Energy balance-related behaviours associated with overweight and obesity in preschool children

A systematic review just published online in the journal Obesity Reviews aimed to systematically identify dietary, physical activity and sedentary behaviours in preschool children (4-6 years of age) that are prospectively related to overweight or obesity later in childhood. Dr. Saskia te Velde is first author of this paper. Prospective studies published between 1990 and 2010 were selected from electronic data bases of scientific publications and 23 papers reporting on 15 different study samples could be included in the review. Strong evidence was found for an inverse association between total physical activity and overweight, i.e. the more the kids were physically active, the less likely they were overweight. Moderately strong evidence was found for a positive association between television viewing and overweight, thus the more they engaged in TV watching, the more likely they were to be overweight. In the reviewed studies dietary intake was assessed is so many different ways that insufficient evidence was found for an association between dietary intake or specific dietary behaviours and overweight. These results suggest that interventions aiming to prevent overweight among preschool children should focus on promotion of total physical activity and limitation of screen time and that further research is needed to establish whether and which dietary behaviours are important for obesity prevention in this age group. However, we also concluded and recommended that despite the lack of evidence for dietary behaviours from the present review, future interventions may already target specific dietary behaviours that are highly prevalent and for which there a clear rationale as well as preliminary evidence that these behaviours are associated with overweight.

A second paper in that same special issue of Obesity Reviews with Dr. Maartje van Stralen as first author reported on secondary analyses of different studies conducted across Europe on weight status and risk behaviors for overweight and obesity in pre-scholers. This study aimed to gain insight in the prevalence of overweight in European preschoolers (4–7 years), to identify energy balance-related behaviours associated with overweight/obesity; and to explore children at risk for overweight and obesity. Secondary analyses of six European data sets were conducted according to standardized protocols. Based on objectively measured height and weight, prevalence of overweight and obesity across the countries ranged from 8% to 30% and 1% to 13%, respectively, with highest rates in Southern European countries (i.e. Spain and Greece). Kids who spend more time in sedentary activities were more likley to be overweight/obese. We concluded that future obesity prevention interventions in preschoolers should target screen time giving specific attention to children from parents who are themselves overweight/obese and from lower socioeconomic positions.

Ice skating on Spaarne, near Haarlem

For the fourth year in a row, we have a few weeks of good frost, and the ice is nice and thick on many canals and lakes. Is skipped work for a few hours today to enjoy the ice and went for a nice ride on my skates on the Spaarne canal, near Haarlem.
See http://youtu.be/9-JZgCUlxKo for a video impression....

The importance of parental involvement in school-based programs to promote healthy nutrition and physical activity

Parental involvement is often advocated as important for school-based interventions, because parents are a main determinant of children's dietary and physical activity behaviors. We conducted a systematic review of the available scientific literature on this issue to explore the available scientific evidence for this claim. This review thus aimed at determining the impact of parental involvement in school-based obesity prevention interventions in children and adolescents. Our review was conducted as part of the ENERGY project, a European Commission-funded project to improve obesity prevention among school-aged children across Europe. The review was just published in the International Journal of Public Health. Wendy van Lippevelde, a PhD candidate from the University of Ghent was first author.
Akltough some positive effects of parental involvement were found on children's behaviours and behavioural determinants, the evidence was inconclusive. Maybe the most prominebt outcome of our review was that so few studies have been conducted that have explicetely tested the effect of parental involvement, and celarly more studies are needed to address this important issue.  There is a need for more studies comparing school-based interventions with and without a parental component, and dose, strategies and content of parental components of school-based interventions should be better reported in research articles.

Genetic and environmental Influences on screen-time behaviors among adolescents

In a paper with Dr.Niels van der Aa as first author, just published online by Arcives of Pediatric and Adolescent Medicine, we report on an investigation of the genetic and environmental influences on sedentary behavior, i.e. TV and computer time, among adolescents. The paper is based on analyes of cross sectional data from the Netherlands Twin Registrer. The Netherlands Twin Register (NTR) was established in 1987 at the Vrije Universiteit in Amsterdam for scientific research purposes. The study of twins and their family members can provide insight into what extent the causes of differences between individuals are determined by genetic and environmental influences. Prof. Dorret Boomsma, (or see her EMGO personal page) co-author of the paper, is the founder of this registry.

The study published in Archives shows that differences in sedentary behavior can to a large extend be explained by genetic factors, and that the importance of genetic influence increases from age 12 to age 20. To be a bit more specific, our data showed that variation in adolescent sedentary behavior was largely accounted for by genetic and nonshared environmental factors, whereas shared environmental factors account for a substantial part of the variation among younger adolescents. The shift from shared environmental factors in the etiology of sedentary behavior among younger adolescents to genetic and nonshared environmental factors among older adolescents has consequences for intervention programs that aim to reduce adolescents' screen-tme behaviors. These require specific tailoring to age groups and need to focus on peers and parents in early adolescence but on the youngsters themselves at later ages.

Screen time predicts weight gain but body fatness did not predict more screen time in boys

Screen time, i.e. TV viewing and computer time, has been found to be associated with overweight in children and adolescents. However, it is unclear if kids who are overweight start watching more TV or if kids who watch more TV are more likley to become overweight. The aim of a study just published in the International Journal of Behavioral Nutrition & Physical Activity examined the direction of the association between screen time and body fatness in Dutch adolescents. Dr. Teatske Altenburg was first author.

Longitudinal data of 465 Dutch adolescents (mean age at baseline 13 years, 53% boys) was used. Body fatness (objectively measured Body Mass Index (BMI), four skin folds and waist- and hip circumference), self-reported time spent watching TV and computer use, and aerobic fitness (shuttle run test) were assessed in all participants at three time points during 12 months. State of the art statistical analyses were conducted to see if screen time predicted body fatness in the following time period and/or whether body fatness predicted more screen time.

Time spent TV viewing did indeed predict changes in BMI and hip circumference in boys, but not in girls, in the subsequent period. Computer time significantly predicted increases in skinfolds in boys and girls and increases in BMI in girls. Body fatness did not predict any changes in screen time.
Our study thus only partly supports the widely posited hypothesis that more  screen time cause increases in body fatness. In addition, this study demonstrates that high levels of body fatness did not predict increases in screen time.

A review of worksite physical activity promotion interventions in Europe

In a paper just published in e-pub in Obesity Facts, we reviewed the effectiveness of physical activity promotion interventions in the worksite setting in Europe. Studies included (n = 33) were divided in 6 intervention categories. Moderate evidence of effectiveness was found for physical fitness outcomes with exercise training interventions and for physical activity outcomes with active commuting interventions. Although our review suggested that worksite interventions did result in more physical activity, our review showed no or inconclusive evidence for obesity-related outcomes for all intervention categories. We concluded that active commuting and exercise training appear as promising approaches to promote physical activity or fitness in the workplace. The effect of interventions on obesity-related outcomes remains to be further investigated.

Differences in fruit and vegetable intake among Dutch schoolchildren between 2003 and 2009

Fruit and vegetable (FV) intake in children in the Netherlands is much lower than recommended. Recurrent appraisal of intake levels is important for detecting changes in intake over time and to inform future interventions and policies. The aim of a study recently published in the International Journal of Behavioral Nutrition & Physical Activity was to investigate differences in fruit and vegetable intake, and whether these could be explained by differences in potential determinants of FV intake in 11-year-old Dutch schoolchildren, by comparing two school samples assessed in 2003 and 2009 in tow European Commission funded projects, i.e. the Pro Children and Pro Greens projects. In 2009, more children complied with the World Health Organization recommendation of 400g fruit and vegetables per day (17.0%) than in 2003 (11.8%). This difference was mainly explained by a difference in the parental demand regarding their child's intake, by differences in children's knowledge of recommended fruit intake levels and by whether parents faciliated their child's fruit intake. Vegetable intake was lower in the 2009 sample than in the 2003 sample but this difference could not be explained by the assessed mediators. The findings indicate that fruit intake among 11-year-olds improved somewhat between 2003 and 2009. Vegetable intake, however, appears to have declined somewhat between 2003 and 2009. Since a better knowledge of the recommendation, parental demand and facilitation explained most of the observed fruit consumption difference, future interventions may specifically address these potential mediators.