Claire Hill

Adiposity and 'eating in the absence of hunger' in children.

Objective:To examine the association between eating in the absence of hunger (EAH) and adiposity in children.Design:Two cross-sectional studies in community settings.Subjects:For study 1, 348 children (178 girls and 170 boys) aged 7–9 years were recruited as part of the Physical Exercise and Appetite in Children Study. In study 2, participants were a subsample of children aged 9–12 years (N=316; 192 girls and 124 boys) from the Twins Early Development Study.Measurements:EAH was operationalized as intake of highly palatable sweet snacks after a mixed meal at school (study 1) or home (study 2). Weight (kg) and height (m) measurements were used to calculate the body mass index (BMI) s.d. scores. Children were grouped using the standard criteria for underweight, healthy weight, overweight and obesity. The healthy weight range was further subdivided into lower healthy weight (⩽50th centile) and higher healthy weight (>50th centile) to examine the distribution of EAH across the adiposity continuum.Results:In both studies, EAH showed a significant positive association with adiposity in boys after adjusting for covariates (P<0.001), with a linear increase in the intake across underweight, healthy weight and overweight groups. The association between EAH and adiposity was not significant in girls in either study, although in study 1, results showed a quadratic trend, with EAH increasing through the underweight and healthy weight ranges and decreasing in overweight and obese groups.Conclusion:EAH is a behavioural phenotype that is not specific to overweight children but instead shows a graded association with adiposity across the weight continuum, particularly in boys. In this study, the effect was less pronounced in girls, which may reflect social desirability pressures constraining food intake among heavier girls.

The relative reinforcing value of food predicts weight gain in a longitudinal study of 7–10-y-old children

BACKGROUND The relative reinforcing value (RRV) of food, defined as how hard an individual is prepared to work to gain access to food rather than a nonfood alternative, has been shown to be higher in obese adults and children than in their normal-weight counterparts. However, these cross-sectional studies are unable to determine whether a high RRV of food is predictive of adiposity change or whether it is a consequence of being obese. OBJECTIVE The objective was to examine the association between the RRV of food and 1-y weight gain in children aged 7-10 y. DESIGN An observational longitudinal study design was used. The RRV of food was determined by using a questionnaire method at baseline when the children (n = 316) were aged 7-9 y. Adiposity [body mass index (BMI), BMI SD score, fat mass index, waist circumference, and waist circumference SD score] was assessed at baseline and after 1 y. RESULTS Regression analyses indicated that the RRV of food was not associated with any measure of adiposity at baseline or at the 1-y follow-up (all P > 0.58). Changes in BMI (B = 0.06, P < 0.001), BMI SD score (B = 0.03, P = 0.001), and fat mass index (B = 0.09, P = 0.001) after 1 y were significantly predicted by the RRV of food at baseline. CONCLUSIONS The RRV of food predicted the change in adiposity over a relatively short-term period of 1 y and thus may be associated with the development of obesity. The lack of association in cross-sectional analyses indicates that this behavior is a risk factor for weight gain, although weight differences may not emerge until later childhood.

Differences in physical activity and sedentary time in relation to weight in 8-9 year old children.

BackgroundThe health benefits of physical activity for children are well established. Although objective measures of physical activity are increasingly used there is still a lack of adequate data on physical activity in children. Sex differences in physical activity have been consistently demonstrated and lower levels of physical activity in obese than non-obese children have been shown. However, differences across the whole weight spectrum have not been examined in detail. The aim of this study was to assess associations between physical activity and sedentary time across the weight spectrum in children, and to determine whether the associations differed by sex.MethodsParticipants in the current study were 176 boys and 169 girls aged 8–9 years old taking part in a longitudinal study of associations between eating behaviours, physical activity and weight gain during childhood. Height, weight and waist circumference were measured, and physical activity data were collected using an Actigraph model GT1M worn for 5 consecutive days. Associations between sex, weight and physical activity were analysed using linear regression models.ResultsBoys had higher total activity (mean difference = 119, p < 0.001) and more minutes of moderate and vigorous physical activity (MVPA) (mean difference = 25, p < 0.001) than girls. A higher percentage of boys (72%) than girls (30%) met current physical activity guidelines of 60 minutes MVPA per day. In boys, weight status significantly predicted total activity (p = 0.001) and MVPA (p = 0.001) but there were no significant associations in girls. There was no significant difference in time spent sedentary between boys and girls, and weight status did not predict sedentary time.ConclusionIn boys, physical activity was progressively lower across the weight spectrum, but in girls physical activity was consistently low across all weight categories. Intervention is required prior to 8 years old to prevent weight-related declines in physical activity in boys and further research is required to determine at what age, if ever, weight related differences in physical activity are apparent in girls.

Weight status and perceived body size in children

Objective: To investigate associations between weight status and body size perception in children in the UK. Design: Cross-sectional survey. Setting: School-based sample in the UK. Participants: 399 children (205 boys, 194 girls) aged 7–9 years. Main outcome measures: Perceived body size was assessed using a visual method (Childrens Body Image Scale, matching to images representing body mass indexes (BMI) from 3rd to 97th percentiles) and verbal descriptors from ”too thin„ to ”too fat„. BMI (converted to BMI SD scores using UK data) was assessed and demographic information was recorded. Results: Modest associations between actual and perceived body size were found with visual (r  =  0.43, p<0.001) and verbal (r  =  0.41, p<0.001) methods, but there was a consistent response bias towards underestimation. Using visual matching, most children (45%) underestimated their body size, with significantly greater underestimation (p<0.001) at higher BMI. A gender-by-weight group interaction (p = 0.001) showed that at lower weights girls were more accurate than boys, but at higher weights girls were less accurate. Using the verbal scale, the majority of children reported their body size as “just right” in all weight groups (52–73%), with no sex differences. Conclusions: Children can estimate their body size using visual or verbal methods with some accuracy, but show greater underestimation at higher weights, especially in girls. These findings suggest that underestimation is more widespread than has been assumed, which has implications for health education among school-aged children.

MVPA Is Associated with Lower Weight Gain in 8–10 Year Old Children: A Prospective Study with 1 Year Follow-Up

Background Studies relating physical activity (PA) to weight gain in children have produced mixed results, although there is some evidence for stronger associations with more intense physical activities. The present study tested the hypothesis that weight gain over one year in 8–10 year olds would be more strongly predicted by moderate and vigorous physical activity (MVPA) than total physical activity (total PA) or sedentary behaviour. Methodology Participants were 280 children taking part in the Physical Exercise and Appetite in Children Study (PEACHES). Weight status was assessed using body mass index (BMI), fat mass index (FMI), and waist circumference (WC) in school Year 4 (baseline; age 8.7 yrs) and Year 5 (follow-up; age 9.7 yrs). Physical activity was measured at baseline using the Actigraph GT1M accelerometer to assess total PA (mean accelerometers counts per minute), MVPA; ≥4000 counts per minute) and sedentary time (<100 counts per minute). Principal Findings After adjustment for baseline BMI, SES, sex and ethnicity, MVPA was significantly associated with follow–up BMI (adjusted β = −0.07; p = 0.002). This association was independent of total PA or sedentary time. Similar results were observed for FMI; again MVPA was significantly associated with follow up FMI (β = −0.16; p = 0.001) independent of total PA or sedentary time. The pattern was similar for WC (β = −0.07), but the association between MVPA and WC did not reach significance at p = 0.06. Conclusion The results of this study strongly support promotion of MVPA in children.

Psychosocial correlates of objectively measured physical activity in children

BACKGROUND A large proportion of UK children do not reach the recommended levels of physical activity (PA) required for optimum health. Few studies have investigated the psychosocial correlates of objectively measured PA in preadolescents. This study examined child attitudes and parental behaviours as correlates of childrens activity. METHODS In total, 278 children (138 boys and 140 girls) aged 7-9 years were recruited as part of the Physical Exercise and Appetite in Children Study (PEACHES). Activity was objectively measured using the Actigraph GT1M accelerometer; the variables were total PA (mean accelerometer counts min(-1)) and moderate and vigorous PA (MVPA) >2000 counts min(-1). Child-focussed variables were self-efficacy (Physical Activity Self-Efficacy scale), physical performance self-concept (Self-Perception Profile for Children), positive and negative outcome expectancies and liking for PA. Parental variables were PA and support for child activity. RESULTS Significant sex-by-psychosocial outcome interactions were observed for total PA and MVPA, so data from boys and girls were analysed separately. No psychosocial or parental outcomes were correlated with activity in girls. Significant correlates of activity in boys (self-efficacy, self-concept and parental support) were entered in to a hierarchical regression using both total PA and MVPA and, controlling for BMI SD, SES and ethnicity. PA self-efficacy and self-concept were significantly independently associated with total PA, explaining around 12% of the variance. Self-efficacy was significantly associated with time spent in MVPA, also explaining around 12% of the variance in this behaviour. Parental support was not significant in the regression model. CONCLUSION PA self-efficacy and self-concept are significant correlates of objectively measured PA in UK boys.

Adiposity is not associated with children's reported liking for selected foods

It is often assumed that heightened liking for energy-dense foods contributes to the development of obesity, however previous findings on the association between adiposity and liking among common foods are inconclusive in adults and there is limited research in children. Therefore the present study assessed the association between adiposity and liking for fatty or sugary foods, fruits and vegetables in children. A community sample of children aged 7-9 years (N=366) were recruited as part of the Physical Exercise and Appetite in CHildren Study (PEACHES). Anthropometric measurements (BMI- and waist-SD scores, fat mass index) were taken alongside self-reported liking for a list of fatty or sugary foods, fruits and vegetables. Regression analyses were used to predict liking from continuous adiposity measures (BMI- and waist-SD score, fat mass index). Linear trend analysis was used to assess the patterning of liking across weight categories. Vegetables were liked less than fatty or sugary foods or fruit, but there was no difference between liking for fruit and for fatty or sugary foods. Boys had a higher liking for fatty or sugary foods than girls, although sex-by-adiposity interactions were not significant for any of the food categories. There was no association between liking for any of the food categories and adiposity. This suggests that overweight in children is not reflective of differences in liking for selected common foods. Variation in appetitive responsiveness to food with increasing adiposity may be more salient in the development of obesity.

Emergence and Persistence of Overweight and Obesity in 7- to 11-Year-Old Children

Aim: After dramatic rises in paediatric obesity, the critical period for obesity onset may now be pre-adolescence. Methods: We monitored adiposity over 4 years in 400 children aged 7-9 years recruited from schools in London. Weight, height, waist circumference (WC) and fat mass were measured annually. Weight status was defined using International Obesity Task Force (IOTF) criteria, and standardised scores and percentiles used British 1990 reference data. Results: BMI, WC and fat mass index all tracked strongly over time (average correlation for BMI = 0.95). Emergence of obesity was relatively uncommon: only 2% of the total sample increased from overweight to obese over the 4-year period, and this was nearly matched by the 1.3% that reduced from obese to overweight. However, more children (6%) moved from healthy weight to overweight than the reverse direction (2%). There were greater absolute gains in adiposity in children with higher baseline weight status, but this was disguised in analyses using standardised scores. Obesity was not an emergent trait in middle childhood, but rates were already high and, in absolute terms, adiposity increased more in overweight and obese than healthy weight children. Conclusion: These results highlight the need for active management of obesity in middle childhood.