweight, obese, or either overweight or obese.

RESULTS

For 1985-1997, the population prevalence of overweight increased by 60-70%, obesity increased 2-4-fold, and the combined overweight and obesity categories doubled. The findings were consistent across data sets and between the sexes. For 1969-1985, there was no change in the prevalence of overweight or obesity among girls, but among boys the prevalence of overweight increased by 35%, the prevalence of obesity trebled, and the prevalence of overweight and obesity combined increased by 60%.

CONCLUSIONS

The data show that in 1985-1997, the prevalence of overweight and obesity combined doubled and that of obesity trebled among young Australians, but the increase over the previous 16 y was far smaller. These results should increase our sense of urgency in identifying and implementing effective responses to this major threat to public health.

Obesity: epidemiology and possible prevention

Obesity can be defined as the excessive accumulation of fat in adipose tissue, to the extent that health may be impaired. The most widely used measures of total and abdominal adiposity are the body mass index and waist circumference. Obesity is now a global public health problem, with about 315 million people world-wide estimated to fall into the WHO-defined obesity categories with a body mass index (BMI) of 30 or above. The primary causes of the rapid global rise in obesity rates lie in the profound environmental and societal changes now affecting large parts of the world and creating societies in which physical activity is low and the availability of high-fat, energy-dense foods has increased. Strategies aimed at preventing weight gain and obesity have not been successful to date but are likely to be more cost effective, and to have a greater positive impact on long-term control of body weight than treating obesity once it has developed.

Parent-reported health status of overweight and obese Australian primary school children: a cross-sectional population survey

INTRODUCTION

Childhood overweight/obesity is associated with poor physical and psychosocial health in clinical samples. However, there is little information on the health status of overweight and obese children in the community, who now represent a large proportion of the child population. We examined parent-reported child health and well-being and parent concern about child weight by body mass index (BMI) category in a population sample of primary school children.

DESIGN

A stratified two-stage random cluster sample of 24 primary schools representative of the state of Victoria, Australia.

MEASURES

BMI (weight/height(2)) transformed to normalised Z-scores using the 1990 UK Growth Reference; the Child Health Questionnaire (CHQ), a 13-scale 50-item parent-completed measure of health and well-being; parent self-reported height and weight; parent concern about child's weight.

RESULTS

Data were available for 2863 children aged 5-13 y (50.5% male), of whom 17% were overweight and 5.7% obese. Using logistic regression analyses with 'normal weight' as the referent category, obese boys were at greater risk of poor health (ie <15th centile) on seven of the 12 CHQ scales: Physical Functioning (odds ratio (OR) 2.8), Bodily Pain (OR 1.8), General Health (OR 3.5), Mental Health (OR 2.8), Self Esteem (OR 1.8), Parent Impact-Emotional (OR 1.7) and Parent Impact-Time (OR 1.9). Obese girls were at greater risk of poor health on only two scales: General Health (OR 2.1) and Self Esteem (OR 1.8). Forty-two percent of parents with obese children and 81% with overweight children did not report concern about their child's weight. Parents were more likely to report concern if the child was obese (OR 21.3), overweight (OR 3.5) or underweight (OR 5.4) than normal weight (P<0.05). Concern was not related to child gender, parental BMI or parental education after controlling for child BMI. Perceived health and well-being of overweight/obese children varied little by weight category of the reporting parent (overweight vs non-overweight).

CONCLUSIONS

Parents were more likely to report poorer health and well-being for overweight and obese children (particularly obese boys). Parental concern about their child's weight was strongly associated with their child's actual BMI. Despite this, most parents of overweight and obese children did not report poor health or well-being, and a high proportion did not report concern. This has implications for the early identification of such children and the success of prevention and intervention efforts. DOI:10.1038/sj/ijo/0801974

Interventions for preventing obesity in children

BACKGROUND

The prevalence of obesity and overweight is increasing in both adult and child populations throughout the world. Obesity in children impacts on their health in both the short and longer term, and obesity prevention is an international public health priority. However, the efficacy of prevention strategies is poorly understood.

OBJECTIVES

To assess the effectiveness of educational, health promotion and/or psychological/family/behavioural therapy/counselling/management interventions that focussed on diet, physical activity and/or lifestyle and social support, and were designed to prevent obesity in childhood.

SEARCH STRATEGY

The following databases were searched: MEDLINE, Psyclit, EMBASE, Science Citation Index, Social Science Citation Index, CINAHL, Cochrane Controlled Trials Register (CCTR) and the Cochrane Heart Group's specialised register from 1985 to July 2001. Non English language papers were included. Experts were contacted to seek additional references or unpublished studies.

SELECTION CRITERIA

RCTs and non-randomised trials with concurrent control group that observed participants for a minimum of three months were included

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Ten studies were included; seven were long-term (children observed for at least one year), three were shorter term (at least 3 months). Eight were school/nursery-based interventions, one was a community-based intervention targeting low-income African-American families, and one was a family-based intervention that targeted non-obese children of obese parents. The studies included were diverse in terms of study design and quality, target population, theoretical underpinning of intervention approach, and outcome measures, so it was not possible to combine study findings using statistical methods. Three of the four long-term studies that combined dietary education and physical activity interventions resulted in no difference in overweight, whereas one study reported an improvement in favour of the intervention group. In two studies of dietary education alone, a multimedia action strategy appeared to be effective but other strategies did not. The one long term study that only focussed on physical activity resulted in a slightly greater reduction in overweight in favour of the intervention group, as did two short term studies of physical activity.

REVIEWER'S CONCLUSIONS

There is limited high quality data on the effectiveness of obesity prevention programs and no generalisable conclusions can be drawn. However, concentration on strategies that encourage reduction in sedentary behaviours and increase in physical activity may be fruitful. The need for well-designed studies that examine a range of interventions remains a priority, although a number of important studies are underway.

Interventions for preventing obesity in childhood. A systematic review

BACKGROUND

The prevalence of obesity and overweight is increasing worldwide. Obesity in children impacts on their health in both short- and long-term. Obesity prevention strategies are poorly understood.

OBJECTIVE

To assess the effectiveness of interventions designed to prevent obesity in childhood.

SEARCH STRATEGY

Electronic databases were searched from January 1985 to October 1999.

SELECTION CRITERIA

Data from randomized control trials and non-randomized trials with concurrent control group were included. A priori, studies with follow up of 1 year minimum were selected however, this was subsequently amended to include studies with a minimum follow up of three months.

DATA COLLECTION & ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Seven studies were included, three long-term (> 1 years) and four short-term (> 3 months and < 1 years). The studies included were diverse in terms of study design and quality, target population, theoretical underpinning of intervention approach, and outcome measures. As such, it was not appropriate to combine study findings using statistical methods.

CONCLUSIONS

Two of the long-term studies (one focused on dietary education and physical activity vs. control, and the other only on dietary education vs. control), resulted in a reduction in the prevalence on obesity, but the third, which focused on dietary education and physical activity, found no effect. Of the four short-term studies, three focused simply on physical activity/reduction of sedentary behavious vs. control. Two of these studies resulted in a reduction in the prevalence of obesity in intervention groups compared with control groups, and another study found a non-significant reduction. The fourth study focused on dietary education and physical activity, and did not find an effect on obesity, but did report a reduction in fat intake. Overall, the findings of the review suggest that currently there is limited quality data on the effectiveness of obesity prevention programmes and as such no generalizable conclusions can be drawn. The need for well-designed studies that examine a range of interventions remains a priority.