DXA measurements confirm that parental perceptions of elevated adiposity in young children are poor

Objective: To compare parental assessments of child body weight status with BMI measurements and determine whether children who are incorrectly classified differ in body composition from those whose parents correctly rate child weight. Also to ascertain whether children of obese parents differ from those of non‐obese parents in actual or perceived body weight. Research Methods and Procedures: Weights, heights, BMI, and waist girths of New Zealand children ages 3 to 8 years were determined. Fat mass, fat percentage, and lean mass were measured by DXA (n = 96). Parents classified child weight status as underweight, normal‐weight, slightly overweight, or overweight. Centers for Disease Control and Prevention 2000 percentiles of BMI were used. Results: Parents underestimated child weight status. Despite having 83% more fat mass than children with BMI values below the 85th percentile, only 7 of 31 children with BMI values at or above the 85th percentile were rated as slightly overweight or overweight. In the whole sample, participants whose weight status was underestimated by parents (40 of the 96 children) had l9% less fat mass but similar lean mass as children whose weight status was correctly classified. However, children of obese and non‐obese parents did not differ in body composition or anthropometry, and obese parents did not underestimate child weight more than non‐obese parents. Discussion: Because parents underestimate child weight, but BMI values at or above the 85th percentile identify high body fat well, advising parents of the BMI status of their children should improve strategies to prevent excessive fat gain in young children.     

Identifying patterns of eating and physical activity in children: a latent class analysis of obesity risk

We used latent class analysis (LCA) to identify heterogeneous subgroups with respect to behavioral obesity risk factors in a sample of 4th grade children (n = 997) residing in Southern California. Multiple dimensions assessing physical activity, eating and sedentary behavior, and weight perceptions were explored. A set of 11 latent class indicators were used in the analysis. The final model yielded a five-class solution: "High-sedentary, high-fat/high-sugar (HF/HS) snacks, not weight conscious," "dieting without exercise, weight conscious," "high-sedentary, HF/HS snacks, weight conscious," "active, healthy eating," and "low healthy, snack food, inactive, not weight conscious." The results suggested distinct subtypes of children with respect to obesity-related risk behaviors. Ethnicity, gender, and a socioeconomic status proxy variable significantly predicted the above latent classes. Overweight or obese weight status was determined based on the Centers for Disease Control and Prevention BMI (kg/m2)-for-age-and-sex percentile (overweight, 85th percentile ≤ BMI < 95th percentile; obese, 95th percentile ≤ BMI). The identified latent subgroup membership, in turn, was associated with the children's weight categories. The results suggest that intervention programs could be refined or targeted based on children's characteristics to promote effective pediatric obesity interventions.     

Association between family divorce and children's BMI and meal patterns: the GENDAI Study

The aim of this work was to explore the associations between family factors, including divorce, and children's overweight as well as eating and physical activity patterns in a population-based sample of healthy school-aged children. In this cross-sectional study, 1,138 children (53% girls; age: 11.2 +/- 0.7 years) from elementary schools in the Attica region participated. Their parents provided sociodemographic information, including their marital status. Overweight status classification was based on weight and height measurements and BMI evaluation. Children completed a physical activity checklist and a questionnaire on meal patterns and eating behaviors. The Eating Style score was calculated: the higher the score, the more frequent a child was engaged in less-structured feeding practices promoting food intake for reasons other than hunger. Analysis revealed significant association between family divorce and children's overweight: compared with children of married parents, those of divorced had significantly higher BMI levels (20.0 +/- 3.6 kg/m(2) vs. 21.3 +/- 3.4 kg/m(2), respectively, P = 0.007). Controlling for socioeconomic and physical activity factors, divorce remains a significant predictor of a higher BMI, along with older age, higher father's and mother's BMI, less children in the family, and more minutes of daily screen time. Children who had experienced a divorce in their family also reported higher Eating Style score, even after adjusting for potential confounders. In conclusion, in this sample of fifth and sixth graders, unfavorable family circumstances have been associated with children's overweight, as well as with aspects of their eating behavior, namely eating style in relation to conditions around food consumption and hunger, independent of other socioeconomic factors.     

Exposure to food advertising on television: Associations with children's fast food and soft drink consumption and obesity

There is insufficient research on the direct effects of food advertising on children's diet and diet-related health, particularly in non-experimental settings. We employ a nationally-representative sample from the Early Childhood Longitudinal Survey–Kindergarten Cohort (ECLS-K) and the Nielsen Company data on spot television advertising of cereals, fast food restaurants and soft drinks to children across the top 55 designated-market areas to estimate the relation between exposure to food advertising on television and children's food consumption and body weight. Our results suggest that soft drink and fast food television advertising is associated with increased consumption of soft drinks and fast food among elementary school children (Grade 5). Exposure to 100 incremental TV ads for sugar-sweetened carbonated soft drinks during 2002–2004 was associated with a 9.4% rise in children's consumption of soft drinks in 2004. The same increase in exposure to fast food advertising was associated with a 1.1% rise in children's consumption of fast food. There was no detectable link between advertising exposure and average body weight, but fast food advertising was significantly associated with body mass index for overweight and obese children (≥85th BMI percentile), revealing detectable effects for a vulnerable group of children. Exposure to advertising for calorie-dense nutrient-poor foods may increase overall consumption of unhealthy food categories.     

Early Postnatal BMI Adaptation Is Regulated During a Fixed Time Period and Mainly Depends on Maternal BMI

In the present study, we investigated whether there are critical time periods which influence the course of BMI during the first 6 years of life. From 5,433 children who participated in preschool examinations those 212 children were selected who crossed the BMI percentiles as a result of an extreme postnatal BMI rise (from <10th to 90th percentile) or fall (from >90th to <10th percentile) or who have persistently low or high BMI both at birth and at the age of 6 years. Forty children with a BMI close to the 50th percentile both at birth and age 6 years were selected to serve as controls. The courses of weight and height during the first 6 years of age were assessed and BMI was calculated. To identify influences connected with BMI development, we investigated genetic, social, nutritional, and other factors proceeding from the mother during pregnancy. Finally completed data sets of 57 children were available. Our study shows that during two critical time periods a significant move toward low or high BMI takes place among the groups: in early infancy from ～0.5 to 1.5 years and again from 5 to 6 years. At the age of 1.5 years the final state of BMI is already fixed in all study groups. Mothers of overweight 6‐year‐old children are overweight, whereas mothers of underweight 6‐year‐old children have a below‐normal BMI. All other investigated factors only had a minor influence on postnatal BMI development. We conclude that postnatal BMI development follows a fixed genetic program and is mainly programmed by maternal metabolism.     

Reference Growth Curves for Cypriot Children 6 to 17 Years of Age

Objective: The purpose of the study was to present smoothed percentiles for body weight and height, waist circumference, and body mass index (BMI) in Cypriot children and to compare their BMI 85th and 95th percentiles with those of children in other countries. Research Methods and Procedures: The study was a cross‐sectional study, including a representative sample of 2472 healthy children (49.1% boys) in Cyprus ages 6 to 17 years, who were evaluated during the 1999–2000 school year. Body weight and height and waist circumference were measured using standard procedures. BMI was calculated as weight in kilograms per height in square meters. Smoothed, sex‐specific percentiles for these variables were calculated using polynomial regression models. Crude weight, height, waist, and BMI percentile values are presented in sex‐specific tables and smoothed percentile curves are presented in charts. The 85th and 95th percentiles for BMI were compared with measurements from other countries, because of the concern of the upper limits of BMI in respect to the evaluation of obesity. Results: The 85th and 95th BMI percentile values are higher in Cypriot boys than in Swedish and Iranian boys through all ages and in girls ages 6 to 15 years, whereas after the age of 15 years, both Swedish and Iranian girls’ percentiles are equalized with their Cypriot peers. Discussion: Weight, height, waist circumference, and BMI values and charts are presented for the first time for Cypriot children and adolescents. Much concern should be addressed to the observation that for the majority of the Cypriot sample, the upper BMI limits are higher than the peers of developing and developed countries.     

Longitudinal study of body weight changes in children: who is gaining and who is losing weight

Cross-sectional studies have reported significant temporal increases in prevalence of childhood obesity in both genders and various racial groups, but recently the rise has subsided. Childhood obesity prevention trials suggest that, on average, overweight/obese children lose body weight and nonoverweight children gain weight. This investigation tested the hypothesis that overweight children lose body weight/fat and nonoverweight children gain body weight/fat using a longitudinal research design that did not include an obesity prevention program. The participants were 451 children in 4th to 6th grades at baseline. Height, weight, and body fat were measured at month 0 and month 28. Each child's BMI percentile score was calculated specific for their age, gender and height. Higher BMI percentile scores and percent body fat at baseline were associated with larger decreases in BMI and percent body fat after 28 months. The BMI percentile mean for African-American girls increased whereas BMI percentile means for white boys and girls and African-American boys were stable over the 28-month study period. Estimates of obesity and overweight prevalence were stable because incidence and remission were similar. These findings support the hypothesis that overweight children tend to lose body weight and nonoverweight children tend to gain body weight.     

A Pilot Randomized Controlled Trial of a Clinic and Home‐Based Behavioral Intervention to Decrease Obesity in Preschoolers

We evaluated the efficacy of a 6‐month clinic and home‐based behavioral intervention (Learning about Activity and Understanding Nutrition for Child Health; LAUNCH) to reduce obesity in preschool children ≥95th BMI percentile compared to enhanced standard of care (Pediatrician Counseling; PC). LAUNCH was a family‐based behavioral intervention that taught parents to use child behavior management strategies to increase healthy eating and activity for their children and themselves. PC presented the same diet and activity recommendations, but was delivered in a one‐time PC session. Eighteen children aged 2–5 years (mean 4.71 ± 1.01) with an average BMI percentile of 98 (±1.60) and an overweight parent were randomized to LAUNCH or PC. Assessments were conducted at baseline, 6 months (end of LAUNCH treatment) and 12 months (6 months following LAUNCH treatment). LAUNCH showed a significantly greater decrease on the primary outcomes of child at month 6 (post‐treatment) BMI z (?0.59 ± 0.17), BMI percentile (?2.4 ± 1.0), and weight gain (?2.7 kg ± 1.2) than PC and this difference was maintained at follow‐up (month 12). LAUNCH parents also had a significantly greater weight loss (?5.5 kg ± 0.9) at month 6 and 12 (?8.0 kg ± 3.5) than PC parents. Based on the data from this small sample, an intensive intervention that includes child behavior management strategies to improve healthy eating and activity appears more promising in reducing preschool obesity than a low intensity intervention that is typical of treatment that could be delivered in primary care.     

The association between childhood obesity and tooth eruption

Obesity is a growth-promoting process as evidenced by its effect on the timing of puberty. Although studies are limited, obesity has been shown to affect the timing of tooth eruption. Both the timing and sequence of tooth eruption are important to overall oral health. The purpose of this study was to examine the association between obesity and tooth eruption. Data were combined from three consecutive cycles (2001-2006) of the National Health and Nutrition Examination Survey (NHANES) and analyzed to examine associations between the number of teeth erupted (NET) and obesity status (BMI z-score >95th percentile BMI relative to the Centers for Disease Control and Prevention (CDC) growth reference) among children 5 up to 14 years of age, controlling for potential confounding by age, gender, race, and socioeconomic status (SES). Obesity is significantly associated with having a higher average NET during the mixed dentition period. On average, teeth of obese children erupted earlier than nonobese children with obese children having on average 1.44 more teeth erupted than nonobese children, after adjusting for age, gender, and race/ethnicity (P < 0.0001). SES was not a confounder of the observed associations. Obese children, on average, have significantly more teeth erupted than nonobese children after adjusting for gender, age, and race. These findings may have clinical importance in the area of dental and orthodontic medicine both in terms of risk for dental caries due to extended length of time exposed in the oral cavity and sequencing which may increase the likelihood of malocclusions.     

Observable Weight Distributions and Children's Individual Weight Assessment

Social networks theory suggests obesity is “contagious” within peer groups in that known friends highly influence weight. On the other hand, an alternative model suggests that observable weight distributions affect perception of one's own obesity level. We examine whether the BMI levels of the most obese classmates in the individual student's grade by gender is positively associated with “under‐assessment” of obesity and overweight (i.e., independently measured obesity or overweight, but subjective self‐assessment of normal weight). The data are the 2004–2005 School Physical Activity and Nutrition III (SPAN), a stratified, multistage probability sample of 4th, 8th, and 11th grade public school children in Texas. We used logistic regression to test whether the gender‐specific 85th percentile BMI level within the individual student's grade at their school is positively associated with “under‐assessment” of obesity and overweight. The results show that students are much more likely to under‐assess their own weight if the gender‐specific 85th percentile BMI level is higher in their grade at their school. These data suggest that observable weight distributions play a key role in the obesity epidemic.     

The relationship between chronotype and obesity in children and adolescent with attention deficit hyperactivity disorder

ABSTRACT

Children and adolescents with Attention De?cit Hyperactivity Disorder (ADHD) have a high prevalence of obesity, but the relationship between these two problems is not clear. Chronotype preferences may be one of the possible mechanisms underlying the link between ADHD and obesity. This is the ?rst study to investigate whether chronotype preferences are a mechanism linking ADHD symptoms to obesity in children and adolescents. This cross-sectional study included 110 drug-naive children and adolescents aged 7–17 years with ADHD. The Kiddie Schedule for Affective Disorders and Schizophrenia‐Present and Lifetime Version (K‐SADS‐PL) was used to diagnose ADHD or to exclude psychiatric comorbidity. The Conners’ Parents Rating Scale-Revised Short Version (CPRS-RS) and Children’s Chronotype Questionnaire (CCQ) were used to assess the severity of ADHD symptoms and chronotype preferences. Body mass index (BMI) was calculated and classified according to national age- and gender-specific reference values. The participants were divided into three groups as normal weight (<85%, n = 38), overweight (85%-95%, n = 30) and obesity (>95%, n = 42) according to their BMI percentile. There were statistically significant differences between the three groups in terms of chronotype preference (p = .000). Morningness preference was 86.84% in the normal BMI group and 26.19% in the obese BMI group. Eveningness preference was 7.89% in the normal BMI group and 61.90% in the obese BMI group. There was a correlation between the BMI percentile scores and the morningness/eveningness scale (M/E) scores. Moreover, there was a correlation between the BMI percentile scores and the oppositional and ADHD index scores. According to logistic regression analysis, the odds ratio of having evening type for obesity was 5.66 and the odds ratio of having morning type for normal weight was 13.03. Independently from ADHD symptoms, eveningness was directly related to obesity and morningness was directly related to normal weight. Prospective studies should be performed to better understand the relationship between ADHD, overweight/obesity and chronotype.     

A modified locally weighted method for developing reference standards for height, weight, and body mass index of boys and girls aged 4 to 18 in Taiwan

The objectives of this study are to modify the locally weighted method to obtain reference values for height, weight, and body mass indices (BMI): to describe the median growth velocity of children aged 4 to 18 in Taiwan; and to compare those values with data from other countries. We modified the LOCAL method to generate empirical percentiles and used the locally weighed regression to smooth the percentiles. We examined the smoothed percentiles against original data to ensure that smoothed percentiles were within 1% of errors. We used numerical differentiation of the 50th percentiles of height and weight to obtain the velocity of growth in height and weight, respectively. We applied our method to the data of the Nutrition and Health Survey in Taiwan, 1993-1996, which was a multistaged stratified sample. The sample included 2351 boys and 2355 girls aged 4 to 18. Our results indicate that (a) the proposed method, which utilizes the original data, guarantees the percentiles within 1% errors; (b) before puberty, the height, weight, and BMI of Taiwanese children are not much different from those of their counterparts in Western countries; and (c) after puberty and at the stage of young adulthood, the height, weight, and BMI of Taiwanese youth are below the levels of those in Western young adults. Genetic makeup and dietary patterns may contribute to these phenomena.     

Long-term changes in body weight, BMI, and adiposity rebound among children and adolescents in the Czech republic

The Czech Republic has undergone rapid political, social, and economic transformation since the late 1980s. While obesity rates among children and adolescents in the Czech Republic have been previously relatively low, this has changed in recent years. Across the past 50 years, body weight, body mass index (BMI)-for-age, and adiposity rebound (AR) (the time when a child reaches the lowest BMI before their BMI gradually begins to increase until adulthood) occurs earlier. The most dramatic changes have been observed among school-aged children, where BMI values have increased at the 50th, 90th, and 97th percentiles. In contrast, adolescent girls appear to be thinner than in the past. The analyses of weight-for-height percentiles indicated that the 50th percentile of the body weight among boys and girls remained similar in nearly all age categories across the past 50 years. Although the growth pattern of children at the 50th percentile has not changed, the 10th and 90th percentiles have expanded. Our findings suggest that the secular trend of increased height, accelerated growth, and earlier maturation is responsible for Czech children experiencing adiposity rebound at earlier ages compared to the past.     

Energy Intake and Meal Portions: Associations with BMI Percentile in U.S. Children

Objective: We examined relationships of eating patterns and reported energy intake (rEI) with BMI percentile in U.S. children. Research Methods and Procedures: Two 24‐hour dietary recalls from the Continuing Surveys of Food Intakes by Individuals 1994 to 1996 and 1998 (1005 boys, 990 girls) were averaged, and children were categorized into three age groups: 3 to 5 years (n = 1077), 6 to 11 years (n = 537), and 12 to 19 years (n = 381). Physiologically implausible reports due to reporting bias or abnormal intake (rEI outside ±18% to 23% of predicted energy requirements; pER) were identified. Results: rEI averaged 109 ± 34% and 100 ± 10% of pER in the total and plausible samples, respectively. EI was overreported more in younger children and underreported more in overweight older children. Children with plausible rEI (45.3% of sample) averaged 4.7 eating occasions/d, 589 kcal/meal, 223 kcal/snack, and 2038 kcal/d. rEI was not associated with BMI percentile in the total sample. In the plausible sample, rEI, meal portion size, and meal energy were positively associated with BMI percentile in boys 6 to 11 years and in children 12 to 19 years. No relationships were found in children 3 to 5 years and girls 6 to 11 years. Relationships were more consistent and stronger in the plausible compared with the total sample. Discussion: Excluding implausible dietary reports may be necessary for discerning dietary associations with BMI percentile. EI and meal, but not snack, patterns may play a quantitatively greater role in weight regulation as children age.     

Obesity and Sugar‐sweetened Beverages in African‐American Preschool Children: A Longitudinal Study

A representative sample of 365 low‐income African‐American preschool children aged 3–5 years was studied to determine the association between sugar‐sweetened beverage consumption (soda, fruit drinks, and both combined) and overweight and obesity. Children were examined at a dental clinic in 2002–2003 and again after 2 years. Dietary information was collected using the Block Kids Food Frequency Questionnaire. A BMI score was computed from recorded height and weight. Overweight and obesity were defined by national reference age‐sex specific BMI: those with an age‐sex specific BMI ≥85th, but <95th percentile as overweight and those with BMI ≥95th age‐sex specific percentile as obese. The prevalence of overweight was 12.9% in baseline, and increased to 18.7% after 2 years. The prevalence of obesity increased from 10.3 to 20.4% during the same period. Baseline intake of soda and all sugar‐sweetened beverages were positively associated with baseline BMI z‐scores. After adjusting for covariates, additional intake of fruit drinks and all sugar‐sweetened beverages at baseline showed significantly higher odds of incidence of overweight over 2 years. Among a longitudinal cohort of African‐American preschool children, high consumption of sugar‐sweetened beverages was significantly associated with an increased risk for obesity.     

Parental recognition of overweight in school-age children

Objective: Examine the accuracy of parental weight perceptions of overweight children before and after the implementation of childhood obesity legislation that included BMI screening and feedback. Methods and Procedures: Statewide telephone surveys of parents of overweight (BMI ≥ 85th percentile) Arkansas public school children before (n = 1,551; 15% African American) and after (n = 2,508; 15% African American) policy implementation were examined for correspondence between parental perception of child's weight and objective classification. Results: Most (60%) parents of overweight children underestimated weight at baseline. Parents of younger children were significantly more likely to underestimate (65%) than parents of adolescents (51%). Overweight parents were not more likely to underestimate, nor was inaccuracy associated with parental education or socioeconomic status. African‐American parents were twice as likely to underestimate as whites. One year after BMI screening and feedback was implemented, the accuracy of classification of overweight children improved (53% underestimation). African‐American parents had significantly greater improvements than white parents (P < 0.0001). Discussion: Parental recognition of childhood overweight may be improved with BMI screening and feedback, and African‐American parents may specifically benefit. Nonetheless, underestimation of overweight is common and may have implications for public health interventions.     

Height and Adiposity among Children

Objectives : Although BMI (kilograms per meter squared) is widely used as a surrogate measure of adiposity, it is moderately associated (r ～ 0.3) with height among children. We examined whether the resulting preferential classification of taller children as overweight, based on a BMI ≥95th percentile, is appropriate. Research Methods and Procedures : We assessed the cross‐sectional relation of height among 5‐ to 18‐year‐old subjects (n = 1180) to levels of BMI, the sum of 10 skinfold thicknesses, and percentage body fat as determined by DXA. Results : The prevalence of a BMI level ≥95th percentile was substantially higher among 5‐ to 11‐year‐old subjects who were relatively tall for their age than among shorter children. Among 5‐ to 8‐year‐old boys, for example, each SD increase in height‐for‐age was associated with a 4.6‐fold increase in the prevalence of overweight (p < 0.001). Height not only was associated with BMI but also showed similar correlations with the skinfold sum and with percentage body fat; furthermore, the magnitudes of these associations decreased with age. We also found that the association between percentage body fat and BMI (r = 0.85 to 0.90) was close to the maximum correlation that can be achieved by any weight‐height index. Discussion : The use of BMI, which preferentially classifies taller young children as overweight, is appropriate because height and adiposity are correlated before the age of 12 years.     

Asthma and Maternal Body Mass Index Are Related to Pediatric Body Mass Index and Obesity: Results from the Third National Health and Nutrition Examination Survey

Objective: Clinical research has shown an increased prevalence of obesity in children with asthma. This study was designed to assess the relationship between asthma and pediatric body mass index (BMI) in a national database and to examine factors that may modify this relationship. Design: The cross‐sectional relationship between asthma and pediatric BMI and obesity (BMI ≥ 85th percentile) was studied. Variables that may influence the relationship between asthma and pediatric BMI, such as race/ethnicity and television watching were included in the model for the total sample. A smaller sample of 3009 white and African American youth were studied in regression models including maternal BMI. Study Population: A nationally representative crosssectional sample of 5154 children and adolescents of 6 to 16 years of age from the Third National Health And Nutrition Examination Survey. Results: In the full sample, asthma and television watching were related to BMI, accounting for 3% of the variance in BMI. When maternal BMI was included in the nonHispanic sample, television watching, maternal BMI, and the interaction of maternal BMI and asthma were related to youth BMI, accounting for 15% of the variance. The standardized BMI z‐score for those youth without asthma and no maternal obesity was 0.06, which increased to 0.33 if the youth had asthma, to 0.70 if the youth did not have asthma but the mother was obese, and to 1.71 if the youth had asthma and the mother was obese. Asthma, television watching, and maternal BMI were independent predictors of youth obesity. Conclusions: BMI and prevalence of obesity is higher in youth with asthma. Pediatric BMI, but not obesity, is also related to the interaction of asthma and maternal BMI in white and African American youth. Comorbidity of asthma and obesity may complicate treatment of either condition, and prevention of obesity should be encouraged for asthmatic children.     

The intergenerational transmission of BMI in China

Based on the China Health and Nutrition Survey longitudinal data from 1989 to 2009 and using BMI z-score as the measure of adiposity, we estimate the intergenerational transmission of BMI in China. The OLS estimates suggest that a one standard deviation increase in father's or mother's BMI is associated with an increase of around 20% in child's Body Mass Index (BMI) z-score. These estimates decrease to around 14% when we control for family fixed effects. We examine the heterogeneity of this BMI intergenerational transmission process across family income, parental occupation and poverty status and also find this intergenerational correlation tends to be higher among children of higher BMI levels, though this tendency becomes weaker as children approach adulthood.     

Risk factors for obesity: further evidence for stronger effects on overweight children and adolescents compared to normal-weight subjects

Background

We recently showed that in preschoolers risk factors for overweight show stronger associations with BMI in children with high BMI values. However, it is unclear whether these findings might also pertain to adolescents.

Methods

We extracted data on 3–10 year-old (n = 7,237) and 11–17 year-old (n = 5,986) children from a representative cross-sectional German health survey (KiGGS) conducted between 2003 and 2006 and calculated quantile regression models for each age group. We used z-scores of children''s body mass index (BMI) as outcome variable and maternal BMI, maternal smoking in pregnancy, low parental socioeconomic status, exclusive formula-feeding and high TV viewing time as explanatory variables.

Results

In both age groups, the estimated effects of all risk factors except formula-feeding on BMI z-score were greatest for children with the highest BMI z-score. The median BMI z-score of 11–17 year-old children with high TV viewing time, for example, was 0.11 [95% CI: 0.03, 0.19] units higher than the median BMI z-score of teenage children with low TV viewing time. This risk factor was associated with an average difference of 0.18 [0.06, 0.30] units at the 90^th percentile of BMI z-score and of 0.20 [0.07, 0.33] units at the 97^th percentile.

Conclusions

We confirmed that risk factors for childhood overweight are associated with greater shifts in the upper parts of the children''s BMI distribution than in the middle and lower parts. These findings pertain also to teenagers and might possibly help to explain the secular shift in the upper BMI percentiles in children and adolescents.