Associations between physical activity and fat mass in adolescents: the Stockholm Weight Development Study

Socioeconomic position and body composition in childhood in high- and middle-income countries: a systematic review and narrative synthesis

BACKGROUND

The relation between socioeconomic position (SEP) and obesity measured by body mass index (BMI), a measure of weight for height, has been extensively reviewed in children, showing consistent associations between disadvantaged SEP and higher BMI in high-income countries (HICs) and lower BMI in middle-income countries (MICs). Fat mass (FM), a more accurate measure of adiposity, and fat-free mass (FFM) are not captured by BMI, but have been shown to track from childhood to adulthood, and be important for cardiovascular health and functional outcomes in later life. It is not clear whether body composition is associated with SEP. We systematically reviewed the association between SEP and body composition in childhood.

METHODS

A systematic review was carried out following PRISMA guidelines. The protocol was pre-registered with PROSPERO (CRD42019119937). Original studies in the English language, which examined the association between SEP and body composition in childhood, were included. An electronic search of three databases was conducted. Two independent reviewers carried out screening, data extraction and quality assessment. Due to heterogeneity in results, a narrative synthesis was conducted. Heterogeneity in findings according to SEP, sex, body composition measure and country income level was investigated.

RESULTS

50 papers were included, the majority from HICs. No papers were from low-income countries. Disadvantage in childhood was associated with greater FM and lower FFM in HICs, but with lower FM and lower FFM in MICs. When measures of FFM indexed to height were used there was no evidence of associations with SEP. In HICs, more studies reported associations between disadvantaged SEP and higher FM among girls comparative to boys.

CONCLUSIONS

Inequalities in FM are evident in HICs and, in the opposite direction, in MICs and follow similar trends to inequalities for BMI. Inequalities in height are likely important in understanding inequalities in FFM.

Cognitive disinhibition and infrequent moderate-to-intense physical activity linked with obesity in U.S. soldiers

PURPOSE

To explore the relationship between body weight status and neurocognitive functioning in soldiers.

METHODS

U.S. soldiers (N = 109) answered survey questions and completed neurocognitive tests including simple reaction time, code substitution, procedural reaction time, go-no-go, matching to sample, code substitution recall, and four versions of the Stroop test including congruent (color and meaning of word agreed); incongruent (color and meaning of word differed); neutral (nonsense words appeared), and emotional (combat-related words such as "I.E.D" and "convoy" appeared). Self-reported heights and weights were used to calculate BMI. A BMI ≥ 30.00 kg/m² was categorized as obese. Multivariate analysis of variance was used to analyze weight status differences (p ≤ 0.05) across neurocognitive variables. Binomial logistic regression analysis with obesity as the dependent variable was used to ascertain the contributions (p ≤ 0.05) of exercise and the neurocognitive measures that differed based on weight status.

RESULTS

Twenty-nine participants (26.6%) were obese. The obese group had significantly lower scores on code substitution, and both neutral and emotional Stroop tasks. Only Stroop emotional scores, p = 0.022, OR = 0.97, and frequency of moderate/intense physical activity, p = 0.009, OR = 0.10, were significant predictors of weight status.

CONCLUSIONS

Obesity was associated with less frequent moderate/intense physical activity and compromised executive functioning, namely decrements in response inhibition. Given the design and sample size, additional research is needed to better understand the direction of the relationship between these variables and to inform research related to the treatment and prevention of obesity within military populations.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

Associations of serum leptin, ghrelin and peptide YY levels with physical activity and cardiorespiratory fitness in adolescent boys with different BMI values

The aim of this study was to investigate the differences in associations of serum acylated and des-acylated ghrelin, peptide YY (PYY) and leptin levels with physical activity (PA) and cardiorespiratory fitness (CReF) in adolescent boys (mean age of 14.0 years) with overweight (OWB; n=55) and with normal weight (NWB; n=154).

METHODS

Total PA was measured by 7-day accelerometry (counts/min) and CReF by peak oxygen consumption (VO²peak/kg).

RESULTS

No differences were found in serum PYY, acylated ghrelin or des-acyl ghrelin levels, whereas mean leptin (11.6±10.6 vs. 2.0±2.7 ng/ml; p<0.05) and insulin (18.1±8.7 vs. 11.0±6.2 mU/l; p<0.05) levels were significantly higher in OWB compared to NWB. Mean CReF was significantly lower in OWB compared to NWB (39.7±8.7 vs. 50.5±6.8 ml/min/kg; p<0.05). Leptin was negatively correlated with CReF in both groups (r=-0.43; p<0.05), des-acylated ghrelin with CReF only in OWB (r =-0.36; p<0.05). In OWB leptin was negatively correlated with total PA (r=-0.32; p<0.05) and positively with sedentary time of PA (r=0.35; p<0.05). In NWB 28.1% of the variability of CReF was determined by leptin and insulin resistance index (HOMA-IR), whereas in OWB 71.9% was determined by trunk FM and BMI.

CONCLUSIONS

Leptin concentration was inversely associated with CReF in adolescent boys independently of BMI in both groups, while des-acylated ghrelin was associated with CReF only in OWB. Low PA in OWB was associated with high serum leptin level.

Socioeconomic position and childhood-adolescent weight status in rich countries: a systematic review, 1990-2013

Background

Childhood obesity is a major problem in rich countries due to its high prevalence and its harmful health consequences. An exploratory analysis conducted in the PubMed database highlighted that the number of papers published on the relationship between socioeconomic position (SEP) and childhood-adolescent weight status had risen substantially with respect to an earlier review which had covered the period 1990–2005.

Methods

To describe the findings on the relationship between SEP and childhood-adolescent weight status in papers published in rich countries from 1990 through 2013, studies were identified in the following databases: PubMed; Web of Knowledge (WOK); PsycINFO; Global Health; and Embase. We included observational studies from the 27 richest OECD countries, which covered study populations aged 0 to 21 years, and used parental education, income and/or occupation as family SEP indicators. A total of 158 papers met the inclusion criteria and reported 134 bivariable and 90 multivariable analyses.

Results

Examination of the results yielded by the bivariable analyses showed that 60.4 % of studies found an inverse relationship, 18.7 % of studies did not found relationship, and 20.9 % of studies found a relationship that varied depending on another variable, such as age, sex or ethnic group; the corresponding percentages in the multivariable analyses were 51.1, 20.0 and 27.8 %, respectively. Furthermore, 1.1 % found a positive relationship.

Conclusion

The relationship between SEP and childhood-adolescent weight status in rich countries is predominantly inverse and the positive relationship almost has disappeared. The SEP indicator that yields the highest proportion of inverse relationships is parents’ education. The proportion of inverse relationships is higher when the weight status is reported by parents instead using objective measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0443-3) contains supplementary material, which is available to authorized users.

School environment, socioeconomic status and weight of children in Bloemfontein, South Africa

BACKGROUND

The continued existence of undernutrition, associated with a steady increase in the prevalence of overweight and obesity in children and adolescents, necessitates identification of factors contributing to this double burden of disease, in order for effective treatment and prevention programmes to be planned.

AIM

To determine the nutritional status of 13-15-year-old children in Bloemfontein and its association with socioeconomic factors.

SETTING

Bloemfontein, Free State Province, South Africa (2006).

METHODS

This was a cross-sectional analytical study. Randomly selected children (n = 415) completed structured questionnaires on socioeconomic status. The children's weight and height were measured and body mass index-for-age and height-for-age z-scores were computed according to World Health Organization growth standards in order to determine the prevalence of underweight, overweight, obesity and stunting. Waist circumference was measured to classify the children as having a high or very high risk for metabolic disease.

RESULTS

Of the 415 children who consented to participate in the study, 14.9% were wasted and 3.4% were severely wasted. Only 6% of the children were overweight/obese. Significantly more boys (23.0%) were wasted than girls (10%) and severe stunting was also significantly higher in boys than in girls (10.3% and 4.2%, respectively). Children whose parents had graduate occupations were significantly more overweight/obese than those with parents working in skilled occupations. Stunting was significantly higher in low (31.4%) and medium (30.4%) socioeconomic groups compared to the high socioeconomic group (18.1%).

CONCLUSION

A coexistence of underweight and overweight was found and gender and parental occupation were identified as being predictors of nutritional status.

Lifestyle practices and obesity in Malaysian adolescents

Aim: To determine the influence of physical activity (PA) and sedentary behavior (SB) on obesity profiles of 454 Malaysian adolescents aged 12 to 19. Methods: Validated PA and SB questionnaires were used and body composition assessed using anthropometry and dual-energy X-ray absorptiometry (DXA). Results: Gender-specific multivariate analyses showed boys with high levels of total PA and moderate-to-vigorous physical activity (MVPA) exhibited significantly lower levels of total body fat, percent body fat and android fat mass compared with low PA and MVPA groups, after adjusting for potential confounders. Girls with high SB levels showed significantly higher BMI, waist circumference and DXA-derived body fat indices than those at lower SB level. Multiple logistic analyses indicated that boys with low levels of total PA and MVPA had significantly greater obesity risk, 3.0 (OR 3.0; 95% CI, 1.1–8.1; p < 0.05) and 3.8-fold (OR 3.8; 95% CI, 1.4–10.1; p < 0.01), respectively, than more active boys. Only in girls with high SB level was there a significantly increased risk of obesity, 2.9 times higher than girls at low SP levels (OR 2.8; 95% CI, 1.0–7.5; p < 0.05). Conclusions: The present findings indicate that higher PA duration and intensity reduced body fat and obesity risk while high screen-based sedentary behaviors significantly adversely influenced body fat mass, particularly amongst girls when the PA level was low.

The performance of obesity screening tools among young Thai adults

Obesity is a worldwide medical condition that leads to physical and psychological impairment. Specific ethnicity, gender and age group are related to different performances of anthropometric indices to predict obesity. The objectives of this study were to estimate the performance of the anthropometric indices for detecting obesity based on percentage of body fat (PBF), to study the correlation among those indices, and to determine the optimal cut-off point of the indices among young Thai adults. This is a cross-sectional study of healthy urban subjects in Khon Kaen, Thailand who were aged 20-39 years. Baseline characteristics and anthropometric measures were collected. PBF was determined using bioelectrical impedance analysis. Demographic data and anthropometric variables were analyzed using descriptive statistics. Receiver-operating characteristic (ROC) curves were used to compare the performance of anthropometric measures as predictors of obesity. One-hundred men and 100 women were recruited for this study. Body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-stature ratio (WSR) were significantly correlated to PBF. BMI demonstrated the best performance according to the area under the ROC curves in both sexes at cut-off points of 22.5 in women or 25 kg/m(2) in men. WC and WSR showed better performance than WHR to detect obesity. In conclusion, anthropometric indices in young Thai adults were correlated well with PBF to predict obesity as shown in prior reports. Different cut-off points of these indices to define obesity in young Thai adults are recommended. The global cut-off points of WSR in women regardless of ethnicity are supported.

Socioeconomic position across life and body composition in early old age: findings from a British birth cohort study

BACKGROUND

Previous studies have reported associations between lower lifetime socioeconomic position (SEP) and higher body mass index in adulthood, but few have examined associations with direct measures of fat and lean mass which are likely to have independent roles in health and physical functioning.

METHODS

We examined associations of SEP across life with dual-energy X-ray absorptiometry measures of fat and lean mass at 60-64 years using data from a total of 1558 men and women participating in the Medical Research Council (MRC) National Survey of Health and Development. We also examined whether associations of childhood SEP with fat and lean mass were explained by preadulthood weight gain (birth weight, 0-7 and 7-20 years) and adult SEP.

RESULTS

Lower SEP across life was associated with higher fat mass and higher android to gynoid fat mass ratio. For example, the mean difference in fat mass index comparing the lowest with the highest paternal occupational class at 4 years (slope index of inequality) was 1.04 kg/m(1.2) in men (95% CI 0.09 to 1.99) and 2.61 in women (1.34 to 3.89), equivalent to a 8.6% and 16.1% difference, respectively. After adjustment for fat mass, lower SEP across life was associated with lower lean mass in women, while only contemporaneous household income was associated in men. Associations between childhood SEP and outcomes were partly explained by preadulthood weight gain and adult SEP.

CONCLUSIONS

This study identified lifetime socioeconomic patterning of fat and lean mass in early old age. This is likely to have important implications and may partly explain socioeconomic inequalities in health and physical functioning.

Objectively measured patterns of physical activity in primary school children in Coventry: the influence of ethnicity

AIMS

The aetiology of increased metabolic risk in South Asians is incompletely understood, but may include modifiable factors such as physical activity. This study assessed patterns of physical activity in UK primary school children and examined the influence of ethnicity.

METHODS

We studied a community sample of children aged 8-9 years attending primary schools in Coventry, UK. One hundred and sixty-one children wore combined physical activity and heart rate monitors for 7 days. Levels of activity and energy expenditure were compared between White European (n = 96) and South Asian children (n = 65). Patterns of physical activity during the school week were also described.

RESULTS

Seventy-three per cent of White Europeans compared with only 35% of South Asians achieved international recommendations of 60 minutes of moderate to vigorous physical activity daily (P < 0.0000). South Asians were less active during the week (106 ± 28 vs. 120 ± 32 counts/min, respectively, P = 0.0054) and at weekends (92 ± 34 vs. 108 ± 54 counts/min, P = 0.0118) compared with White Europeans. There were differences in energy expenditure with lower physical activity levels in South Asians (daily average 1.68 ± 0.13 vs. 1.76 ± 0.17, P < 0.0001). Differences were attributable to less activity after school in South Asians (97 ± 29 vs. 120 ± 43 counts/min, P < 0.0000) as daytime activity was comparable between groups (120 ± 41 vs. 124 ± 39 counts/min, P > 0.05).

CONCLUSION

South Asian children in Coventry do significantly less physical activity than White Europeans, mainly attributable to differences in after-school activity. Ethnically tailored interventions should explore whether physical activity can be increased in South Asian children and, if so, whether this increased physical activity improves metabolic health.

Association between sedentary behaviour and socioeconomic factors, diet and lifestyle among the Balearic Islands adolescents

BACKGROUND

Many different factors influenced food habits and physical activity patterns of adolescents in a complex interactive way. The aim of this study was to assess association between sedentary behaviour and socioeconomic factors, diet and lifestyle among the Balearic Islands adolescents.

METHODS

A cross-sectional survey (n = 1961; 12-17 years old) was carried out. Physical activity was assessed using the International Physical Activity Questionnaire for adolescents (IPAQ-A). Sedentary behaviour was defined as <300 min/week of moderate and vigorous physical activity. Anthropometric measurements, body image, socio-economic and lifestyle determinants, food consumption, and adherence to the Mediterranean diet were assessed.

RESULTS

The prevalence of sedentary behaviour was 37.1% (22.0% boys, 50.8% girls). Active boys consumed frequently breakfast cereals and fresh fruit; active girls yogurt, cheese, breakfast cereals, and fresh fruit; and sedentary girls high fat foods and soft drinks. Sedentary behaviour of girls was directly associated to age, and time spent on media screen and homework, and inversely related to adherence to Mediterranean diet, and body composition. Sedentary behaviour of boys was inversely related to adherence to the Mediterranean diet, and the desire to remain the same weight.

CONCLUSIONS

The prevalence of sedentary behaviour among Balearic Islands adolescents is high, mainly among girls. Age, sex, parental educational and profession levels, body size dissatisfaction, and poor quality diet are important factors of physical activity practice among adolescents.

Inflammatory markers and metabolic syndrome among adolescents

BACKGROUND/OBJECTIVES

The alarming increase in obesity worldwide is of concern, owing to the associations of obesity with metabolic syndrome (MetS), which has been associated with a proinflammatory state characterized by elevated plasma concentrations of several markers of inflammation. The aim of this study was to assess levels of inflammatory markers and their association with MetS among adolescents.

SUBJECTS/METHODS

A random sample of adolescents (n=362, 143 boys and 219 girls, 12-17 years) was interviewed, anthropometrically measured and provided a fasting blood sample. Circulating levels of adiponectin, leptin, tumour necrosis factor-alpha, plasminogen activator inhibitor 1 (PAI-1), interleukin-6 and high-sensitivity C-reactive protein were measured. The association between inflammatory markers and sex, age, body mass index (BMI) status, MetS, physical activity and blood pressure was also calculated.

RESULTS

Adiponectin levels are inversely associated and leptin levels are directly associated with MetS and BMI, but directly with gender (females show higher levels than boys), and PAI-1 levels are directly associated with MetS, among adolescents.

CONCLUSIONS

Leptin, adiponectin and PAI-1 may be used as biomarkers to predict MetS among adolescents.

Prediction of childhood obesity by infancy weight gain: an individual-level meta-analysis

To assess the predictive ability of infant weight gain on subsequent obesity we performed a meta-analysis of individual-level data on 47,661 participants from 10 cohort studies from the UK, France, Finland, Sweden, the US and Seychelles. For each individual, weight SD scores at birth and age 1 year were calculated using the same external reference (British 1990). Childhood obesity was defined by International Obesity Task Force criteria. Each +1 unit increase in weight SD scores between 0 and 1 year conferred a twofold higher risk of childhood obesity (odds ratio = 1.97 [95% confidence interval (CI) 1.83, 2.12]), and a 23% higher risk of adult obesity (odds ratio = 1.23 [1.16, 1.30]), adjusted for sex, age and birthweight. There was little heterogeneity between studies. A risk score for childhood obesity comprising weight gain 0-1 year, mother's body mass index, birthweight and sex was generated in a random 50% selection of individuals from general population cohorts with available information (n = 8236); this score showed moderate predictive ability in the remaining 50% sample (area under receiving operating curve = 77% [95% CI 74, 80%]). A separate risk score for childhood overweight showed similar predictive ability (area under receiving operating curve = 76% [73, 79%]). In conclusion, infant weight gain showed a consistent positive association with subsequent obesity. A risk score combining birthweight and infant weight gain (or simply infant weight), together with mother's body mass index and sex may allow early stratification of infants at risk of childhood obesity.

Western and Mediterranean dietary patterns among Balearic Islands' adolescents: socio-economic and lifestyle determinants

OBJECTIVE

To assess prevailing food patterns among Balearic Islands' adolescents, and socio-economic and lifestyle determinants.

DESIGN

Cross-sectional nutritional survey carried out (2007-2008) in the Balearic Islands, a Mediterranean region. Dietary assessment was based on a 145-item semi-quantitative FFQ and two non-consecutive 24 h recalls. Anthropometric measurements and questions related to socio-economic, lifestyle, physical activity and body image were assessed.

SETTING

Data obtained from a representative sample of all inhabitants living in the Balearic Islands aged 12-17 years.

SUBJECTS

A random sample (n 1231) of the adolescent population (12-17 years old) was interviewed.

RESULTS

Factor analysis identified two major dietary food patterns: 'Western' and 'Mediterranean'. The 'Western' dietary pattern was higher among boys than girls, associated with spending ≥4 h/d on media screen time, but less prevalent among those adolescents who desired a thinner body and those girls who desired to remain the same weight. The 'Mediterranean' dietary pattern was mainly followed by girls, and also boys who spent < 2 h/d on media screen time and girls with high parental socio-economic status.

CONCLUSIONS

The present study shows the existence of two major dietary patterns among Balearic Islands' adolescents: 'Western' and 'Mediterranean', but girls are more 'Mediterranean' than boys. This evidence supports that the food pattern of Balearic Islands' adolescents is in a transitional state characterised by the loss of the traditional Mediterranean dietary pattern towards a Western dietary pattern. Low parental socio-economic status, much leisure-time on sedentary behaviours such as media screen time and body image are factors associated with the 'Western' dietary pattern.

Lifestyle and cardiovascular risk factors in 2001 child-parent pairs: the PEP Family Heart Study

OBJECTIVE

Genes and environment are the main determinants of cardiovascular disease (CVD) risk factor clustering in families. Since individual risk factor profiles are easily predicted within families, we examined whether CVD risk factors are affected by lifestyle factors in these families.

METHODS

Nutrition, physical activity, and smoking habits were assessed in 2001 biological child-parent pairs from 852 families participating in the Prevention Education Program (PEP). Height, weight, body mass index, waist circumference, blood pressure, and fasting lipid levels were measured. Within-family associations were calculated using generalized estimating equations (GEE).

RESULTS

Fathers possessed the most adverse risk profile. Daily energy consumption above the recommended levels was higher in children (daughters +35.4%, sons +26.7%) than in parents (fathers +15.7%, mothers +10.6%). Higher energy consumption was significantly associated with hypertension in mothers (OR 2.5) and in fathers (OR 1.7). Hyper-caloric nutrition of the parents predicted the energy intake of the children in: mother-daughter (OR 7.5), mother-son (OR 3.0), and father-son (OR 2.8) pairs. Low mono-unsaturated fatty acid intake was significantly associated with a high LDL/HDL-C ratio (OR 3.4) and hypertriglyceridemia (OR 2.2) in fathers. Approximately 25% of parents and children reported at least two physical activities twice a week. The 23% of children who were passive smokers presented a far more adverse risk profile than children without exposure to second-hand smoke.

CONCLUSION

Intergenerational lifestyle habits affect cardiovascular risk factors within biological families. As lifestyle habits are predictable, they may be used for implementation of family-based CVD prevention strategies.

Parental and childhood overweight in sedentary and active adolescents

We studied whether the prevalence of overweight since age 2 years differed in sedentary and active adolescents (N=346). Further, we analyzed the energy intake of sedentary and active adolescents across 12 years. BMI was assessed annually since birth, energy intake since age 13 months and parents' BMI from the time their child was 7 months old in a longitudinal atherosclerosis prevention study. Data on physical activity were collected at age 13 years (N=560). Sedentary and Active groups were formed by upper and lower physical activity tertile cut-points. Girls Sedentary at 13 years were more often overweight than Active peers already since age 2 years (P=0.048). Activity habits were not associated with energy intake. Conversely, among boys, activity habits in adolescence were not associated with childhood overweight, while the energy intake of Active boys was higher than that of Sedentary boys (P=0.008). Parental overweight was not associated with the physical activity of children; however, Sedentary girls more often had an overweight mother than Active girls (P=0.021). In conclusion, overweight during early years of life is more common among girls who are Sedentary as adolescents than in Active peers. Overweight mothers more often have Sedentary daughters than normal-weight mothers. A healthy lifestyle right from early childhood requires active support.

Who eats healthily? A population-based study among young Swiss residents

OBJECTIVE

To assess whether Swiss residents aged 15-24 years follow current nutritional guidelines and whether differences exist according to gender and weight status.

DESIGN

Cross-sectional national survey.

SETTING

Switzerland.

SUBJECTS

The 1786 participants (48·4 % women) were divided into overweight, normal weight and underweight. We used traditional BMI cut-offs for people ≥18 years of age (underweight = BMI < 18·5 kg/m2, normal weight = BMI ≥ 18·5 kg/m2 and <25 kg/m2, overweight = BMI ≥ 25 kg/m2) and age- and gender-appropriate tables for people aged <18 years, with BMI calculated from self-reported weight and height. We performed bivariate analyses by gender, and then bivariate and multivariate analyses comparing overweight to normal weight people (excluding underweight, n 129, 71·6 % women) regarding adherence to recommendations for fruit, vegetables, meat, fish and dairy products; physical activity; attitude towards body weight; depression, smoking and alcohol consumption.

RESULTS

Overall, adherence to nutritional guidelines was low, particularly for vegetables and dairy products. Women had a higher adherence than men except for fish and dairy products. In the multivariate analyses, overweight women had a lower vegetable intake, were less satisfied with body weight and had more often been on a diet, whereas overweight men were less satisfied with body weight and wanted to lose weight more often than their normal weight peers. There were no significant differences for physical activity.

CONCLUSIONS

Overweight prevention programmes should target youth specifically by gender and promote an appropriate self-perception. Overweight women should be encouraged to eat more vegetables and men to be more sensitised on healthy food. Further research is needed to assess how to make nutritional guidelines more adaptable to young people's daily life.

Physical activity and body composition changes during military service

PURPOSE

To examine how body composition changes in different body mass index (BMI) categories among young Finnish men during military service, which is associated with marked changes in diet and physical activity. In addition, this study examined how reported previous physical activity affected the body composition changes.

METHODS

Altogether 1003 men (19 yr) were followed throughout their military service (6-12 months). Height, weight, BMI, waist circumference, and waist-to-hip ratio (WHR) were recorded. Previous physical activity was assessed at the beginning of the service by a questionnaire. Body composition was measured by bioelectrical impedance assessments (BIA) at the beginning and at the end of the service. The measured parameters were fat mass (FM), fat percentage (fat %), fat-free mass (FFM), visceral fat area (VFA), lean body mass (LBM), and skeletal muscle mass (SMM).

RESULTS

On average, military training decreased weight by 0.7%, FM by 9.7%, fat % by 6.6%, and VFA by 43.4%. FFM increased by 1.3%, LBM by 1.2%, and SMM by 1.7%. The group of underweight and normal-weight men gained weight, FM, and FFM, whereas overweight and obese men lost weight and FM and gained FFM. FM was most reduced in the groups of overweight (20.8%) and obese (24.9%) men. The amount of VFA was reduced in all BMI groups (38%-44%). Among overweight men who reported being inactive previous to the military service, more beneficial changes in body composition were observed compared with those who reported being physically active.

CONCLUSIONS

The lifestyle changes associated with military service markedly reduce fat tissue and increase the amount of lean tissue. These beneficial changes are prominent among previously inactive subjects with high BMI.

Prevalence of overweight and obesity among 7-9-year-old children in Aveiro, Portugal: comparison between IOTF and CDC references

OBJECTIVE

To estimate the prevalence of overweight and obesity in schoolchildren from Aveiro, Portugal, according to two criteria: the International Obesity Task Force (IOTF) and the US Centers for Disease Control and Prevention (CDC) cut-offs.

DESIGN

Weight, height and waist circumference were measured. Using the BMI, gender- and age-specific prevalences of overweight and obesity were determined according to the IOTF cut-offs extrapolated from an adult BMI of 25 and 30 kg/m2 and the CDC cut-off values of 85th and 95th BMI percentile.

SETTING

Aveiro, Portugal.

SUBJECTS

A random representative sample of 905 children (457 boys; 448 girls) aged 7-9 years.

RESULTS

The prevalence of excess weight (overweight and obesity) was lowest according to IOTF cut-offs compared to CDC (28.1 % v. 31.2 %), especially obesity (8.1 % v. 14.0 %). However, the CDC and IOTF criteria have a strong agreement (Cohen's k = 0.755; P < 0.001). There were significant differences in excess weight between boys and girls according to the CDC (26.9 % v. 35.7 %; P = 0.003). Obese children are younger and the majority present abdominal obesity.

CONCLUSIONS

The present study shows a high prevalence of excess weight in Aveiro children, similar to other Portuguese regions and among the highest in Europe, especially in the female gender. The IOTF cut-off values give a lower prevalence of excess weight, namely obesity.

Physical activity as a predictor of adolescent body fatness: a systematic review

Adolescent obesity has increased dramatically in several countries in recent decades; however, the contribution of physical activity level to adolescent adiposity requires clarification. This article investigates the effect of physical activity on subsequent levels of adiposity in adolescence. The methodological aspects of the studies included in this article, particularly in terms of measurement accuracy for both exposure (physical activity) and outcome (adiposity) variables, are also evaluated. Systematic searches of the literature were undertaken using online databases, including PubMed/MEDLINE, examination of citations and contacting of authors. The online databases were searched from their earliest records until 2007. Only longitudinal studies with 50 or more adolescents were included. Two independent reviewers assessed the quality of the studies using the Downs and Black checklist. Thirteen observational, five experimental and six quasi-experimental studies (without a control group) were identified. Almost all studies were carried out in high-income settings and showed protective effects of physical activity for both prevention and treatment of adolescent obesity. However, experimental studies undertaken with obese adolescents at baseline usually combined physical activity with dietary changes, making it difficult to assess the effect of physical activity itself on the treatment of obesity. Physical activity estimated from questionnaires and body mass index (BMI) were the most frequently used measures. Despite the feasibility of using these approaches in epidemiological studies, significant limitations are evident. Questionnaires are subjective and adolescents may not report physical activity level accurately. Furthermore, BMI is not an accurate measure of fatness for adolescents, as it is also associated with lean mass, hence bias may arise from its longitudinal association with physical activity level. Despite the majority of studies reviewed showing protective effects of physical activity on adiposity, particularly in individuals who are obese at baseline, the current literature on this issue is sparse and several methodological drawbacks are evident. The main limitations relate to a lack of validity in the measurements of both physical activity and body composition. Further studies are needed in order to generate evidence-based recommendations for the quantity and quality of adolescent physical activity required to prevent or treat adolescent obesity.

Ethnic and gender differences in physical activity levels among 9-10-year-old children of white European, South Asian and African-Caribbean origin: the Child Heart Health Study in England (CHASE Study)

BACKGROUND

Ethnic differences in physical activity in children in the UK have not been accurately assessed. We made objective measurements of physical activity in 9-10-year-old British children of South Asian, black African-Caribbean and white European origin.

METHODS

Cross-sectional study of urban primary school children (2006-07). Actigraph-GT1M activity monitors were worn by 2071 children during waking hours on at least 1 full day. Ethnic differences in mean daily activity [counts, counts per minute of registered time (CPM) and steps] were adjusted for age, gender, day of week and month. Multilevel modelling allowed for repeated days within individual and clustering within school.

RESULTS

In white Europeans, mean daily counts, CPM and mean daily steps were 394,785, 498 and 10,220, respectively. South Asian and black Caribbean children recorded more registered time per day than white Europeans (34 and 36 min, respectively). Compared with white Europeans, South Asians recorded 18 789 fewer counts [95% confidence interval (CI) 6390-31 187], 41 fewer CPM 95% CI 26-57) and 905 fewer steps (95% CI 624-1187). Black African-Caribbeans recorded 25 359 more counts (95% CI 14 273-36 445), and similar CPM, but fewer steps than white Europeans. Girls recorded less activity than boys in all ethnic groups, with 74 782 fewer counts (95% CI 66 665-82 899), 84 fewer CPM (95% CI 74-95) and 1484 fewer steps (95% CI 1301-1668).

CONCLUSION

British South Asian children have lower objectively measured physical activity levels than European whites and black African-Caribbeans.

Overweight/obesity and factors associated with body mass index during adolescence: the VYRONAS study

AIM

To describe overweight and obese adolescents and to determine any correlations between an adolescent's body mass index (BMI) with personal (age, gender), lifestyle (sedentary/sport activities, smoking status) and parental (smoking status, BMI, number of cars) characteristics.

METHODS

Cross-sectional data on weight, height and various characteristics from 2008 Greek adolescents (12- to 17-year olds, 50.85% boys), measured in 2005-2007, were used.

RESULTS

Almost 1 in 5 (19.2%) boys and 1 in 7 (13.2%) girls 12-17 years of age were overweight while 4.4% of the boys and 1.7% of the girls were obese. The adolescents' age, mother's smoking status, father's and mother's BMI predicted boys' and girls' BMI (b = 0.551, 0.203, 0.110, 0.495 for boys, b = 0.233, 0.187, 0.180, 0.531 for girls, respectively, p < or = 0.05). Univariate analysis revealed that television watching/using personal computer/playing video games and playtime were not correlated with BMI, while an inverse association of exercising for > or = 5 h/week and BMI was found in both boys and girls (b =-1.098, -0.528, p = 0.005, 0.004 respectively).

CONCLUSION

The results of our study underline the high prevalence of obesity during adolescence in Greece. Age and parental unhealthy behaviour (increased BMI and maternal smoking status) were positive predictors of increased BMI of adolescents in both genders.

Relevance of animal models to human eating disorders and obesity

BACKGROUND AND RATIONALE

This review addresses the role animal models play in contributing to our knowledge about the eating disorders anorexia nervosa (AN) and bulimia nervosa (BN) and obesity.

OBJECTIVES

Explore the usefulness of animal models in complex biobehavioral familial conditions, such as AN, BN, and obesity, that involve interactions among genetic, physiologic, psychological, and cultural factors.

RESULTS AND CONCLUSIONS

The most promising animal model to mimic AN is the activity-based anorexia rodent model leading to pathological weight loss. The paradigm incorporates reward elements of the drive for activity in the presence of an appetite and allows the use of genetically modified animals. For BN, the sham-feeding preparation in rodents equipped with a gastric fistula appears to be best suited to reproduce the postprandial emesis and the defects in satiety. Animal models that incorporate genes linked to behavior and mood may clarify biobehavioral processes underlying AN and BN. By contrast, a relative abundance of animal models has contributed to our understanding of human obesity. Both environmental and genetic determinants of obesity have been modeled in rodents. Here, we consider single gene mutant obesity models, along with models of obesigenic environmental conditions. The contributions of animal models to obesity research are illustrated by their utility for identifying genes linked to human obesity, for elucidating the pathways that regulate body weight and for the identification of potential therapeutic targets. The utility of these models may be further improved by exploring the impact of experimental manipulations on the behavioral determinants of energy balance.

Divergent physical activity and novel alternative responses to high fat feeding in polygenic fat and lean mice

We determined whether altered physical activity levels might underlie the contrasting adiposity of a divergently selected polygenic murine model of metabolic syndrome (Fat; F) and leanness (Lean; L) mice. We measured physical activity with a long term running wheel experiment and performed an additional high fat diet intervention. Further, we measured posture allocation by visual monitoring within the home cage as a non-exercise correlate of 'normal' physical activity. Whilst initially similar, running wheel activity of the F line declined with age, while the activity of the L line increased. Food intake was higher in the L line and increased with wheel exposure. Vertical rearing measured by video quantification in the home cage, without the stimulus of a running wheel was also significantly higher in the L line. The two lines developed novel alternate strategies to defend their body weight when exposed to high fat diets with a running wheel. F mice increased their running wheel activity, and despite unaltered food intake, still gained weight. L mice reduced their food intake and maintained activity levels without a significant change in body weight. Phenotypic selection for divergence in body fat content has co-segregated with a genetic predisposition for divergent physical activity levels and different strategies for coping with exposure to high fat diets that will facilitate the discovery of the genes underlying these important obesity related traits.

Socioeconomic status and adiposity in childhood: a systematic review of cross-sectional studies 1990-2005

BACKGROUND

Sobal and Stunkard's review (1989) of 34 studies from developed countries published after 1941, found inconsistent relationships between socioeconomic status (SES) and childhood adiposity. Inverse associations (36%), no associations (38%), and positive associations (26%) were found in similar proportions. In view of the trends in pediatric obesity, the relationship between SES and adiposity may have changed.

OBJECTIVE

To describe the cross-sectional association between SES and adiposity in school-age children from western developed countries in epidemiological studies since 1989.

METHODS AND PROCEDURES

PubMed database was searched to identify potentially relevant publications. Epidemiological studies from western developed countries presenting cross-sectional data on the bivariate association between an SES indicator and objectively measured adiposity in childhood (5-18 years), carried out after 1989 were included. SES indicators included parental education, parental occupation, family income, composite SES, and neighborhood SES.

RESULTS

Forty-five studies satisfied the review criteria. SES was inversely associated with adiposity in 19 studies (42%), there was no association in 12 studies (27%), and in 14 studies (31%) there was a mixture of no associations and inverse associations across subgroups. No positive SES-adiposity associations were seen in unadjusted analyses. With parental education as the SES indicator, inverse associations with adiposity were found in 15 of 20 studies (75%).

DISCUSSION

Research carried out within the past 15 years finds that associations between SES and adiposity in children are predominately inverse, and positive associations have all but disappeared. Research is needed to understand the mechanisms through which parental social class influences childhood adiposity.

Prevalence of obesity in 6- and 9-year-old children living in Central-North Italy. Analysis of determinants and indicators of risk of overweight

The objective of our article is to survey the prevalence of overweight and obesity among 6- and 9-year-old children in Emilia-Romagna, a region of Central-North Italy, and to study the eating habits and behaviours of these children and their families. During 2003 and 2005, we analysed a stratified sample of the general population of children attending pre-school (2681 children aged 6 years) and primary school (2955 children aged 9 years). Their height and weight were measured by healthcare workers. In the 6-year-old children, information concerning their eating habits was collected by means of a questionnaire completed by their parents. The prevalence of overweight was 16.5% in 6-year-old children and 20.6% in 9-year-old children. The increase of overweight from 6- to 9-year-old children was observed in males (13.5% in 6-year-old/21.3% in 9-year-old boys), but not in females. The prevalence of obesity was 8.9% in children aged 6 years and 9.0% in those aged 9 years, and it was higher in comparison with Italian surveys carried out in 1993 and in 2001: 7.5% in 6-year-old and 7.8% in 9-year-old children in 1993, and 6.6% in 6-year-old and 7.2% in 9-year-old children in 2001. In pre-school children, overweight and obesity were closely influenced by the education level, occupation and nutritional status of the parents.

Cardiorespiratory fitness relates more strongly than physical activity to cardiovascular disease risk factors in healthy children and adolescents: the European Youth Heart Study

BACKGROUND

Physical activity and cardiorespiratory fitness are closely related to health variables in adults, especially those considered to be among risk factors for cardiovascular diseases. The possible tracking of cardiovascular disease risk factors from childhood to adulthood makes it important to increase our understanding of the complex relationships between physical activity, cardiorespiratory fitness and cardiovascular risk factors early in life.

DESIGN

A cross-sectional, school-based study on healthy children and adolescents, aged 9-10 years (295 girls, 295 boys) and 15-16 years (302 girls, 233 boys) was performed during a school year in Sweden and Estonia, as part of the European Youth Heart Study.

METHODS

Total physical activity, and minutes spent in inactivity and activity of moderate or higher intensity were measured by accelerometry. A maximal ergometer bike test was used for estimation of cardiorespiratory fitness. The risk factors included blood pressure and fasting blood levels of insulin, glucose, triglycerides, total cholesterol and high-density lipoprotein cholesterol.

RESULTS

Canonical correlations between physical activity and cardiorespiratory fitness versus cardiovascular disease risk factors showed significant associations in both age and sex groups (rc=0.46-0.61, P<0.0001). The cardiorespiratory fitness was found to be the strongest contributor to these relationships. In girls high values of the physical activity variables were also associated with a favourable cardiovascular profile.

CONCLUSIONS

Cardiorespiratory fitness relates more strongly to cardiovascular risk factors than components of objectively measured physical activity in children and adolescents. Physical activity becomes more important in the 15-year-old adolescents, indicating that these modifiable lifestyle factors increase in importance with age.

Physical activity, overweight and central adiposity in Swedish children and adolescents: the European Youth Heart Study

Background

The aim of this work was to study the associations of physical activity (PA) and other factors predisposing to overweight, with overweight and central adiposity in children and adolescents.

Methods

A total of 557 Swedish children (9.5 ± 0.3 y) and 517 adolescents (15.6 ± 0.4 y) from the European Youth Heart Study participated in this study. Logistic regression analyses were used to examine the associations of PA, as measured by accelerometry, and other determinants (i.e. television viewing, birth weight, maternal educational level and parental overweight) with total and central adiposity. Body mass index and waist circumference cut-off values proposed by the IOTF and the Bogalusa Heart Study (i.e. waist measures for predicting risk factors clustering, hereinafter called high-risk waist circumference), respectively, were used. Fatness was estimated from skinfold thicknesses and dichotomized using the 85^th sex- and age-specific percentile (high/low).

Results

Children and adolescents who had a low level (first tertile) of vigorous PA, were more likely to be overweight (including obesity) and to have a high-risk waist circumference, than those with a high level (third tertile) of vigorous PA. Similarly, those subjects who had a low or middle level (second tertile) of total PA were more likely to be overweight than those who had a high level of total PA. Among the PA variables, only vigorous PA was associated with high total fatness. Birth weight and television viewing, were also associated with higher odds of having a high-risk waist circumference, but these associations were attenuated once either total or vigorous PA variable was included in the model. Those subjects who had two overweight parents were more likely to be overweight and to have a high-risk waist circumference independently of PA variables, compared to those whose parents were not overweight.

Conclusion

Low levels of total PA and especially vigorous PA may play an important role in the development of overweight and excess of central adiposity in children and adolescents, independently of a number of factors such as television viewing and birth weight. In addition, the data suggest that the association between television viewing and central fat deposition could be attenuated if enough vigorous PA is accumulated. Longitudinal and intervention studies are needed to confirm these findings.

Habitual physical activity and body composition of black township adolescents residing in the North West Province, South Africa

Objective

It is known that stunting and obesity affect a large proportion of children in the world, and these can be affected by the physical activity levels of the children. In the present study, we evaluated the association between physical activity, physical development and body composition in black adolescent children.

Design

Cross-sectional study.

Setting

Black township schools in the North West Province, South Africa.

Methods

Three-hundred and thirteen grade 8 children were included in the Physical Activity in Youth study. Anthropometric measurements, body composition measures and maturity level as assessed by Tanner stages were determined in these children. In addition, Previous Day Physical Activity Recall questionnaires were administered on the children to record the various activities they undertake daily.

Results

The demographic characteristics of the children showed a high level of homogeneity. A high prevalence of stunting (16.3%) was observed in the children, which was higher in boys than in girls (21.6 vs. 12.3%). Also prevalent was overweight/obesity (8.6%), but this was higher in girls than in boys (13.4 vs. 1.6%). The children also showed a reduction in levels of physical activity with advancement in maturity; furthermore, boys showed a more central form of fat deposition whilst girls showed more gynoid deposition.

Conclusions

The study revealed that physical activity plays a role in determining body composition, and further indicated that physical activity is associated with favourable body composition measures. Children who were more active were likely to have less fat deposits.

Moderate-vigorous physical activity and body fatness in Chinese urban school children

BACKGROUND

The exact relation between moderate-vigorous physical activity (MVPA) and body fatness in children has yet to be fully defined. This study examined the relationship between MVPA and body fatness in Chinese urban school children aged 9-11 years, in an 8 month longitudinal study.

METHODS

Two hundred and ten children (aged 9-11 years; 97 boys and 113 girls) were recruited from two public primary schools in the Beijing urban area. The baseline and the 8 month follow-up percent body fat (fat%), fat mass (FM), body mass index (BMI), waist size, hip size and the waist : hip ratio were investigated as measures of body fatness. Habitual MVPA level (activity-related energy expenditure, AEE) was measured using a validated self-report questionnaire recall.

RESULTS

Nine-year-old girls who were in the top quartile for MVPA had significantly lower fat% than other girls at the same age (P < 0.05); 10-11-years girls who were in the top quartile for MVPA had significantly less increase in all of the indices of body fatness (P < 0.05). There was no difference in fat% between the highly physically active (top quartile for MVPA) and less active 9-11 year boys in both cross-sectional and longitudinal statistical analyses.

CONCLUSIONS

Highly physically active girls had lower fat% and less increase in body fatness. In light of world trends showing increasing childhood obesity, this study supports the hypothesis that MVPA might be effective in fighting excess body fat gain in Chinese school-age girls.

The epidemic of obesity in children and adolescents in the world

The prevalence of obesity has reached alarming levels, affecting virtually both developed and developing countries of all socio-economic groups, irrespective of age, sex or ethnicity. Concerning childhood obesity, it has been estimated that worldwide over 22 million children under the age of 5 are severely overweight, and one in 10 children are overweight. This global average reflects a wide range of prevalence levels, with the prevalence of overweight in Africa and Asia averaging well below 10% and in the Americas and Europe above 20%. The proportion of school-age children affected will almost double by 2010 compared with the most recently available surveys from the late 1990s up to 2003. In the European Union, the number of children who are overweight is expected to rise by 1.3 million children per year, with more than 300,000 of them becoming obese each year without urgent action to counteract the trend. By 2010 it is estimated that 26 million children in E.U. countries will be overweight, including 6.4 million who will be obese. Moreover, in the U.S.A. the prevalence of obesity in adolescents has increased dramatically from 5% to 13% in boys and from 5% to 9% in girls between 1966-70 and 1988-91. In this review paper we present the epidemiology of obesity in children and adolescents, including prevalence rates, trends, and risk factors associated with this phenomenon.

TV viewing and physical activity are independently associated with metabolic risk in children: the European Youth Heart Study

BACKGROUND

TV viewing has been linked to metabolic-risk factors in youth. However, it is unclear whether this association is independent of physical activity (PA) and obesity.

METHODS AND FINDINGS

We did a population-based, cross-sectional study in 9- to 10-y-old and 15- to 16-y-old boys and girls from three regions in Europe (n = 1,921). We examined the independent associations between TV viewing, PA measured by accelerometry, and metabolic-risk factors (body fatness, blood pressure, fasting triglycerides, inverted high-density lipoprotein (HDL) cholesterol, glucose, and insulin levels). Clustered metabolic risk was expressed as a continuously distributed score calculated as the average of the standardized values of the six subcomponents. There was a positive association between TV viewing and adiposity (p = 0.021). However, after adjustment for PA, gender, age group, study location, sexual maturity, smoking status, birth weight, and parental socio-economic status, the association of TV viewing with clustered metabolic risk was no longer significant (p = 0.053). PA was independently and inversely associated with systolic and diastolic blood pressure, fasting glucose, insulin (all p < 0.01), and triglycerides (p = 0.02). PA was also significantly and inversely associated with the clustered risk score (p < 0.0001), independently of obesity and other confounding factors.

CONCLUSIONS

TV viewing and PA may be separate entities and differently associated with adiposity and metabolic risk. The association between TV viewing and clustered metabolic risk is mediated by adiposity, whereas PA is associated with individual and clustered metabolic-risk indicators independently of obesity. Thus, preventive action against metabolic risk in children may need to target TV viewing and PA separately.

The criterion validity of a last 7-day physical activity questionnaire (SAPAQ) for use in adolescents with a wide variation in body fat: the Stockholm Weight Development Study

OBJECTIVE

The aim of the present study was to assess the criterion validity of a newly developed self-reported last 7-day physical activity questionnaire (SAPAQ) for use in Swedish adolescents with a wide variation in body fatness.

MEASUREMENTS

We compared the self-reported total number of MET-minutes with objectively assessed variables of physical activity obtained by accelerometry in 49 (18 male, 31 female subjects) 17-year-old adolescents.

RESULTS

Self-reported physical activity was significantly and inversely related to time spent sedentary (r=-0.45; P<0.001) and significantly and positively associated with time spent in physical activity (r=0.51; P<0.001) and the total amount of physical activity (r=0.49; P<0.001). Gender and body fat did not affect the associations between self-reported and objectively assessed physical activity.

CONCLUSION

Our results indicate that the newly developed questionnaire is a valid method for ranking individuals in terms of the total amount of physical activity in Swedish adolescents.

Physical activity and sedentary behavior: a review of longitudinal studies of weight and adiposity in youth

AIM

To review the published prospective observational studies of the relationship of physical activity and sedentary behavior with the development of overweight and adiposity, with an emphasis on methodologic issues.

METHODS

Sample size, population studied, length of follow-up, assessment of exposure (physical activity, inactivity, or sedentary behavior), assessment of outcome (relative weight, overweight, % body fatness, adiposity), statistical approach, and main findings were extracted, summarized, and key methodological issues highlighted.

RESULTS

In total, 17 studies of physical activity and 15 studies of inactivity/sedentary behavior were identified; as these were not mutually exclusive, 20 unique studies were reviewed. Results were mixed, with most studies showing an inverse association of physical activity with weight or fatness outcomes and/or a direct association of inactivity/sedentary behavior with weight or fatness outcomes. The effects identified were generally of small magnitude. Imprecise measurement of activity exposures likely weakens the observed relationships. Most studies used a pre-post design and had limited duration of follow-up (< or = 2y). Studies with longer and more frequent follow-up did not always use the most advantageous statistical approach.

CONCLUSIONS

On balance, the available evidence from prospective observational studies suggests that increased physical activity and decreased sedentary behavior are protective against relative weight and fatness gains over childhood and adolescence. In addition to improved measurement methods, longer and more frequent follow-up as well as truly longitudinal analysis methods would help establish these important prevention and intervention targets, and identify subgroups or development periods where interventions would likely be effective.