David Boniface

Trends in physical activity and sedentary behaviour in adolescence: ethnic and socioeconomic differences.

Objective: To assess developmental trends in physical activity and sedentary behaviour in British adolescents in relation to sex, ethnicity and socioeconomic status (SES). Design: A 5-year longitudinal study of a diverse cohort of students aged 11–12 years at baseline in 1999. Setting: 36 London schools sampled using a stratified random sampling procedure. Participants: A total of 5863 students categorised as white, black or Asian, and stratified for SES using the Townsend Index. Main outcome measures: Number of days per week of vigorous activity leading to sweating and breathing hard. Hours of sedentary behaviour, including watching television and playing video games. Data were analysed using multilevel, linear, mixed models. Results: Marked reductions in physical activity and increases in sedentary behaviour were noticed between ages 11–12 and 15–16 years. Boys were more active than girls, and the decline in physical activity was greater in girls (46% reduction) than in boys (23%). Asian students were less active than whites, and this was also true of black girls but not boys. Black students were more sedentary than white students. Levels of sedentary behaviour were greater in respondents from lower SES. Most differences between ethnic and SES groups were present at age 11 years, and did not evolve over the teenage years. Conclusions: Physical activity declines and sedentary behaviour becomes more common during adolescence. Ethnic and SES differences are observed in physical activity and sedentary behaviour in British youth that anticipate adult variations in adiposity and cardiovascular disease risk. These are largely established by age 11–12 years, so reversing these patterns requires earlier intervention.

Development of adiposity in adolescence: five year longitudinal study of an ethnically and socioeconomically diverse sample of young people in Britain

Abstract Objective To examine the developmental trajectory of obesity in adolescence in relation to sex, ethnicity, and socioeconomic status. Design Five year longitudinal cohort study of a socioeconomically and ethnically diverse sample of school students aged 11-12 years at baseline. Setting 36 London schools recruited to the study in 1999 by a stratified random sampling procedure. Participants 5863 students participated in one or more years. Main outcome measures Weight, height, and waist circumference measured annually by trained researchers; overweight and obesity defined according to International Obesity Task Force criteria; adiposity and central adiposity indexed by body mass index (BMI) and waist standard deviation scores relative to 1990 British reference values. Results In school year 7 (age 11-12), the prevalence of overweight and obesity combined was almost 25%, with higher rates in girls (29%) and students from lower socioeconomic backgrounds (31%) and the highest rates in black girls (38%). Prevalence of obesity increased over the five years of the study at the expense of overweight, but no reduction occurred in the proportion of students with BMIs in the healthy range. Waist circumferences were high compared with 1990 norms at age 11 (by 0.79 SD in boys and by 1.15 SD in girls) and increased further over time. Both BMI and waist circumference tracked strongly over the five years. Conclusions Prevalence of overweight and obesity was high in London school students, with significant socioeconomic and ethnic inequalities. Little evidence was found of new cases of overweight or obesity emerging over adolescence, but few obese or overweight adolescents reduced to a healthy weight. The results indicate that persistent obesity is established before age 11 and highlight the need to target efforts to prevent obesity in the early years.

Comparing maternal and paternal intergenerational transmission of obesity risk in a large population-based sample

BACKGROUND Previous research showed childhood obesity to be more strongly associated with maternal weight than with paternal weight. However, confidence in this finding is limited by the lack of objectively measured data from both parents. OBJECTIVE We quantified the individual and combined effects of maternal and paternal overweight/obesity on obesity risk in children. DESIGN Data were pooled from the annual Health Surveys for England carried out between 2001 and 2006. Families with < or =2 children aged 2-15 y with anthropometric data available for both parents and children were included (n = 4432 families, n = 7078 children). Weights and heights were measured by a trained nurse. RESULTS Having 2 overweight parents was associated with an increased risk of child obesity [odds ratio (OR): 2.2; 95% CI: 1.3, 3.7; P < 0.001] compared with having 2 normal-weight parents. Having 2 obese (including severely obese) parents was associated with a higher risk of child obesity (OR: 12.0; 95% CI: 7.2, 20.1; P < 0.01), and having 2 severely obese parents was associated with an even higher risk of child obesity (OR: 22.3; 95% CI: 10.3, 48.4; P < 0.01) independent of age, sex, socioeconomic status, and ethnicity. Mother-child associations (r = 0.27) for body mass index were significantly stronger than father-child associations (r = 0.23), even after adjustment for plausible levels (< or =4%) of undisclosed nonpaternity. Associations were the same for sons and daughters but increased with age. CONCLUSIONS There is a strong and graded association between parental weight status and risk of childhood obesity, which is significantly stronger for maternal weight. Parental obesity could be used to target preventive interventions in the preschool years to avoid serious adverse effects on the future health of children.

Eating rate is a heritable phenotype related to weight in children

BACKGROUND There is growing interest in the heritability of behavioral phenotypes related to adiposity. One potential candidate is the speed of eating, although existing evidence for an association with weight is mixed. OBJECTIVE We aimed to assess the speed of eating in a sample of 10-12-y-old children to test the hypotheses that higher eating rate is related to greater adiposity and that eating rate is a heritable characteristic. DESIGN Video data of 254 twin children eating a standard meal at home were used to record eating rate (bites/min) and changes in eating rate across the 4 quarters of the meal. Adiposity was indexed with body mass index SD scores relative to British 1990 norms; for some analyses, children were categorized into groups of overweight or obese and into 2 subgroups of normal-weight (lower normal-weight or higher normal-weight) for comparison of the eating rate within the normal range as well as between clinical and nonclinical groups. All analyses controlled for clustering in twin pairs. Heritability of eating rate was modeled by using standard twin methods. RESULTS There was a significant linear association across the 3 weight groups for eating rate (P = 0.010), and regression analyses showed that eating rate increased by 0.18 bites/min for each 1-unit increase in body mass index SD score (P = 0.005). The heritability of eating rate was high (0.62; 95% CI: 0.45, 0.74). There was no association between weight group and a change (ie, deceleration) in eating rate over the mealtime. CONCLUSION Faster eating appears to be a heritable behavioral phenotype related to higher weight.

Eating for Pleasure or Profit The Effect of Incentives on Children’s Enjoyment of Vegetables

Parents commonly use rewards to encourage children to eat healthfully, but this practice remains controversial because rewards are suspected of undermining children’s intrinsic motivation. A cluster-randomized trial examined children’s acceptance of a disliked vegetable over 12 daily taste exposures. These exposures were paired with a tangible reward, a social reward, or no reward, and the findings were compared with the results from a no-treatment control condition. Liking and intake of the vegetable were assessed in a free-choice consumption task at preintervention, postintervention, 1 month after intervention, and 3 months after intervention. Liking increased more in the three intervention conditions than in the control condition, and there were no significant differences between the intervention conditions. These effects were maintained at follow-up. Children in both reward conditions increased consumption, and these effects were maintained for 3 months; however, the effects of exposure with no reward became nonsignificant by 3 months. These results indicate that external rewards do not necessarily produce negative effects and may be useful in promoting healthful eating.

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.

Perceived stress and weight gain in adolescence: a longitudinal analysis.

Although perceived stress has been hypothesized to be a risk factor for obesity, epidemiological studies relating stress to weight gain have shown mixed results. We examined prospective associations between perceived stress and changes in waist circumference and BMI in a large study of adolescents. As part of the Health and Behaviour in Teenagers Study (HABITS), height, weight, and waist circumference were measured annually in 4,065 adolescents aged from 11 to 16. Waist and BMI standard deviation scores (SDS) were used as indices of adiposity. Adolescents completed a measure of perceived stress each year, from which mean stress scores over the 5‐year period were also calculated and divided by tertile into lower, moderate, and higher stress. Associations between perceived stress at each year and adiposity 1–4 years later and also adiposity trajectories over the whole period in relation to mean stress were investigated. Analyses were adjusted for age, sex, ethnicity, socioeconomic deprivation, pubertal timing, and smoking. Perceived stress in any year was not related prospectively to increases in waist or BMI SDS 1–4 years later, nor was there any evidence that higher stress over the whole period was associated with greater gains in waist or BMI SDS. However, waist and BMI SDS were significantly higher in the moderate‐ and higher‐stress groups than the lower‐stress group across the whole 5‐year period. Persistent stress was associated with higher waist circumference and BMI in adolescence, but did not lead to differential changes over 5 years.

Appetite and Growth: A Longitudinal Sibling Analysis

IMPORTANCE Identifying early markers of future obesity risk can help target preventive interventions. Several studies have shown that a heartier appetite in infancy is a risk factor for more rapid weight gain, but to date no investigations have been able to rule out familial confounding. OBJECTIVES To use a sibling design (data from same-sex, dizygotic twin pairs) to test the hypothesis that sibling differences in infant appetite predicted differential weight gain during childhood. DESIGN, SETTING, AND PARTICIPANTS Gemini is a population-based twin cohort among the general United Kingdom population born between March 1, 2007, and December 15, 2007. Growth trajectories were analyzed from birth to age 15 months. Appetite-discordant pairs were selected from 800 nonidentical, same-sex twin pairs. EXPOSURES Appetite during the first 3 months of life was assessed with the food responsiveness (FR) and satiety responsiveness (SR) subscales from the Baby Eating Behaviour Questionnaire. Discordance was defined as a within-pair difference of at least 1 SD. MAIN OUTCOMES AND MEASURES A mean of 11.5 weight measurements per child were available between birth and age 15 months. Multilevel models, adjusted for sex and birth weight, compared growth curves for the higher-appetite vs lower-appetite twins. RESULTS In total, 172 pairs were discordant for SR and 121 pairs for FR. Within-pair analyses showed that those with higher FR and those with lower SR grew faster than their sibling. At age 6 months, those with higher FR were 654 (95% CI, 395-913) g heavier and at age 15 months were 991 (95% CI, 484-1498) g heavier. For sibling pairs discordant for SR, the weight differences between siblings were 637 (95% CI, 438-836) g at age 6 months and 918 (95% CI, 569-1267) g at age 15 months. CONCLUSIONS AND RELEVANCE A heartier appetite (indexed with higher FR or lower SR) in early infancy is prospectively associated with more rapid growth up to age 15 months in a design controlling for potential familial confounding, supporting a causal role for appetite in childhood weight gain. Appetite could be an early marker for risk of weight gain in the current obesogenic environment and might be a potential target for preventive interventions.

An international measure of awareness and beliefs about cancer: development and testing of the ABC

Objectives To develop an internationally validated measure of cancer awareness and beliefs; the awareness and beliefs about cancer (ABC) measure. Design and setting Items modified from existing measures were assessed by a working group in six countries (Australia, Canada, Denmark, Norway, Sweden and the UK). Validation studies were completed in the UK, and cross-sectional surveys of the general population were carried out in the six participating countries. Participants Testing in UK English included cognitive interviewing for face validity (N=10), calculation of content validity indexes (six assessors), and assessment of test–retest reliability (N=97). Conceptual and cultural equivalence of modified (Canadian and Australian) and translated (Danish, Norwegian, Swedish and Canadian French) ABC versions were tested quantitatively for equivalence of meaning (≥4 assessors per country) and in bilingual cognitive interviews (three interviews per translation). Response patterns were assessed in surveys of adults aged 50+ years (N≥2000) in each country. Main outcomes Psychometric properties were evaluated through tests of validity and reliability, conceptual and cultural equivalence and systematic item analysis. Test–retest reliability used weighted-κ and intraclass correlations. Construction and validation of aggregate scores was by factor analysis for (1) beliefs about cancer outcomes, (2) beliefs about barriers to symptomatic presentation, and item summation for (3) awareness of cancer symptoms and (4) awareness of cancer risk factors. Results The English ABC had acceptable test–retest reliability and content validity. International assessments of equivalence identified a small number of items where wording needed adjustment. Survey response patterns showed that items performed well in terms of difficulty and discrimination across countries except for awareness of cancer outcomes in Australia. Aggregate scores had consistent factor structures across countries. Conclusions The ABC is a reliable and valid international measure of cancer awareness and beliefs. The methods used to validate and harmonise the ABC may serve as a methodological guide in international survey research.

The Intergenerational Transmission of Thinness

OBJECTIVES To examine intergenerational associations for thinness and to compare maternal and paternal effects. DESIGN Population-based, cross-sectional design using data from the Health Survey for England from January 1, 2001, through December 31, 2006. SETTING The Health Survey for England, an annual, national survey representative of the population living in private households in England. PARTICIPANTS Families with children and adolescents aged 2 to 15 years with anthropometric data available for children and adolescents and 2 parents (N = 4423 families, N = 7078 children and adolescents). MAIN EXPOSURE Trained interviewers collected height and weight measurements. MAIN OUTCOME MEASURE Child/adolescent thinness, categorized using International Obesity Task Force criteria. RESULTS Of 7078 children and adolescents, 402 (5.7%) were categorized as being thin. Thinness was more common in 2- to 5-year-olds (odds ratio, 1.61; 95% confidence interval, 1.22-2.13) than in 11- to 15-year-olds and in children and adolescents from ethnic minority (black: 2.28; 1.22-4.26; and Asian: 3.65; 2.76-4.83) than white backgrounds, but no differences were observed by sex or socioeconomic status. The strongest predictor of child/adolescent thinness was parental weight status. The prevalence of thinness was highest (16.2%) when both parents were thinner and progressively lower when both parents were in the upper half of the healthy-weight range (7.8%) or were overweight (5.3%) or obese (2.5%), with no differences in the magnitude of maternal and paternal influences. CONCLUSIONS These results are consistent with the idea that many cases of thinness are likely to represent the low end of the healthy distribution of weight and, as such, are likely to have a primarily genetic origin.