Effects of the Healthy Start randomized intervention trial on physical activity among normal weight preschool children predisposed to overweight and obesity

Scoping review showed that obesity prevention in Nordic countries had limited effects on children from birth to 7 years of age

AIM

The aim of this scoping review was to map and summarise clinical trials that attempted to prevent obesity in children from birth to 7 years of age in any of the Nordic countries.

METHODS

PubMed, CINAHL Plus and clinicaltrials.gov were searched for peer-reviewed papers and registered trials published in English or Swedish. The overall search period was from 1 January 2002 to 13 December 2022. We included randomised and non-randomised trials initiated from birth to 7 years of age that aimed to prevent obesity in Denmark, Finland, Iceland, Norway and Sweden.

RESULTS

The search resulted in 414 papers and 14 were included. Despite having diverse settings and designs, none of them reported consistently favourable results for anthropometric outcomes, apart from beneficial trends in subgroups with a high body mass index at baseline. Most studies reported temporarily improved dietary patterns.

CONCLUSION

There is a gap in the current research about how to best prevent obesity in children. We suggest that researchers should focus on risk groups and that interventions that last a number of years are needed.

A literature review of evidence for primary prevention of overweight and obesity in healthy weight children and adolescents: A report produced by a working group of the Danish Council on Health and Disease Prevention

Primary prevention targets development of overweight in individuals with healthy weight and is a great challenge. This paper summarizes the main findings of a working group of the Danish Council on Health and Disease Prevention that reviewed the literature on primary prevention of overweight and obesity among children and adolescents. The results were presented in a Danish report, in which a 2019 Cochrane review on childhood obesity prevention was complemented by searches in PubMed to include all relevant subsequent studies published from January 2018 until March 2020. In this paper, the review was updated until June 2023. Numerous childhood overweight prevention interventions have been developed during the past decades, primarily targeting diet and/or physical activity. Several of these interventions showed positive effects on diet and physical activity level but did not show effects on risk of developing overweight. The evidence foundation is inconsistent as four out of five interventions did not show positive effects. Previously observed intervention effects may not reflect excessive weight gain prevention among children with healthy weight but rather bodyweight reduction among those with overweight or obesity. We do not have sufficient knowledge about how to prevent children with healthy weight from developing overweight, and creative solutions are urgently needed.

The Effectiveness of a Healthy Lifestyle in Obese Pediatric Patients: A Systematic Review and Meta-Analysis

Child and adolescent obesity represents a significant and escalating health concern in the United States. Notably, Hispanic adolescents face a higher prevalence of obesity and an increased risk of cardiovascular disease compared to their peers from different racial and ethnic backgrounds. This was obtained through systematic investigations in which different approaches were used. Therefore, obesity interventions of long duration, at least one year, and with a beginning phase intensive enough to produce significant early weight loss may be needed for adolescents with obesity. Surprisingly, despite this elevated risk, there is a glaring underrepresentation of Hispanics in obesity intervention studies aimed at youth. It is therefore imperative to develop interventions tailored specifically to overweight adolescents, with a particular focus on the Hispanic population. While researchers have addressed numerous interventions targeting adolescent obesity, many of these initiatives have demonstrated limited treatment efficacy, failed to achieve all desired treatment objectives, experienced high attrition rates, and encountered waning participant engagement. To evaluate the impact of adopting a healthy lifestyle among pediatric patients struggling with obesity, we undertook a comprehensive systematic review of the literature, and with the information obtained from the articles chosen, we will undergo a meta-analysis. Our review encompassed a 10-year span of published literature, drawing upon online databases including the Cochrane Library, PubMed, Web of Science, PubMed Central, and Google Scholar. Our review exclusively considered randomized controlled trials that focused on the effectiveness of various lifestyle modifications for pediatric patients grappling with obesity. We synthesized the pooled incidence, risk ratio, and associated 95% confidence intervals to gauge the efficacy of these interventions, employing the fixed-effect model to account for potential between-study variations rather than the random-effect model. After the calculation of each one of the studies selected, we could conclude that it gave good outcomes after the modification of lifestyle in these patients, giving a statistical significance and p-value in our three representative figures of <0.001.

Paper II: thematic framework analysis of registry-based randomized controlled trials provided insights for designing trial ready registries

OBJECTIVES

Registry-based randomized controlled trials (RRCTs) are increasingly used, promising to address challenges associated with traditional randomized controlled trials. We identified strengths and limitations reported in planned and completed RRCTs to inform future RRCTs.

STUDY DESIGN AND SETTING

We conducted an environmental scan of literature discussing conceptual or methodological strengths and limitations of using registries for trial design and conduct (n = 12), followed by an analysis of RRCT protocols (n = 13) and reports (n = 77) identified from a scoping review. Using framework analysis, we developed and refined a conceptual framework of RRCT-specific strengths and limitations. We mapped and interpreted strengths and limitations discussed by authors of RRCT articles using framework codes and quantified the frequencies at which these were mentioned.

RESULTS

Our conceptual framework identified six main RRCT strengths and four main RRCT limitations. Considering implications for RRCT conduct and design, we formulated ten recommendations for registry designers, administrators, and trialists planning future RRCTs.

CONCLUSION

Consideration and application of empirically underpinned recommendations for future registry design and trial conduct may help trialists utilize registries and RRCTs to their full potential.

Determinants of Outdoor Time in Children and Youth: A Systematic Review of Longitudinal and Intervention Studies

Spending more time outdoors can improve children's social and cognitive development, physical activity, and vision. Our systematic review summarized the determinants of outdoor time (OT) based on the social-ecological model. We searched nine databases: MEDLINE, APA PsycINFO, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, SPORTDiscus, ERIC, SocINDEX, and ProQuest Dissertations and Theses. To be included, studies needed to be quantitative and longitudinal, include ≥1 potential determinant of OT among 0- to 17-year-olds, and be published in English, French, Japanese, or Spanish. We extracted the authors, publication year, country, design, sample size, OT measures, follow-up period, potential determinants, main results, and potential moderators or mediators. Fifty-five studies examining 119 potential determinants met the inclusion criteria. OT was consistently higher in warmer seasons and among participants reporting more OT at baseline. All three interventions that included both parent sessions and additional resources to promote OT (e.g., specific advice and community guides) were effective. COVID-19 restrictions and sun safety interventions discouraging midday outdoor activities led to less OT. The quality of evidence was rated as weak for 46 studies. Most potential determinants were examined in ≤3 studies; thus, more longitudinal studies are needed to enable stronger conclusions about the consistency of evidence and meta-analyses.

Effects of the healthy start randomized intervention on psychological stress and sleep habits among obesity-susceptible healthy weight children and their parents

Poor sleep and psychological stress are obesity determinants that are rarely included in obesity prevention programs. The aim was to report the effects of the Healthy Start randomized intervention on the secondary outcomes psychological stress and sleep duration and onset latency. Data was obtained from the Healthy Start randomized intervention conducted in 2009–2012 among Danish healthy weight children aged 2–6 years, who had either a high birth weight (>4,000 g), high maternal pre-pregnancy body mass index (>28 kg/m2), or low maternal educational level (≤10 years of schooling) and their parents. The intervention was designed to deliver improvements in diet and physical activity habits, optimization of sleep habits, and reduction of psychological family stress. The average intervention period was 15 months. Children with information on a 7-day sleep record, sleep onset latency, Strengths and Difficulties Questionnaire (SDQ), and a modified version of Parenting Stress Index (PSI) were included. The effects of the intervention on sleep habits, PSI scores, SDQ Total Difficulties (SDQ-TD) and Pro-social Behavior scores, and 95% Confidence Intervals (95% CI) were analyzed using linear regression intention-to-treat (n = 543 (intervention group n = 271, control group n = 272)) analyses. No statistically significant effects on sleep duration, sleep onset latency, PSI score, or SDQ Pro-social Behavior score were observed. Values both before and after the intervention were within the normal range both for children in the intervention and children in the control group. Mean change in SDQ-TD was 0.09 points (95% CI -0.57;0.59) in the intervention group, and -0.69 points (95% CI -1.16; -0.23) in the control group (p = 0.06). In conclusion, there were no intervention effects in relation to sleep duration, sleep onset latency, PSI score, or SDQ Pro-social behavior. There was an indication that children in the intervention group had slightly more behavioral problems than the control group after the intervention, but values were within normal range both before and after the intervention, and the difference is not considered to be clinically meaningful.

A Systematic Review of the Relationships Between Physical Activity and Sleep in Early Childhood

The aim of this systematic review was to examine the associations between physical activity and sleep in children aged less than 6 years. Articles were included if participants were primarily aged less than 6 years and study designs were observational or experimental. Study characteristics were extracted, and the Grading Recommendations Assessment, Development and Evaluation framework was used to assess study quality. Thirty-six studies (16 sleep, 16 physical activity, and three fitness outcomes) from 18 countries reported in 29 articles were included. The majority of sleep and physical activity outcome studies reported mixed effects with very low to low quality of evidence. Fitness outcome studies were limited, and therefore, evidence was insufficient. The high prevalence of mixed and null results could be related to study limitations. Importantly, this review points to the critical need for higher quality studies of sleep and physical activity in young children, which would support health recommendations and intervention strategies for healthier child development.

Identifying effective intervention strategies to reduce children's screen time: a systematic review and meta-analysis

BACKGROUND

Excessive screen time ([Formula: see text] 2 h per day) is associated with childhood overweight and obesity, physical inactivity, increased sedentary time, unfavorable dietary behaviors, and disrupted sleep. Previous reviews suggest intervening on screen time is associated with reductions in screen time and improvements in other obesogenic behaviors. However, it is unclear what study characteristics and behavior change techniques are potential mechanisms underlying the effectiveness of behavioral interventions. The purpose of this meta-analysis was to identify the behavior change techniques and study characteristics associated with effectiveness in behavioral interventions to reduce children's (0-18 years) screen time.

METHODS

A literature search of four databases (Ebscohost, Web of Science, EMBASE, and PubMed) was executed between January and February 2020 and updated during July 2021. Behavioral interventions targeting reductions in children's (0-18 years) screen time were included. Information on study characteristics (e.g., sample size, duration) and behavior change techniques (e.g., information, goal-setting) were extracted. Data on randomization, allocation concealment, and blinding was extracted and used to assess risk of bias. Meta-regressions were used to explore whether intervention effectiveness was associated with the presence of behavior change techniques and study characteristics.

RESULTS

The search identified 15,529 articles, of which 10,714 were screened for relevancy and 680 were retained for full-text screening. Of these, 204 studies provided quantitative data in the meta-analysis. The overall summary of random effects showed a small, beneficial impact of screen time interventions compared to controls (SDM = 0.116, 95CI 0.08 to 0.15). Inclusion of the Goals, Feedback, and Planning behavioral techniques were associated with a positive impact on intervention effectiveness (SDM = 0.145, 95CI 0.11 to 0.18). Interventions with smaller sample sizes (n < 95) delivered over short durations (< 52 weeks) were associated with larger effects compared to studies with larger sample sizes delivered over longer durations. In the presence of the Goals, Feedback, and Planning behavioral techniques, intervention effectiveness diminished as sample size increased.

CONCLUSIONS

Both intervention content and context are important to consider when designing interventions to reduce children's screen time. As interventions are scaled, determining the active ingredients to optimize interventions along the translational continuum will be crucial to maximize reductions in children's screen time.

Measurement of screen time among young children aged 0-6 years: A systematic review

The impact of screen-based devices on children's health and development cannot be properly understood without valid and reliable tools that measure screen time within the evolving digital landscape. This review aimed to summarize characteristics of measurement tools used to assess screen time in young children; evaluate reporting of psychometric properties; and examine time trends related to measurement and reporting of screen time. A systematic review of articles published in English across three databases from January 2009 to April 2020 was undertaken using PROSPERO protocol (registration: CRD42019132599) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Included articles measured screen time as outcome, exposure, or confounder in children 0-6 years. The search identified 35,868 records, 1035 full-text articles were screened for eligibility, and 622 met inclusion criteria. Most measures (60%) consisted of one to three items and assessed duration of screen time on a usual day. Few measures assessed content (11%) or coviewing (7%). Only 40% of articles provided a citation for the measure, and only 69 (11%) reported psychometric properties-reliability n = 58, validity n = 19, reliability and validity n = 8. Between 2009 and 2019, the number of published articles increased from 28 to 71. From 2015, there was a notable increase in the proportion of articles published each year that assessed exposure to mobile devices in addition to television. The increasing number of published articles reflects increasing interest in screen time exposure among young children. Measures of screen time have generally evolved to reflect children's contemporary digital landscape; however, the psychometric properties of measurement tools are rarely reported. There is a need for improved measures and reporting to capture the complexity of children's screen time exposures.

Primary prevention of fat and weight gain among obesity susceptible healthy weight preschool children. Main results from the "Healthy Start" randomized controlled intervention

BACKGROUND

A vital public health challenge lies in understanding the primary drivers behind excessive weight gain among healthy weight individuals.

OBJECTIVES

To examine if excessive weight and fat gain can be prevented among healthy weight, obesity susceptible children aged 2 to 6 years.

METHODS

Eligible children were identified based on information on either a high birth weight, maternal pre-pregnancy obesity or maternal low educational level from national registries, and randomized into an intervention group, a control group and a shadow control group. All children with overweight at baseline were excluded from subsequent analysis (n = 196), while healthy weight children were included (n = 926). The intervention was designed to deliver improvements in diet and physical activity habits, optimization of sleep quantity and quality, and reduction of family stress. The average intervention period was 1.3 years.

RESULTS

Intention-to-treat analyses indicated a lower gain in percentage fat mass and a higher gain in fat-free mass in the intervention group compared with the control group. However, the results should be interpreted with caution, as they were clinically small and borderline significant, only.

CONCLUSION

This primary prevention intervention among young healthy weight children with susceptibility to future obesity had clinically small effects on growth and body composition. More interventions, conducting primary obesity prevention, are urgently needed.

Encouraging "Active Learning": Assessing Implementation of Head Start's Physical Activity Requirements Within the Teaching and Learning Environment

BACKGROUND

Head Start serves over 1 million diverse low-income preschool children and is an ideal setting for developing and implementing obesity prevention efforts, which is expected to have positive impacts on behavior as youth age. This study examined how regional- and state-level Head Start offices have supported implementation of the recently updated physical activity (PA) requirement within the teaching and learning environment Head Start Program Performance Standard (1302.31).

METHODS

Key informant telephone interviews were conducted with 8 regional- and 36 state-level Head Start representatives. Interviews were recorded and professionally transcribed. Data were coded and analyzed using constant comparative methods in ATLAS.ti (version 8). Audit trails were maintained, and disagreements in codes were discussed and resolved among coders.

RESULTS

The following 3 overarching themes emerged: communication, resources and technical assistance, and challenges. Results showed variation in respondent knowledge regarding the Standards. Although regional contacts provide technical assistance, state-level contacts have many information sharing strategies for programs. Implementation challenges included the need for frequent professional development opportunities given staff turnover and low PA competency, and additional PA curricula.

CONCLUSION

Findings can help identify existing or potential strategies that could be adopted more widely or developed to assist Head Start programs incorporate PA into daily activities.

Associations between Public Transport Accessibility around Homes and Schools and Walking and Cycling among Adolescents

Good public transport accessibility is associated with active travel, but this is under-researched among adolescents. We tested associations between public transport accessibility and active travel among school-going adolescents (12-18 years; n = 1329) from Melbourne, Australia analysing Victorian Integrated Survey of Travel and Activity data. Outcomes included main mode of transport to school and accumulating ≥20 min of active travel over the day. Low and high compared to no public transport accessibility around homes were associated with higher odds of public transport use (low (odds ratio (OR): 1.94 95% confidence interval (CI): 1.28, 2.94) high (OR: 2.86 95% CI: 1.80, 4.53)). Low and high public transport accessibility around homes were also associated with higher prevalence of achieving ≥20 min of active travel (low (prevalence ratio (PR): 1.14 95% CI: 0.97, 1.34) high (PR: 1.31 95% CI: 1.11, 1.54)) compared to none. Public transport accessibility around schools was associated with public transport use (low (OR: 2.13 95% CI: 1.40, 3.24) high (OR: 5.07 95% CI: 3.35, 7.67)) and achieving ≥20 min of active travel (low (PR: 1.18 95% CI: 1.00, 1.38) high (PR: 1.64 95% CI: 1.41, 1.90)). Positive associations were confirmed between public transport accessibility and both outcomes of active travel.

Comparative analysis of gross motor coordination between overweight/obese and eutrophic children

Abstract Introduction: Overweight and obese children may have lower motor coordination score than normal-weight children. Objective: To compare gross motor coordination between overweight/obese and normal-weight children and investigate the associated factors with the motor coordination scores. Method: This cross-sectional study involved 169 children of both genders, aged 6-9 years. Children with malformations, bone, muscle, and joint or neurological disorders, and BMI z < -2 were excluded. Gross motor coordination was assessed by the “Körperkoordinationstest für Kinder” (KTK). The associated factors with the motor coordination scores were analyzed by linear regression. Results: The mean scores for balancing backwards (84.2 ± 13.2 vs. 91.0 ± 15.0), hopping over on one foot (127.9 ± 10.1 vs. 132.3 ± 12.1), shifting platforms sidewise (123.5 ± 23.4 vs. 129.8 ± 14.9), as well as the overall motor scores (112.5 ± 14.8 vs. 118.8 ± 11.6) were significantly lower (p < 0.05) in overweight/obese children when compared to normal-weight children. The percentage of poor motor scores (< 85) in balancing backwards was higher in overweight/obese children (60.4% vs. 36.4%, p = 0.004) and was similar for jumping sideways (18.8% vs. 9.9%, p = 0.116), as well as for shifting platforms sidewise (6.3% vs. 0.8%, p = 0.070). By multiple linear regression analysis, the variables overweight/obesity and sports practice for less than 2 times/week decreased significantly (p < 0.05) the motor coordination score by -18.7 and -15.6 points, respectively. Conclusion: The overweight/obese children scored lower in the motor coordination tests compared to the normal-weight children. Overweight/obesity and low frequency of physical activity were associated with lower scores of gross motor coordination.

Home-Based Exergaming on Preschoolers' Energy Expenditure, Cardiovascular Fitness, Body Mass Index and Cognitive Flexibility: A Randomized Controlled Trial

PURPOSE

The effects of exergaming-based physical activity (PA) interventions on preschoolers' health outcomes and cognition remain largely unexplored. Therefore, we conducted a randomized controlled trial to discern the effectiveness of a home-based educational exergaming intervention on preschoolers' energy expenditure, fitness, body mass index, and cognition.

METHODS

Participants were 32 preschoolers (16 girls; 59.4% Asian; M_age = 4.72, SD = ±0.73) recruited from the Twin Cities area in Minnesota. During baseline testing, we measured preschooler's daily energy expenditure (EE), cardiovascular fitness, body mass index, and cognitive flexibility using validated instruments. Participants were then randomly assigned to one of two conditions: (1) the exergaming intervention condition; or (2) control condition. The intervention program requested children participate in home-based educational exergaming using the LeapTV gaming console for at least 30 min/session 5 times/week. The control condition asked children to maintain regular PA patterns without any exergaming gameplay. Each condition lasted 12 weeks. We conducted identical outcome assessments for all children at baseline and post-intervention.

RESULTS

Analysis of covariance with repeated measures yielded significant time x group interaction effects for cognitive flexibility, Wilks' Lambda = 0.81, F(1, 29) = 6.98, p = 0.01, η² = 0.19, suggesting children in the exergaming group demonstrated significantly greater increases in cognitive flexibility as compared to those in the control group over time. There were no significant differences for time x group changes between the two groups for EE, Wilks' Lambda = 0.92, F(1, 29) = 2.29, p = 0.14, η² = 0.08; cardiovascular fitness, Wilks' Lambda = 0.96, F(1, 29) = 1.07, p = 0.31, η² = 0.04; and BMI, Wilks' Lambda = 0.99, F(1, 29) = 0.05, p = 0.82, η² = 0.01. However, our data did suggest a marginal effect of time for EE, Wilks' Lambda = 0.89, F(1, 29) = 3.26, p = 0.08, η² = 0.08, indicating that children's daily EE increased from baseline to post-intervention.

CONCLUSIONS

Home-based educational exergaming may positively impact cognitive flexibility in preschoolers. Studies with larger sample sizes in multiple geographic locations are needed, with our study suggesting a longer intervention period might also be warranted.

Comparison of cardiorespiratory fitness between preschool children with normal and excess body adipose ~ An observational study

Objective

Overweight and obesity in preschoolers might develop into childhood and even adulthood obesity. Overweight and obesity have been shown to be negatively related with cardiorespiratory fitness (CRF) in children and adults but few studies did among preschoolers. We aimed to evaluate whether excess body adipose is negatively associated with CRF in both the submaximal and maximal effort of preschool children in exercise testing and to examine if there is difference to achieve maximal effort during exercise testing between preschoolers with normal and excess body adipose.

Methods

Data of 106 preschoolers aged 4–6 that received symptom-limited treadmill exercise testing was analyzed. Anthropometry was measured by vector bioelectrical impedance analysis. Excess body adipose was defined as (1) ‘overweight’ and ‘obesity’ by body mass index (BMI), (2) fat mass index (FMI) greater than the sex- and age-specific 75th percentile of whole subjects, and (3) fat-free mass index (FFMI) smaller than the sex- and age-specific 25th percentile. CRF was indicated by metabolic equivalent (MET) at anaerobic threshold (AT MET), peak MET, oxygen uptake efficiency slope (OUES) calculated by the 50% (OUES-50) and the entire (OUES-100) duration of the exercise testing.

Results

Preschoolers with excess body adipose by three different definitions (BMI, FMI, and FFMI) all had poorer ability to perform maximal effort (p = 0.004, 0.043, and 0.007, respectively). Preschoolers with excess body adipose by BMI and FFMI classifications had lower OUES-50 (p = 0.018, and 0.001, respectively), and lower OUES-100 (p = 0.004, and 0.001, respectively) than peers with normal body adipose during exercise testing while those with excess body adipose by FMI classification showed no significant differences from peers with normal body adipose in both OUES-50 and OUES-100.

Conclusions

Preschoolers with excess body adipose had lower CRF significantly during treadmill exercise testing. Weight control and health promotion should start as early as possible.

Waist Circumference and Healthy Lifestyle Preferences/Knowledge Monitoring in a Preschool Obesity Prevention Program

Weight and body mass index (BMI) changes appear to be poor measures for assessing the success of most pediatric obesity prevention programs (POPP). The aim of this study is to evaluate the effectiveness of the preschool-age prevention program (3P) in improving and maintaining overtime preschoolers' knowledge/preferences about healthy nutrition and physical activity (PA), and the relationship between acquired healthy behaviors and anthropometrics including waist circumference (WC). Twenty-five preschoolers underwent a 24-month healthy lifestyle multi-component pilot intervention followed by a one-year wash-out period; 25 age-matched served as controls. Anthropometric/behavioral data were monitored. After the 2-year study and wash-out, the rates of children overweight and with obesity decreased only in the intervention group, where, also, normal-weight children with visceral obesity attained WC normal values (p = 0.048). While mean values of BMI Z-scores remained unchanged in both the intervention and control groups, WC (values and percentiles) showed a significant reduction only in the intervention group. Children's adherence to the Mediterranean diet remained acceptable among the entire sample. Although daily sweet beverage consumption remained unchanged in both groups, knowledge/preferences improved significantly more in the intervention group. In conclusion, WC may be more sensitive than BMI for monitoring preschoolers in POPP and reflects healthy behavioral changes acquired during the intervention.

Interventions for preventing obesity in children

EDITORIAL NOTE

This Cochrane review is now out of date and should not be used for reference. It has been split into four age groups and updated. Please refer to the 5‐11 and 12‐18 age group Cochrane reviews which were published in May 2024: https://doi.org/10.1002/14651858.CD015328.pub2 https://doi.org/10.1002/14651858.CD015330.pub2 The 2‐4 age group Cochrane review is planned for publication in September 2024.

BACKGROUND

Prevention of childhood obesity is an international public health priority given the significant impact of obesity on acute and chronic diseases, general health, development and well-being. The international evidence base for strategies to prevent obesity is very large and is accumulating rapidly. This is an update of a previous review.

OBJECTIVES

To determine the effectiveness of a range of interventions that include diet or physical activity components, or both, designed to prevent obesity in children.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PsychINFO and CINAHL in June 2015. We re-ran the search from June 2015 to January 2018 and included a search of trial registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of diet or physical activity interventions, or combined diet and physical activity interventions, for preventing overweight or obesity in children (0-17 years) that reported outcomes at a minimum of 12 weeks from baseline.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed risk-of-bias and evaluated overall certainty of the evidence using GRADE. We extracted data on adiposity outcomes, sociodemographic characteristics, adverse events, intervention process and costs. We meta-analysed data as guided by the Cochrane Handbook for Systematic Reviews of Interventions and presented separate meta-analyses by age group for child 0 to 5 years, 6 to 12 years, and 13 to 18 years for zBMI and BMI.

MAIN RESULTS

We included 153 RCTs, mostly from the USA or Europe. Thirteen studies were based in upper-middle-income countries (UMIC: Brazil, Ecuador, Lebanon, Mexico, Thailand, Turkey, US-Mexico border), and one was based in a lower middle-income country (LMIC: Egypt). The majority (85) targeted children aged 6 to 12 years.Children aged 0-5 years: There is moderate-certainty evidence from 16 RCTs (n = 6261) that diet combined with physical activity interventions, compared with control, reduced BMI (mean difference (MD) -0.07 kg/m2, 95% confidence interval (CI) -0.14 to -0.01), and had a similar effect (11 RCTs, n = 5536) on zBMI (MD -0.11, 95% CI -0.21 to 0.01). Neither diet (moderate-certainty evidence) nor physical activity interventions alone (high-certainty evidence) compared with control reduced BMI (physical activity alone: MD -0.22 kg/m2, 95% CI -0.44 to 0.01) or zBMI (diet alone: MD -0.14, 95% CI -0.32 to 0.04; physical activity alone: MD 0.01, 95% CI -0.10 to 0.13) in children aged 0-5 years.Children aged 6 to 12 years: There is moderate-certainty evidence from 14 RCTs (n = 16,410) that physical activity interventions, compared with control, reduced BMI (MD -0.10 kg/m2, 95% CI -0.14 to -0.05). However, there is moderate-certainty evidence that they had little or no effect on zBMI (MD -0.02, 95% CI -0.06 to 0.02). There is low-certainty evidence from 20 RCTs (n = 24,043) that diet combined with physical activity interventions, compared with control, reduced zBMI (MD -0.05 kg/m2, 95% CI -0.10 to -0.01). There is high-certainty evidence that diet interventions, compared with control, had little impact on zBMI (MD -0.03, 95% CI -0.06 to 0.01) or BMI (-0.02 kg/m2, 95% CI -0.11 to 0.06).Children aged 13 to 18 years: There is very low-certainty evidence that physical activity interventions, compared with control reduced BMI (MD -1.53 kg/m2, 95% CI -2.67 to -0.39; 4 RCTs; n = 720); and low-certainty evidence for a reduction in zBMI (MD -0.2, 95% CI -0.3 to -0.1; 1 RCT; n = 100). There is low-certainty evidence from eight RCTs (n = 16,583) that diet combined with physical activity interventions, compared with control, had no effect on BMI (MD -0.02 kg/m2, 95% CI -0.10 to 0.05); or zBMI (MD 0.01, 95% CI -0.05 to 0.07; 6 RCTs; n = 16,543). Evidence from two RCTs (low-certainty evidence; n = 294) found no effect of diet interventions on BMI.Direct comparisons of interventions: Two RCTs reported data directly comparing diet with either physical activity or diet combined with physical activity interventions for children aged 6 to 12 years and reported no differences.Heterogeneity was apparent in the results from all three age groups, which could not be entirely explained by setting or duration of the interventions. Where reported, interventions did not appear to result in adverse effects (16 RCTs) or increase health inequalities (gender: 30 RCTs; socioeconomic status: 18 RCTs), although relatively few studies examined these factors.Re-running the searches in January 2018 identified 315 records with potential relevance to this review, which will be synthesised in the next update.

AUTHORS' CONCLUSIONS

Interventions that include diet combined with physical activity interventions can reduce the risk of obesity (zBMI and BMI) in young children aged 0 to 5 years. There is weaker evidence from a single study that dietary interventions may be beneficial.However, interventions that focus only on physical activity do not appear to be effective in children of this age. In contrast, interventions that only focus on physical activity can reduce the risk of obesity (BMI) in children aged 6 to 12 years, and adolescents aged 13 to 18 years. In these age groups, there is no evidence that interventions that only focus on diet are effective, and some evidence that diet combined with physical activity interventions may be effective. Importantly, this updated review also suggests that interventions to prevent childhood obesity do not appear to result in adverse effects or health inequalities.The review will not be updated in its current form. To manage the growth in RCTs of child obesity prevention interventions, in future, this review will be split into three separate reviews based on child age.