A longitudinal causal graph analysis investigating modifiable risk factors and obesity in a European cohort of children and adolescents.

Childhood obesity is a complex disorder that appears to be influenced by an interacting system of many factors. Taking this complexity into account, we aim to investigate the causal structure underlying childhood obesity. Our focus is on identifying potential early, direct or indirect, causes of obesity which may be promising targets for prevention strategies. Using a causal discovery algorithm, we estimate a cohort causal graph (CCG) over the life course from childhood to adolescence. We adapt a popular method, the so-called PC-algorithm, to deal with missing values by multiple imputation, with mixed discrete and continuous variables, and that takes background knowledge such as the time-structure of cohort data into account. The algorithm is then applied to learn the causal structure among 51 variables including obesity, early life factors, diet, lifestyle, insulin resistance, puberty stage and cultural background of 5112 children from the European IDEFICS/I.Family cohort across three waves (2007-2014). The robustness of the learned causal structure is addressed in a series of alternative and sensitivity analyses; in particular, we use bootstrap resamples to assess the stability of aspects of the learned CCG. Our results suggest some but only indirect possible causal paths from early modifiable risk factors, such as audio-visual media consumption and physical activity, to obesity (measured by age- and sex-adjusted BMI z-scores) 6 years later.

The role of psychosocial well-being and emotion-driven impulsiveness in food choices of European adolescents.

BACKGROUND: It is unclear whether a hypothetical intervention targeting either psychosocial well-being or emotion-driven impulsiveness is more effective in reducing unhealthy food choices. Therefore, we aimed to compare the (separate) causal effects of psychosocial well-being and emotion-driven impulsiveness on European adolescents' sweet and fat propensity. METHODS: We included 2,065 participants of the IDEFICS/I.Family cohort (mean age: 13.4) providing self-reported data on sweet propensity (score range: 0 to 68.4), fat propensity (range: 0 to 72.6), emotion-driven impulsiveness using the UPPS-P negative urgency subscale, and psychosocial well-being using the KINDLR Questionnaire. We estimated, separately, the average causal effects of psychosocial well-being and emotion-driven impulsiveness on sweet and fat propensity applying a semi-parametric doubly robust method (targeted maximum likelihood estimation). Further, we investigated a potential indirect effect of psychosocial well-being on sweet and fat propensity mediated via emotion-driven impulsiveness using a causal mediation analysis. RESULTS: If all adolescents, hypothetically, had high levels of psychosocial well-being, compared to low levels, we estimated a decrease in average sweet propensity by 1.43 [95%-confidence interval: 0.25 to 2.61]. A smaller effect was estimated for fat propensity. Similarly, if all adolescents had high levels of emotion-driven impulsiveness, compared to low levels, average sweet propensity would be decreased by 2.07 [0.87 to 3.26] and average fat propensity by 1.85 [0.81 to 2.88]. The indirect effect of psychosocial well-being via emotion-driven impulsiveness was 0.61 [0.24 to 1.09] for average sweet propensity and 0.55 [0.13 to 0.86] for average fat propensity. CONCLUSIONS: An intervention targeting emotion-driven impulsiveness, compared to psychosocial well-being, would be marginally more effective in reducing sweet and fat propensity in adolescents.

Digital media exposure and cognitive functioning in European children and adolescents of the I.Family study.

The digital environment can pose health risks through exposure to unhealthy content. Yet, little is known about its relation to children's cognitive functioning. This study investigates the association between digital media (DM) exposure and children's cognitive functioning. This cross-sectional study is based on examinations of children aged 8-18 years (N = 8673) of the I.Family cohort (2013-2014). Exposure to television, computer, smartphone and internet was self-reported (hours/day). Media multitasking (MMT) was defined as simultaneous use of computers with other digital or non-screen-based activities. Standard instruments were used to assess cognitive inflexibility (score: 0-39), decision-making ability (- 100 to + 100) and impulsivity (12-48). Adjusted regression coefficients and 99.9%CIs were calculated by generalized linear mixed-effects models. In total, 3261 participants provided data for impulsivity, 3441 for cognitive inflexibility and 4046 for decision-making. Exposure to smartphones and media multitasking were positively associated with impulsivity (ßsmartphone = 0.74; 99.9%CI = 0.42-1.07; ßMMT = 0.73; 99.9%CI = 0.35-1.12) and cognitive inflexibility (ßsmartphone = 0.32; 99.9%CI = -0.02-0.66; ßMMT = 0.39; 99.9%CI = 0.01-0.77) while being inversely associated with decision-making ability. Extensive smartphone/internet exposure combined with low computer/medium TV exposure was associated with higher impulsivity and cognitive inflexibility scores, especially in girls. DM exposure is adversely associated with cognitive functioning in children and adolescents. Children require protection against the likely adverse impact of digital environment.

The association between commuting and cardiovascular disease: A biomarker-based analysis of cross-sectional cohort data from the UK Biobank.

This study used cross-sectional UK Biobank data to estimate the influence of active and passive commuting modes and commuting distance on cardiovascular disease (CVD) -related biomarkers as measures of health outcomes. The analysis applied logistic regression to assess the risk of exhibiting individual biomarker values outside a predefined reference interval and standard linear regression to estimate the relation between commuting practices and a composite CVD index. The study sample comprised 208,893 UK Biobank baseline survey participants aged 40 to 69 who use various modes of transport to commute to work at least once a week. Participants were recruited and interviewed between 2006 and 2010 at 22 centers geographically dispersed across England, Scotland, and Wales. The data set included these participants' sociodemographic and health-related information, including lifestyle indicators and biological measures. The primary outcome was a shift from low to high-risk blood serum levels in eight cardiovascular biomarkers: total cholesterol, low density lipoprotein, high density lipoprotein, triglycerides, apolipoprotein A and B, C-reactive protein, and lipoprotein (a). Our results indicated a small negative association between the composite risk index for CVD biomarkers and weekly commuting distance. Although estimates for active commuting modes (cycling, walking) may admittedly be sensitive to different covariate adjustments, our specifications show them to be positively associated with select CVD biomarkers. Commuting long distances by car is negatively associated with CVD-related biomarkers, while cycling and walking might be positively associated. This biomarker-based evidence, although limited, is less susceptible to residual confounding than that from distant outcomes like CVD mortality.

What we know about the actual implementation process of public physical activity policies: results from a scoping review.

BACKGROUND: Physical inactivity rates have remained high worldwide since 2001. Public policies are an essential upstream lever to target individual physical activity (PA) behaviour. However, implementers have different strategies and face implementation challenges that are poorly understood. The present study analyzes the implementation processes of public policies to promote PA in terms of: (i) the policies covered and their legal quality, (ii) the actors and stakeholders involved in the implementation process and (iii) the used implementation strategies (vertical, horizontal or a mix). METHODS: A scoping review was systematically conducted (registered Open Science Framework: osf.io/7w84q/), searching 10 databases and grey literature until March 2022. Of the 7741 titles and abstracts identified initially, 10 studies were included. RESULTS: The current evidence includes high-income countries (USA, n = 7; UK, New Zealand and Oman, n = 1 each). Policy areas covered are education (school sector) and PA promotion in general (national PA plans or city-wide approaches). The legal classification ranges from laws (school sector) to coordination and budgeting to non-legally binding recommendations. The jurisdictions covered were federal (n = 4), state (n = 1), county (n = 1), school district (n = 1) and city (n = 3). Implementation strategies for city-wide approaches are characterized by a coordinated approach with vertical and horizontal integration; federal PA policies by a mix of implementation strategies; and the school sector by a strict horizontal top-down integration without the involvement of other actors. CONCLUSION: Implementation strategies differ by policy field. Therefore, continuous evaluation of the implementation process is necessary to align policy implementation with policy goals to promote individual PA behaviour.

Sustainable Urban Mobility Plans: implementation process and indicators to evaluate effects on physical activity.

BACKGROUND: Active mobility and public transport increase physical activity (PA) levels. With varying intensity and effectiveness, European cities implement Sustainable Urban Mobility Plans (SUMPs) to spur transport-related PA. Therefore, we aim to examine drivers and barriers to SUMP implementation and assess its influence on PA across European cities. METHODS: We screened policy reports to gain insights into SUMP implementation in one Danish, two German and two Polish cities. Further, we conducted semi-structured interviews with SUMP stakeholders in these cities to explore their experiences with SUMP implementation. Thematic analysis of interview transcripts was applied to identify similarities and differences across cities. To assess the effect of SUMP implementation on PA, we searched for data on indicators of transport-related PA. RESULTS: All investigated cities are committed to sustainable mobility. Nonetheless, complex institutional structures, the dominant role of motorized traffic as well as complex regional and local policy integration hamper SUMP implementation. Danish, German and Polish cities face different contexts in terms of financing, national guidelines and the prominence of sustainability as a policy objective. Each city adopts unique indicators for monitoring the effects of SUMPs on transport-related PA. The variety of indicators and limited data availability impede a comparative evaluation across cities. Constrained by this restriction, we identified motorization rate, modal split and public transport ridership as suitable indicators. CONCLUSIONS: Local idiosyncrasies need to be accounted for when assessing the implementation of SUMPs. Nonetheless, consistent indicators and data transparency are essential for comparing the effectiveness of SUMPs and their impact on PA.

Healthy eating in the wild: An experience-sampling study of how food environments and situational factors shape out-of-home dietary success.

Across many parts of the world, people increasingly eat out-of-home. Simultaneously, many people strive to eat a healthier diet, but it remains unclear to what extent and how eating out helps or hinders people in achieving their dietary goals. The present study investigated how characteristics of the physical micro-environment in out-of-home food outlets (e.g., cafeterias, supermarkets, and restaurants) influence the healthiness of food choices among a sample of German adults with a goal to eat healthier. We used an experience sampling method to obtain detailed information about people's motivation for selecting a specific food outlet and the outlet's micro-environment. We further asked for people's mood, visceral state, and thoughts during their food choice and obtained evaluations of food choices reported near their occurrence and in externally valid conditions. The data was collected via a mobile app over a period of six to eleven days between November and December of 2018 in Germany with a sample of 409 participants (nobs = 6447). We find that even health-conscious people select food outlets and their respective micro-environments based on short-term goals, such as ease, taste, and speed of a consumption episode rather than long-term health outcomes. Using multiple regression, we show that micro-environments that promote healthy food, make such food more appealing and easier to select facilitate healthy food choices. We further identify some of the psychological mechanisms through which the micro-environment can affect food choices, as well as how individual characteristics moderate the relationship between specific micro-environmental factors and goal success. Taken together, our findings suggest the opportunity for, and arguably also necessity of, reshaping food environments to better facilitate healthier choices and support public health in the face of increasing out-of-home food consumption and the adverse consequences of unhealthy diets.

Sugar-sweetened beverage tax implementation processes: results of a scoping review.

Taxing sugar-sweetened beverages (SSB) is seen as a win-win situation for governments. It is argued that SSB taxes are relatively easy to implement from a practical perspective compared to for example other nutrition policies. However, the implementation of SSB taxation laws does not happen by itself. Therefore, this work examines implementation processes for SSB taxation in terms of (1) pre-implementation context, (2) taxation instruments used and (3) interactions in the implementation process. Ten databases and grey literature were systematically searched for studies reporting on SSB taxation implementation processes up to February 2020. All studies (N = 1248) were screened independently by two reviewers according to predefined criteria. The selection of variables to be extracted was based on the policy cycle heuristic and informed by intervention implementation research. Information on the process of implementing SSB taxation is limited. Only six cases based on three publications were identified, indicating a gap in this research area. SSB taxation implementation was accomplished by hiring a subcontractor for the implementation or using pre-existing tax collection structures. Political and public support within the implementation process seems to be supportive for the city of Berkeley and for Portugal but was not reported for the Pacific Islands. However, the existing data are very limited, and further research on SSB taxation implementation processes is needed to determine whether the aim of the policy and the envisaged outcome are linked in practice. Registration The protocol was registered with the Open Science Framework (OSF) (osf.io/7w84q/).

Battle of the primes - The effect and interplay of health and hedonic primes on food choice.

People making food choices are often exposed to different cues that can activate relevant goals that influence the choice outcome. Hedonic goals are frequently primed by advertising while health policy enlists primes that activate health goals in the moment of food decision-making - e.g., healthy food labels. However, little is known about the effect of such goal-priming cues on the population level and how people respond when exposed to both types of primes simultaneously. The results of this study, based on a large, representative sample (N = 1200), show no effect of health-goal priming on healthy food choices. Being exposed to a sole hedonic prime, however, reduces healthy choices by 3%. This effect completely disappeared when both primes were presented at the same time. All effects remained insensitive to people's gender, hunger status, level of dietary restraint, and BMI. These findings cast doubt over the effectiveness of health goal primes as a tool to increase healthy food choices but suggest a protective effect against competing hedonic primes and could thereby prevent less healthy choices.

"Corona Cooking": The interrelation between emotional response to the first lockdown during the COVID-19 pandemic and cooking attitudes and behaviour in Denmark.

For this study, the authors measured attitudes toward shopping for food and cooking, before and during the first lockdown due to the COVID-19 pandemic, among a sample of 526 Danish consumers, using an online survey. To analyse changes due to the lockdown, they applied a latent class Markov model, which revealed four states: middle of the road, love cooking (and like shopping), like shopping and cooking, and do not like shopping or cooking. In estimating transition probabilities, the findings reveal that most respondents remained in the same state before and during the lockdown, but those that changed were more likely to exhibit relatively higher liking of shopping and cooking. These states also reflect variations in people's food literacy and self-reported food consumption. Finally, respondents with stronger negative emotional reactions to the lockdown were more likely to change their states.

Associations Between Psychosocial Well-Being, Stressful Life Events and Emotion-Driven Impulsiveness in European Adolescents.

Knowing the extent to which mental well-being and stressful life events during adolescence contribute to personality characteristics related to risk-taking behaviors, such as emotion-driven impulsiveness, is highly relevant for the development of health promotion measures. This study examined whether psychosocial well-being and different stressful life events are associated with emotion-driven impulsiveness. In total, 3,031 adolescents (52% girls; Mage = 13.6 years) were included from the I. Family Study, a cross-sectional examination on lifestyle-related behaviors conducted across eight European countries in 2013/14. Linear mixed-effects regression models showed that higher psychosocial well-being was associated with lower emotion-driven impulsiveness independent of socio-demographic, health-related, and parental variables. A higher number of stressful life events was associated with higher emotion-driven impulsiveness. Psychosocial well-being and stressful life events need to be further considered in the development and tailoring of health promotion strategies that aim to reduce emotion-driven impulsiveness.

Associations of Sleep Duration and Screen Time with Incidence of Overweight in European Children: The IDEFICS/I.Family Cohort.

INTRODUCTION: Over the past decades, children have been increasingly using screen devices, while at the same time their sleep duration has decreased. Both behaviors have been associated with excess weight, and it is possible they act as mutually reinforcing behaviors for weight gain. The aim of the study was to explore independent, prospective associations of screen time and sleep duration with incident overweight in a sample of European children. METHODS: Data from 4,285 children of the IDEFICS/I.Family cohort who were followed up from 2009/2010 to 2013/2014 were analyzed. Hours per day of screen time and of sleep duration were reported by parents at baseline. Logistic regression analyses were carried out in separate and mutually adjusted models controlled for sex, age, European country region, parental level of education, and baseline BMI z-scores. RESULTS: Among normal weight children at baseline (N = 3,734), separate models suggest that every hour increase in screen time and every hour decrease in sleep duration were associated with higher odds of the child becoming overweight or obese at follow-up (OR = 1.16, 95% CI: 1.02-1.32 and OR = 1.23, 95% CI: 1.05-1.43, respectively). In the mutually adjusted model, both associations were attenuated slightly ( screen time OR = 1.13, 95% CI: 0.99-1.28; sleep duration OR = 1.20, 95% CI: 1.03-1.40), being consistently somewhat stronger for sleep duration. DISCUSSION/CONCLUSION: Both screen time and sleep duration increased the incidence of overweight or obesity by 13-20%. Interventions that include an emphasis on adequate sleep and minimal screen time are needed to establish their causal role in the prevention of overweight and obesity among European children.

Media use trajectories and risk of metabolic syndrome in European children and adolescents: the IDEFICS/I.Family cohort.

BACKGROUND: Media use may influence metabolic syndrome (MetS) in children. Yet, longitudinal studies are scarce. This study aims to evaluate the longitudinal association of childhood digital media (DM) use trajectories with MetS and its components. METHODS: Children from Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain and Sweden participating in the IDEFICS/I.Family cohort were examined at baseline (W1: 2007/2008) and then followed-up at two examination waves (W2: 2009/2010 and W3: 2013/2014). DM use (hours/day) was calculated as sum of television viewing, computer/game console and internet use. MetS z-score was calculated as sum of age- and sex-specific z-scores of four components: waist circumference, blood pressure, dyslipidemia (mean of triglycerides and HDL-cholesterol-1) and homeostasis model assessment for insulin resistance (HOMA-IR). Unfavorable monitoring levels of MetS and its components were identified (cut-off: ≥ 90th percentile of each score). Children aged 2-16 years with ≥ 2 observations (W1/W2; W1/W3; W2/W3; W1/W2/W3) were eligible for the analysis. A two-step procedure was conducted: first, individual age-dependent DM trajectories were calculated using linear mixed regressions based on random intercept (hours/day) and linear slopes (hours/day/year) and used as exposure measures in association with MetS at a second step. Trajectories were further dichotomized if children increased their DM duration over time above or below the mean. RESULTS: 10,359 children and adolescents (20,075 total observations, 50.3% females, mean age = 7.9, SD = 2.7) were included. DM exposure increased as children grew older (from 2.2 h/day at 2 years to 4.2 h/day at 16 years). Estonian children showed the steepest DM increase; Spanish children the lowest. The prevalence of MetS at last follow-up was 5.5%. Increasing media use trajectories were positively associated with z-scores of MetS (slope: ß = 0.54, 95%CI = 0.20-0.88; intercept: ß = 0.07, 95%CI = 0.02-0.13), and its components after adjustment for puberty, diet and other confounders. Children with increasing DM trajectories above mean had a 30% higher risk of developing MetS (slope: OR = 1.30, 95%CI = 1.04-1.62). Boys developed steeper DM use trajectories and higher risk for MetS compared to girls. CONCLUSIONS: Digital media use appears to be a risk factor for the development of MetS in children and adolescents. These results are of utmost importance for pediatricians and the development of health policies to prevent cardio-metabolic disorders later in life. TRIAL REGISTRATION: ISRCTN, ISRCTN62310987 . Registered 23 February 2018- retrospectively registered.

Ultra-processed foods consumption and diet quality of European children, adolescents and adults: Results from the I.Family study.

BACKGROUND AND AIMS: Food processing has been indicated as a factor capable of negatively affecting the global food system, including the profile of consumers' diets. The objectives of the present study were to provide a description of the consumption of ultra-processed foods (UPFs) in the large population of children, adolescents and adults from eight European countries participating to the I.Family study, and to investigate the association between UPFs intake and nutritional quality of the diet. METHODS AND RESULTS: Dietary intake was assessed using a 24-h dietary recall. The quality of the diet was evaluated by the Healthy Dietary Adherence Score (HDAS) using an FFQ. UPFs were classified according to the NOVA classification. Almost half of the daily energy intake of the 7073 participants came from UPFs, and this trend decreased progressively with age. UPFs contributed more than 50 % of the daily intake of total and saturated fat, carbohydrates and about 70 % of sugars intake in children and adolescents. No differences in UPFs consumption were found according to the educational and socio-economic status of the population. Energy intake increased across the quintiles of UPFs intake, while HDAS decreased. The frequency of consumption of fruit and vegetable, fish, and fibre rich foods was low in the fifth quintile of UPFs intake, both in adolescents and in adults. The consumption of foods rich in calories and low in nutritional content, operationally defined as "junk food", was significantly higher in the fifth quintile. CONCLUSIONS: In the population of the European I.Family study, UPFs contributed a large proportion of the daily energy intake, especially in children and adolescents. Higher consumption of UPFs was associated with a lower quality of the diet. REGISTRATION NUMBER FOR CLINICAL TRIALS: ISRCTN62310987.

Trajectories of objectively measured physical activity and childhood overweight: longitudinal analysis of the IDEFICS/I.Family cohort.

BACKGROUND: Since only few longitudinal studies with appropriate study designs investigated the relationship between objectively measured physical activity (PA) and overweight, the degree PA can prevent excess weight gain in children, remains unclear. Moreover, evidence is limited on how childhood overweight determines PA during childhood. Therefore, we analyzed longitudinal trajectories of objectively measured PA and their bi-directional association with weight trajectories of children at 2- and 6-year follow-ups. METHODS: Longitudinal data of three subsequent measurements from the IDEFICS/I.Family cohort study were used to analyze the bi-directional association between moderate-to-vigorous PA (MVPA) and weight status by means of multilevel regression models. Analyses comprised 3393 (2-year follow-up) and 1899 (6-year follow-up) children aged 2-15.9 years from eight European countries with valid accelerometer data and body mass index (BMI) measurements. For categorized analyses, children's weight status was categorized as normal weight or overweight (cutoff: 90th percentile of BMI) and children's PA as (in-) sufficiently active (cutoffs: 30, 45 and 60 min of MVPA per day). RESULTS: Children engaging in at least 60 min MVPA daily at baseline and follow-ups had a lower odds of becoming overweight (odds ratio [OR] at 2-year follow-up: 0.546, 95% CI: 0.378, 0.789 and 6-year follow-up: 0.393, 95% CI: 0.242, 0.638), compared to less active children. Similar associations were found for 45 min MVPA daily. On the other side, children who became overweight had the lowest odds to achieve 45 or 60 min MVPA daily (ORs: 0.459 to 0.634), compared to normal weight children. CONCLUSIONS: Bi-directional associations between MVPA and weight status were observed. In summary, at least 60 min MVPA are still recommended for the prevention of childhood overweight. To prevent excess weight gain, 45 min MVPA per day also showed preventive effects.

Digital Media Use in Association with Sensory Taste Preferences in European Children and Adolescents-Results from the I.Family Study.

Digital media (DM) influences children's food choice. We aim to investigate associations between DM use and taste preferences (TP) for sweet, fatty, bitter, and salty in European children and adolescents. Individuals aged 6-17 years (N = 7094) providing cross-sectional data for DM use: television (TV), computer/game console (PC), smartphone and internet, were included. Children (6 to <12 years) and adolescents (≥12 years) completed a Food and Beverage Preference Questionnaire; scores were calculated for sweet, fatty, salty and bitter preference and categorized (high vs. low). Logistic regression was used to calculate odds ratios as association measures between DM exposure and TP. On average, individuals used media for 2.4 h/day (SD = 1.7). Increasing exposures to DM were associated positively with sweet, fatty and salty TP, while inversely with bitter preference. In female adolescents, DM exposure for >2 h/day was associated with sweet (OR = 1.27, 95% CI = 1.02-1.57) and fatty preference (OR = 1.37; 95% CI = 1.10-1.70). Internet exposure was inversely associated with bitter preference, notably in male adolescents (OR = 0.65, 95% CI = 0.50-0.84), but positively associated with salty preference (OR = 1.29, 95% CI = 1.02-1.64). DM exposure was associated with sweet, fatty, salty and bitter TP in children and adolescents, serving as the basis for future longitudinal studies to shed light on the underlying mechanism by which DM exposure may determine eating habits.

Nudging healthier food choices in a cafeteria setting: A sequential multi-intervention field study.

Creating more health-fostering environments is high on the agenda of public and private actors. The behavioral approach to nudge people towards healthier food choices is gaining popularity despite limited understanding about where, and for whom, which specific nudges work. This study contributes by reporting on three different nudging interventions in the same setting and presents effects on different sub-populations. We find overall small effects that are heterogeneous, ranging from robustly more to even less healthy choices. We discuss the importance of transparency and reactance to health interventions and the potential interplay of interventions with habitual behavior among different sub-populations.

Weight Status and BMI-Related Traits in Adolescent Friendship Groups and Role of Sociodemographic Factors: The European IDEFICS/I.Family Cohort.

BACKGROUND: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. METHODS: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. RESULTS: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. CONCLUSION: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987).

A cross-sectional study of obesogenic behaviours and family rules according to family structure in European children.

BACKGROUND: There has been an increase in children growing up in non-traditional families, such as single-parent and blended families. Children from such families have a higher prevalence of obesity and poorer health outcomes, but research on the relationship with obesogenic behaviours is limited. OBJECTIVES: Therefore, the aim of this study was to investigate whether there are associations between family structures and obesogenic behaviours and related family rules in European children and adolescents. METHODS: The sample included 7664 children (mean age ± SD: 10.9 ± 2.9) from 4923 families who were participants of the multi-centre I.Family study (2013/2014) conducted in 8 European countries. Family structure was assessed by a detailed interview on kinship and household. Obesogenic behaviours (screen time, sleep duration, consumption of sugar-sweetened beverages (SSBs)) and family rules (rules for computer and television, bedtime routine, availability of SSBs during meals) were determined by standardized questionnaires. Multilevel mixed-effects linear and logistic regression models were used to model the associations of family structure with obesogenic behaviours and family rules. Sex, age, parental education level, number of children and adults in the household and BMI z-score were covariates in the models. Two-parent biological families were set as the reference category. RESULTS: Children from single-parent families were less likely to have family rules regarding screen time (OR: 0.62, 95% CI: 0.40-0.94, p = 0.026) with higher reported hours of screen time per week (ß = 2.70 h/week, 95% CI: 1.39-4.00, p < 0.001). The frequency of weekly SSB consumption differed by family structure in a sex-specific manner: girls from single-parent (ß = 3.19 frequency/week, 95% CI: 0.91-5.47, p = 0.006) and boys from blended/adoptive families (ß = 3.01 frequency/week, 95% CI: 0.99-5.03, p = 0.004) consumed more SSBs. Sleep duration, bedtime routines and availability of SSBs during meals did not differ between children from these family structures. Parental education did not modify any of these associations. CONCLUSIONS: Parents in non-traditional family structures appear to experience more difficulties in restricting screen time and the intake of SSBs in their children than parents in traditional two-parent family structures. Our findings therefore suggest that additional support and effective strategies for parents in non-traditional families may help to reduce obesogenic behaviours in children from such family types.