Magnesium Intake, C-Reactive Protein, and Muscle Mass in Adolescents.

Background: Adult studies have suggested that magnesium intake may regulate C-reactive protein (CRP) and muscle mass, known risk factors for cardiometabolic diseases. Given the large deficiencies in magnesium intake in adolescents, we aimed to investigate sex and race differences in dietary magnesium intake and test the hypothesis that lower magnesium intake is associated with higher CRP and lower muscle mass. Methods: A total of 766 black and white adolescents, 14 to 18 years old (51% black; 50% female) were previously recruited. Diet was assessed with four to seven independent 24-h recalls. Body composition was measured by dual-energy X-ray absorptiometry. High-sensitivity CRP (hs-CRP), leptin, resistin, and adiponectin were measured using fasting blood samples by ELISA. Results: There were sex and race differences in the daily consumption of magnesium. The average daily magnesium intakes were 200.66 ± 7.09 mg and 205.03 ± 7.05 mg for males and females, respectively, far below the recommended amounts of 410 mg for males and 360 mg for females. White subjects (217.95 ± 6.81 mg/day) consumed more than black subjects (187.75 ± 6.92 mg/day). Almost none of the adolescents met the recommendations. Adjusted multiple linear regressions revealed that lower magnesium intake was associated with higher hs-CRP and lower fat-free mass (FFM) (p-values < 0.05). Higher hs-CRP was associated with lower FFM. Moreover, an interaction between magnesium intake and hs-CRP on FFM was identified (p-value < 0.05). Lower magnesium intake amplified the inverse relationships between hs-CRP and FFM (p-values < 0.05). Conclusion: Magnesium consumption in our adolescents was far below daily recommended levels with male and black subjects consuming less than female and white subjects. Lower magnesium intake was associated with higher CRP and lower muscle mass. Low magnesium intake may also augment the inverse relationship between CRP and FFM.

Higher chocolate intake is associated with longer telomere length among adolescents.

BACKGROUND: Chocolate intake has shown cardiometabolic health benefits. Whether chocolate has any effect on cellular aging remains unknown. We aimed to test the hypothesis that higher chocolate intake is associated with longer leukocyte telomere length (LTL) in adolescents. METHODS: A total of 660 adolescents (aged 14-18 years) were included in the analysis. The chocolate intake was assessed by 7-day, 24-h dietary recalls and split into three groups, which were none, <2 servings/week, and 2 servings/week or more. LTL (T/S ratio) was determined by a modified quantitative polymerase chain reaction-based assay. RESULTS: Among the 660 adolescents, 58% did not take any chocolate, 25% consumed <2 servings/week, and 17% consumed ≥2 servings/week. Compared to non-consumers, adolescents who consumed chocolate of ≥2 servings/week had 0.27 standard deviation (SD) longer LTL (p = 0.014). Higher chocolate consumption was associated with increased apolipoprotein A1 (ApoA1) (p = 0.038) and ApoA1/high-density lipoprotein (HDL) (p = 0.046). Moreover, higher ApoA1/HDL levels were correlated with longer LTL (p = 0.026). CONCLUSION: Adolescents who consume 2 servings/week or more of chocolate candy have longer LTL compared with non-consumers, and ApoA1/HDL pathway may be involved in this relationship.

Race, Gender, Family Structure, Socioeconomic Status, Dietary Patterns, and Cardiovascular Health in Adolescents.

BACKGROUND: Dietary patterns represent a broad picture of food and nutrient consumption and may be more predictive of health outcomes than individual foods and nutrients. OBJECTIVE: We investigated the relations among race, gender, family structure, parental socioeconomic status (SES), dietary patterns, and cardiovascular disease (CVD) profiles among adolescents in the southeastern region of the United States. METHODS: A total of 743 adolescents from a cross-sectional study were divided into 4 dietary pattern groups by K-means cluster analysis. Multinomial logistic regression was performed to determine the relations among the parental SES, family structures, and dietary patterns of the adolescents. Associations between dietary patterns and CVD profiles were analyzed by multiple linear regression. RESULTS: Four dietary patterns were derived: "healthy" (17%), "snacks and sweets" (26%), "processed meat" (20%), and "sugar-sweetened beverage (SSB) and fried food" (37%). Whites and females were more likely to have a "healthy" dietary pattern (Ps < 0.001). There were significant race/ethnicity differences in family structures, SES, and dietary patterns (Ps < 0.05). In whites, higher mother's education and father's education and occupation were associated with greater likelihood of a "healthy" dietary pattern (Ps < 0.05). Stay-at-home mother was associated with less likelihood of an "SSB and fried food" pattern (P = 0.023). In blacks, higher mother's occupation, father's education, and living with both parents were associated with more likelihood of a "healthy" dietary pattern (Ps < 0.05). Stay-at-home father was associated with less likelihood of the "snacks and sweets" (P = 0.025) and "SSB and fried food" dietary patterns (P = 0.044). Overall, adolescents with poor dietary patterns exhibited higher percentage body fat, waist circumference, systolic blood pressure, fasting insulin, homeostasis model assessment of insulin resistance, C-reactive protein, and total triglyceride (Ps < 0.05). CONCLUSIONS: Our data suggest that family structure, parental working status, and SES are associated with the diet quality in adolescents. Moreover, "snacks and sweets," "processed meat," and "SSB and fried food" dietary patterns are all associated with worse CVD risk profiles.

Proportionality at birth and left ventricular hypertrophy in healthy adolescents.

BACKGROUND: Perinatal growth has important implications for cardiac development. Low birth weight is associated with cardiovascular (CV) events and mortality, and animal studies have shown that fetal growth restriction is associated with cardiac remodeling in the perinatal period leading to a permanent loss of cardiomyocyte endowment and compensatory hypertrophy. AIMS: To determine associations of birthweight (BW) and multiple proportionality indexes (body mass index (BMI); weight/length2 and Ponderal index (PI); weight/length3) at birth on one hand, with left ventricular (LV) structure and function during adolescence. SUBJECTS: 379 healthy adolescents aged 14-18 years in Augusta, Georgia. OUTCOME MEASURES: LV structure and function parameters, including intraventricular septal thickness in diastole (IVSd), LV internal dimension in diastole (LVIDd), LV internal diameter in systole (LVIDs), LV posterior wall thickness in diastole (LVPWd), relative wall thickness (RWT), midwall fractional shortening (MFS), and ejection fraction, were assessed by echocardiography. RESULTS: When associations of birthweight, birth BMI, and birth PI with LV structure and function parameters were separately evaluated with linear regression adjusting for age, sex, race, Tanner stage, socioeconomic status, and physical activity, significant positive associations of BW with LVIDd (P = 0.004), birth BMI with LV mass index (P = 0.01), and birth PI with IVSd (P = 0.02), LVPWd (P = 0.03), and LV mass index (P = 0.002) were identified. When LV structure and function parameters were compared across PI tertiles, a significant U-shaped trend for LV mass index (Pquadratic = 0.04) was identified. CONCLUSIONS: Our adolescent data suggest that proportionality at birth may identify associations between perinatal growth and cardiac remodeling independent of birthweight alone.

Effects of a 3-month vigorous physical activity intervention on eating behaviors and body composition in overweight and obese boys and girls.

PURPOSE: This study aims to analyze the effects of a 3-month vigorous physical activity (VPA) intervention on eating behavior and body composition in overweight and obese children and adolescents. METHODS: Forty-seven participants (7-16 years) took part in the study: 28 were assigned to the intervention group (IG) (10 boys and 18 girls) and 19 in a control group (CG) (8 boys and 11 girls). Body composition (dual-energy X-ray absorptiometry), anthropometrics (body mass, height, and body mass index (BMI)), and eating behavior traits (Three-Factor Eating Questionnaire-R21C) were determined before and after the VPA intervention. RESULTS: A decrease in the percentage of body fat and BMI (-2.8% and -1.8%, respectively), and an increase in most lean mass variables were found in the IG (all p ≤ 0.05). In relation to the eating behavior traits, IG subjects showed a 14% reduction in the Emotional Eating score (p = 0.04), while Cognitive Restraint score did not change after the VPA intervention. The baseline factors of the questionnaire predicted changes in body mass and fat mass variables only in the CG. CONCLUSION: A 3-month VPA intervention influenced eating behaviors of overweight or obese young, especially the Emotional Eating factor, in the presence of favorable body composition changes.

Total, insoluble, and soluble dietary fiber intake and insulin resistance and blood pressure in adolescents.

BACKGROUND/OBJECTIVES: To evaluate sex and race differences in fiber intakes, which are understudied in adolescents, and to investigate whether low insoluble and soluble fiber intakes would be associated with higher risk for insulin resistance and blood pressure (BP). SUBJECTS/METHODS: A total of 754 black and white adolescents, 14 to 18 years old (49.2% blacks; 50.3% female), were previously recruited in Augusta, Georgia, USA, between 2001 and 2005. Diet was assessed with four to seven independent 24 h dietary recalls. RESULTS: The average daily consumption of total, insoluble, and soluble fiber were 10.9, 6.7, and 4.0 g, respectively. Only two adolescents met their daily fiber intake recommendation. Adjusted multiple linear regressions revealed that increasing dietary fiber intake from current averages to recommendation levels (12 g to 38 g in the male and 9.9 g to 25 g in the female) were associated with predicted decreases of 5.4 and 3.0 mg/dL fasting glucose, 7.0 and 5.0 mg/dL fasting insulin, 1.6 and 1.1 HOMA-IR, 6.3 and 3.7 mm Hg SBP, and 5.2 and 3.0 mm Hg DBP in the males and females, respectively (all p < 0.05). Furthermore, both insoluble and soluble fiber intakes were inversely associated with fasting insulin and HOMA-IR (p < 0.05), whereas only soluble fiber intake was found to be associated with BP (p < 0.05). CONCLUSIONS: Fiber consumption in adolescents is far below daily-recommended levels across all sex and race groups. Lower fiber intake of all types is associated with higher insulin level. Fiber Intake at recommendation levels may be associated with significant cardiometabolic benefits.

Epigenome-Wide Association Study of Dietary Fiber Intake in African American Adolescents.

SCOPE: Low fiber intake is associated with increased risk for cardiovascular disease (CVD) and cancer. However, the underlying mechanisms are not well understood. Two hypotheses are tested: 1) dietary fiber would be associated with DNA methylation levels; 2) those DNA methylation changes would be associated with visceral adiposity and inflammation. Also the possibility that the associations between fiber and DNA methylation levels might be confounded with folic acid intake as sensitivity analysis are explored. METHODS AND RESULTS: An epigenome-wide association study is conducted using Illumina 450K Bead-Chip on leukocyte DNA in 284 African American adolescents. Linear regression is performed to identify differentially methylated CpG sites associated with fiber. The methylation levels of 3 CpG sites (cg15200711, cg19462022, and cg07035602) in LPCAT1 and RASA3 genes are associated with fiber (false discovery rate [FDR] < 0.05) after adjustment for covariates including folic acid. The methylation levels of cg07035602 and cg19462022 are also associated with visceral adiposity and inflammation. CONCLUSIONS: The data show that DNA methylation levels at LPCAT1 and RASA3 genes are associated with dietary fiber intake as well as with adiposity and inflammation. Future studies are warranted to determine whether epigenetic regulation may underlie the beneficial effects of fiber intake on adiposity and inflammation.

Phylloquinone Intake Is Associated with Cardiac Structure and Function in Adolescents.

BACKGROUND: Associations between childhood vitamin K consumption and cardiac structure and function have not been investigated. OBJECTIVE: We determined associations between phylloquinone (vitamin K-1) intake and left ventricular (LV) structure and function in adolescents. METHODS: We assessed diet with three to seven 24-h recalls and physical activity (PA) by accelerometry in 766 adolescents (aged 14-18 y, 50% female, 49% black). Fat-free soft tissue (FFST) mass and fat mass were measured by dual-energy X-ray absorptiometry. LV structure [LV mass (g)/height (m)2.7 (LV mass index) and relative wall thickness] and function [midwall fractional shortening (MFS) and ejection fraction] were assessed by echocardiography. Associations were evaluated by comparing the LV structure and function variables across tertiles of phylloquinone intake. Prevalence and OR of LV hypertrophy (LV mass index >95th percentile for age and sex) were also assessed by phylloquinone tertiles. RESULTS: The prevalence of LV hypertrophy progressively decreased across tertiles of phylloquinone intake (P-trend < 0.01). Multinomial logistic regression-adjusting for age, sex, race, Tanner stage, systolic blood pressure, FFST mass, fat mass, socioeconomic status, PA, and intakes of energy, fiber, calcium, vitamin C, vitamin D, and sodium-revealed that compared with the highest phylloquinone intake tertile (reference group), the adjusted OR for LV hypertrophy was 3.3 (95% CI: 1.2, 7.4) for those in the lowest phylloquinone intake tertile. When LV structure variables were compared across phylloquinone intake tertiles adjusting for the same covariates, there were significant linear downward trends for LV mass index (6.5% difference, tertile 1 compared with tertile 3) and relative wall thickness (9.2% difference, tertile 1 compared with tertile 3; both P-trend ≤ 0.02). Conversely, significant linear upward trends across phylloquinone intake tertiles were observed for MFS (3.4% difference, tertile 1 compared with tertile 3) and ejection fraction (2.6% difference, tertile 1 compared with tertile 3; both P-trend < 0.04). CONCLUSION: Our adolescent data suggest that subclinical cardiac structure and function variables are most favorable at higher phylloquinone intakes.

Associations between Global DNA Methylation and Telomere Length in Healthy Adolescents.

Emerging evidence suggests that epigenetics regulates telomere dynamics in adults. However, the relationship between these pathways in children and youth remains unknown. Thus, we examined this association in 542 healthy adolescents aged 14 to 18 years old (44.8% African Americans; 55.2% females). Global DNA methylation level (%5-mC) was quantified using ELISA method. Leukocyte telomere length (LTL) was defined as relative telomere to single copy gene (T/S) ratio. Multiple linear regression models, adjusted for age, gender, ethnicity, Tanner stage, BMI, PA, and batch effect, revealed that %5 mC was associated with LTL (adjusted ß = 0.17, p < 0.01). %5 mC accounted for 5.0% of the variation for LTL. A significant gender interaction was identified (p < 0.01). There was an association between %5 mC and LTL in females (all ps < 0.01), but not in males. Further sensitivity analyses by race revealed similar associations in African Americans and whites (all ps < 0.03). The present study, for the first time, shows that lower levels of global DNA methylation are associated with shorter telomere lengths in youth, which may decrease genome stability and augment the susceptibility to diseases. Longitudinal studies are warranted to establish the effects of global DNA methylation on LTL maintenance over time.

The Case for Vigorous Physical Activity in Youth.

Although it is widely recognized that regular physical activity is associated with a variety of health-related benefits in youths, the extent to which vigorous physical activity, as opposed to moderate or light physical activity, may be especially beneficial for youths is not completely understood. This review will examine the evidence for the efficacy of vigorous physical activity for promoting the well-being of youths as indicated by body composition, physical fitness, cardiometabolic biomarkers, and cognitive function. Potential caveats associated with the promotion of vigorous physical activity among youths will also be discussed, as will the inclusion of vigorous physical activity in current recommendations by national organizations for physical activity among youths.

Correction: Race/Ethnicity-Specific Association of Vitamin D and Global DNA Methylation: Cross-Sectional and Interventional Findings.

[This corrects the article DOI: 10.1371/journal.pone.0152849.].

Nonlinear Relationship between Birth Weight and Visceral Fat in Adolescents.

OBJECTIVE: To determine the association of birth weight with abdominal fat distribution and markers known to increase risk for cardiovascular disease and type 2 diabetes in adolescents. STUDY DESIGN: In 575 adolescents aged 14-18 years (52% female, 46% black), birth weight was obtained by parental recall. Fasting blood samples were measured for glucose, insulin, lipids, adiponectin, leptin, and C-reactive protein. Subcutaneous abdominal adipose tissue and visceral adipose tissue were assessed by magnetic resonance imaging. RESULTS: When we compared markers of cardiometabolic risk across tertiles of birth weight, adjusting for age, sex, race, Tanner stage, physical activity, socioeconomic status, and body mass index, there were significant U-shaped trends for homeostasis model assessment of insulin resistance, leptin, and visceral adipose tissue (all Pquadratic < .05). A significant linear downward trend across tertiles of birth weight was observed for triglycerides (Plinear = .03). There were no differences in fasting glucose, blood pressure, total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, adiponectin, C-reactive protein, or subcutaneous abdominal adipose tissue across tertiles of birth weight. CONCLUSIONS: Our data suggest that both low and high birth weights are associated with greater visceral adiposity and biomarkers implicated in insulin resistance and inflammation in adolescents.

Race/Ethnicity-Specific Association of Vitamin D and Global DNA Methylation: Cross-Sectional and Interventional Findings.

OBJECTIVES: Understanding of the influence of vitamin D deficiency on epigenome will provide novel insights into the chronic disease risk. We tested our hypotheses that 1) vitamin D deficiency is associated with global hypomethylation and this association may be race/ethnicity dependent; and 2) vitamin D supplementation will increase global DNA methylation level. METHODS: A two-stage design, cross-sectional observation followed by a 16 week randomized, double- blinded, placebo-controlled trial (RCT) of vitamin D3 supplementation, was undertaken. Global DNA methylation level (percentage of 5-methylcytosine, %5-mC) was quantified using leukocyte DNA with the MethylFlashTM Methylated DNA Quantification kit (Epigentek). Global methylation data was obtained from 454 Caucasians and African Americans (42%) in the observation cohort and 58 African Americans with vitamin D deficiency in the dose responsive RCT. RESULTS: In the cross-sectional study, African Americans had lower %5-mC than Caucasians (P = 0.04). A significant interaction was detected between plasma 25(OH)D and race on %5-mC (P = 0.05), as a positive association was observed between plasma 25(OH)D and %5-mC in African Americans (ß = 0.20, p<0.01), but not in Caucasians (ß = 0.03, p = 0.62). In the 16-week RCT, a dose-response benefit of vitamin D3 supplementation was observed for %5-mC, as indicated by a significant linear upward trend (-0.01 ± 0.01%, placebo; 0.11 ± 0.01%, ~600 IU/day; 0.30 ± 0.01%, ~2,000 IU/day; and 0.65 ± 0.01%, ~4,000 IU/day group; P-trend = 0.04). CONCLUSIONS: Vitamin D deficiency is associated with global hypomethylation in African Americans. Vitamin D3 supplementation increases global DNA methylation in a dose-response manner in African Americans with vitamin D deficiency.

Correlates of dietary energy misreporting among European adolescents: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study.

This study examined the correlates of dietary energy under-reporting (UR) and over-reporting (OV) in European adolescents. Two self-administered computerised 24-h dietary recalls and physical activity data using accelerometry were collected from 1512 adolescents aged 12·5-17·5 years from eight European countries. Objective measurements of height and weight were obtained. BMI was categorised according to Cole/International Obesity Task Force (IOTF) cut-off points. Diet-related attitudes were assessed via self-administered questionnaires. Reported energy intake (EI) was compared with predicted total energy expenditure to identify UR and OV using individual physical activity objective measures. Associations between misreporting and covariates were examined by multilevel logistic regression analyses. Among all, 33·3 % of the adolescents were UR and 15·6 % were OV when considering mean EI. Overweight (OR 3·25; 95 % CI 2·01, 5·27) and obese (OR 4·31; 95 % CI 1·92, 9·65) adolescents had higher odds for UR, whereas underweight individuals were more likely to over-report (OR 1·67; 95 % CI 1·01, 2·76). Being content with their own figures (OR 0·61; 95 % CI 0·41, 0·89) decreased the odds for UR, whereas frequently skipping breakfast (OR 2·14; 95 % CI 1·53, 2·99) was linked with higher odds for UR. Those being worried about gaining weight (OR 0·55; 95 % CI 0·33, 0·92) were less likely to OV. Weight status and psychosocial weight-related factors were found to be the major correlates of misreporting. Misreporting may reflect socially desirable answers and low ability to report own dietary intakes, but also may reflect real under-eating in an attempt to lose weight or real over-eating to reflect higher intakes due to growth spurts. Factors influencing misreporting should be identified in youths to clarify or better understand diet-disease associations.

DNA methylation of the LY86 gene is associated with obesity, insulin resistance, and inflammation.

BACKGROUND: Previous genome-wide association studies (GWAS) have identified a large number of genetic variants for obesity and its related traits, representing a group of potential key genes in the etiology of obesity. Emerging evidence suggests that epigenetics may play an important role in obesity. It has not been explored whether the GWAS-identified loci contribute to obesity through epigenetics (e.g., DNA (deoxyribonucleic acid) methylation) in addition to genetics. METHOD: A multi-stage cross-sectional study was designed. We did a literature search and identified 117 genes discovered by GWAS for obesity and its related traits. Then we analyzed whether the methylation levels of these genes were also associated with obesity in two genome-wide methylation panels. We examined an initial panel of seven adolescent obese cases and seven age-matched lean controls, followed by a second panel of 48 adolescent obese cases and 48 age- and gender-matched lean controls. The validated CpG sites were further replicated in two independent replication panels of youth (46 vs. 46 and 230 cases vs. 413 controls, respectively) and a general population of youth, including 703 healthy subjects. RESULTS: One CpG site in the lymphocyte antigen 86 (LY86) gene, which showed higher methylation in the obese in both the initial (p = .009) and second genome-wide DNA methylation panel (p = .008), was further validated in both replication panels (meta p = .00016). Moreover, in the general population of youth, the methylation levels of this region were significantly correlated with adiposity indices (p ≤ .02), insulin resistance (p = .001), and inflammatory markers (p < .001). CONCLUSION: By focusing on recent GWAS findings in genome-wide methylation profiles, we identified a solid association between LY86 gene DNA methylation and obesity.

Dietary sodium, adiposity, and inflammation in healthy adolescents.

OBJECTIVES: To determine the relationships of sodium intake with adiposity and inflammation in healthy adolescents. METHODS: A cross-sectional study involved 766 healthy white and African American adolescents aged 14 to 18 years. Dietary sodium intake was estimated by 7-day 24-hour dietary recall. Percent body fat was measured by dual-energy x-ray absorptiometry. Subcutaneous abdominal adipose tissue and visceral adipose tissue were assessed using magnetic resonance imaging. Fasting blood samples were measured for leptin, adiponectin, C-reactive protein, tumor necrosis factor-α, and intercellular adhesion molecule-1. RESULTS: The average sodium intake was 3280 mg/day. Ninety-seven percent of our adolescents exceeded the American Heart Association recommendation for sodium intake. Multiple linear regressions revealed that dietary sodium intake was independently associated with body weight (ß = 0.23), BMI (ß = 0.23), waist circumference (ß = 0.23), percent body fat (ß = 0.17), fat mass (ß = 0.23), subcutaneous abdominal adipose tissue (ß = 0.25), leptin (ß = 0.20), and tumor necrosis factor-α (ß = 0.61; all Ps < .05). No relation was found between dietary sodium intake and visceral adipose tissue, skinfold thickness, adiponectin, C-reactive protein, or intercellular adhesion molecule-1. All the significant associations persisted after correction for multiple testing (all false discovery rates < 0.05). CONCLUSIONS: The mean sodium consumption of our adolescents is as high as that of adults and more than twice the daily intake recommended by the American Heart Association. High sodium intake is positively associated with adiposity and inflammation independent of total energy intake and sugar-sweetened soft drink consumption.

More physically active and leaner adolescents have higher energy intake.

OBJECTIVE: To test whether youths who engage in vigorous physical activity are more likely to have lean bodies while ingesting relatively large amounts of energy. For this purpose, we studied the associations of both physical activity and adiposity with energy intake in adolescents. STUDY DESIGN: The study subjects were adolescents who participated in 1 of 2 cross-sectional studies, the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study (n = 1450; mean age, 14.6 years) or the European Youth Heart Study (EYHS; n = 321; mean age, 15.6 years). Physical activity was measured by accelerometry, and energy intake was measured by 24-hour recall. In the HELENA study, body composition was assessed by 2 or more of the following methods: skinfold thickness, bioelectrical impedance analysis, plus dual-energy X-ray absorptiometry or air-displacement plethysmography in a subsample. In the EYHS, body composition was assessed by skinfold thickness. RESULTS: Fat mass was inversely associated with energy intake in both studies and using 4 different measurement methods (P ≤ .006). Overall, fat-free mass was positively associated with energy intake in both studies, yet the results were not consistent across measurement methods in the HELENA study. Vigorous physical activity in the HELENA study (P < .05) and moderate physical activity in the EYHS (P < .01) were positively associated with energy intake. Overall, results remained unchanged after adjustment for potential confounding factors, after mutual adjustment among the main exposures (physical activity and fat mass), and after the elimination of obese subjects, who might tend to underreport energy intake, from the analyses. CONCLUSION: Our data are consistent with the hypothesis that more physically active and leaner adolescents have higher energy intake than less active adolescents with larger amounts of fat mass.

How can we help people to develop lean and healthy bodies? A new perspective.

The dominant metabolic theory of obesity is that it develops from excessive positive energy balance. However, preventive interventions based on this theory have often been ineffective. This article proffers a developmental theory, which is based on recent epidemiologic research and a new line of research dealing with differentiation of immature stem cells into mature tissues. This theory posits that the mechanical stimulation provided by vigorous physical activity (PA) causes immature stem cells to differentiate into lean tissue cells rather than into fat cells. If this new theory is confirmed by future research, it implies that interventions that involve adequate doses of vigorous PA, along with appropriate diet composition, may be especially effective in promoting development of healthy bodies.

Association between self-reported sleep duration and dietary quality in European adolescents.

Evidence has grown supporting the role for short sleep duration as an independent risk factor for weight gain and obesity. The purpose of the present study was to examine the relationship between sleep duration and dietary quality in European adolescents. The sample consisted of 1522 adolescents (aged 12.5-17.5 years) participating in the European multi-centre cross-sectional 'Healthy Lifestyle in Europe by Nutrition in Adolescence' study. Sleep duration was estimated by a self-reported questionnaire. Dietary intake was assessed by two 24 h recalls. The Diet Quality Index for Adolescents with Meal index (DQI-AM) was used to calculate overall dietary quality, considering the components dietary equilibrium, dietary diversity, dietary quality and a meal index. An average sleep duration of ≥ 9 h was classified as optimal, between 8 and 9 h as borderline insufficient and < 8 h as insufficient. Sleep duration and the DQI-AM score were positively associated (ß = 0.027, r 0.130, P< 0.001). Adolescents with insufficient (62.05 (sd 14.18)) and borderline insufficient sleep (64.25 (sd 12.87)) scored lower on the DQI-AM than adolescents with an optimal sleep duration (64.57 (sd 12.39)) (P< 0.001; P= 0.018). The present study demonstrated in European adolescents that short sleep duration was associated with a lower dietary quality. This supports the hypothesis that the health consequences of insufficient sleep may be mediated by the relationship of insufficient sleep to poor dietary quality.