Multi-level influences on childhood obesity in Sweden: societal factors, parental determinants and child's lifestyle.

BACKGROUND: Swedish school children living in rural areas and in areas with low education are at excess risk of becoming overweight. This study examines influences of societal and individual characteristics (children and their parents) on prevalence of overweight and obesity, in a national sample of 7-9-year-old children. METHOD: Anthropometric and lifestyle data were collected in a nationally representative sample of 3636 Swedish children. Overweight and obesity (International Obesity Task Force (IOTF)) data were analyzed in relation to lifestyle factors, parental weight, education and breast-feeding. RESULTS: The prevalence of overweight was 15.6% including 2.6% obese. Urbanization level and parental characteristics (weight status and education) were related to risk of overweight. Overall less favorable lifestyle characteristics were observed in rural areas and for children of low/medium educated mothers. Boys had greater risk of obesity in semi-urban and rural areas but this was not true for girls. For children's overweight, the living area effect was attenuated in multivariate analysis, while there was an association with origin of parents, high parental weight and medium maternal education. For obesity, the living area effect remained in boys while having two non-Nordic parents predicted obesity in girls. Parental weight status was associated with obesity in both girls and boys. CONCLUSION: Individual and societal factors influence children's weight status, and parental weight status is a strong determinant. Including overweight and obese parents in future health promoting interventions could be a strategy to prevent children from becoming overweight, but identifying those parents may prove difficult. To ensure reaching children with the greatest needs, targeting high risk areas might be a more effective approach.

Food and nutrient intake, nutritional knowledge and diet-related attitudes in European adolescents.

BACKGROUND AND OBJECTIVE: To provide an overview of methods used to assess food and nutrient intake, nutritional knowledge and diet-related attitudes in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with selected results from the feasibility study. MATERIAL AND METHODS: To assess food intake in 13- to 16-year-old adolescents, a previously developed computer-assisted and self-administered 24-h recall was adapted for international use. Food consumption data were linked to national food composition databases to calculate energy and nutrient intakes. To assess nutritional knowledge in pupils not having any special (trained) education concerning 'nutrition', a 23-item validated multiple choice questionnaire was adapted. To assess eating attitudes, behaviour and/or putative problems with body weight in adolescents, a validated inventory covering 60 questions or statements was adapted for the study. In a feasibility study, instruments, data collection and processing were tested in one school class in each of the 10 participating European cities. RESULTS AND CONCLUSIONS: The feasibility study provided plausible results, quite consistent between countries. Against this background and for the first time, standardized and uniform methodology was made available for the main study to assess and characterize dietary intake, nutritional knowledge and eating attitudes.

Development and evaluation of a self-administered computerized 24-h dietary recall method for adolescents in Europe.

OBJECTIVE: To describe the development of a European computerized 24-h dietary recall method for adolescents, and to investigate the feasibility of self-administration (self report) by comparison with administration by a dietician (interview). METHODS: Two hundred and thirty-six adolescents (mean age 14.6 years (s.d.=1.7)) of eight European cities completed the 24-h recall (Young Adolescents Nutrition Assessment on Computer (YANA-C)) twice (once by self-report and once by interview). RESULTS: A small but significant underestimate in energy (61 (s.e.=31) kcal) and fat (4.2 (s.e.=1.7) g) intake was found in the self-reports in comparison with the interviews; no significant differences were found for the intake of carbohydrates, proteins, fibre, calcium, iron and ascorbic acid. Spearman's correlations were highly significant for all nutrients and energy ranging between 0.86 and 0.91. Agreement in categorizing the respondents as consumers and non-consumers for the 29 food groups was high (kappa statistics >or=0.73). Percentage omissions were on average 3.7%; percentage intrusions: 2.0%. Spearman's correlations between both modes were high for all food groups, for the total sample (>or=0.76) as well as for the consumers only (>or=0.72). Analysing the consumer only, on an average 54% of the consumed amounts were exactly the same; nevertheless, only for one group 'rice and pasta' a significant difference in consumption was found. CONCLUSION: Adaptation, translation and standardization of YANA-C make it possible to assess the dietary intake of adolescents in a broad international context. In general, good agreement between the administration modes was found, the latter offering significant potential for large-scale surveys where the amount of resources to gather data is limited.

Diurnal variation in postabsorptive resting metabolic rate and diet-induced thermogenesis.

Postabsorptive resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) were repeatedly assessed on different days in 10 young men of normal weight on mornings and afternoons. No significant diurnal variation was found in RMR, DIT, total postprandial substrate oxidation, and overall postprandial nutrient balances. The pattern of postprandial substrate oxidation indicated an increased glucose oxidation in the first hour after ingestion of a meal on morning tests compared with afternoon tests. This was probably related to differences in the degree of the postabsorptive state, ie, 12-14 h on morning tests and 6-7 h on afternoon tests.

Physical activity assessed by activity monitor and doubly labeled water in children.

PURPOSE: To validate the Computer Science and Application's (CSA) activity monitor for assessment of the total amount of physical activity during two school-weeks in 9-yr-old children and to develop equations to predict total energy expenditure (TEE) and activity energy expenditure (AEE) from activity counts and anthropometric variables. METHODS: A total of 26 children (15 boys and 11 girls, mean age 9.1 +/- 0.3 yr) were monitored for 14 consecutive days. TEE was simultaneously measured by the doubly labeled water method. Averaged activity counts (counts.min(-1)) were compared with data on: 1) TEE, 2) AEE = TEE minus basal metabolic rate (BMR; estimated from predictive equations), and 3) daily physical activity level (PAL = TEE/BMR). RESULTS: Physical activity determined by activity counts was significantly related to the data on energy expenditures: TEE (r = 0.39; P < 0.05), AEE (r = 0.54; P < 0.01), and PAL (r = 0.58; P < 0.01). Multiple stepwise regression analysis showed that TEE was significantly influenced by gender, body composition (body weight or fat free mass), and activity counts (R(2) = 0.54--0.60). AEE was significantly influenced by activity counts and gender (R(2) = 0.45). There were no significant differences between activity counts and PAL in discriminating among activity levels with "low" (PAL < 1.56), "moderate" (1.57 < or = PAL > or = 1.81), and "high" (PAL > 1.81) intensity. CONCLUSION: Activity counts from the CSA activity monitor seems to be a useful measure of the total amount of physical activity in 9-yr-old children. Activity counts contributed significantly to the explained variation in TEE and was the best predictor of AEE.

Lack of a systematic sustained effect of prolonged exercise bouts on resting metabolic rate in fasting subjects.

Resting metabolic rate (RMR) and respiratory quotient (RQ) were measured in nine young men of normal weight after an overnight fast on three occasions, twice with and once without exercise on the previous evening. Exercise was cycling for 90 min at 100 W or 175 W. A Latin-square experimental design was used to balance the order of treatment with the type of treatment. Energy expenditure was measured by indirect calorimetry using a ventilated hood system. No significant after-effect of exercise on RMR was found: on the 100 W treatment the RMR had decreased by 0.04 +/- 0.06 kJ/min from the control value (4.68 +/- 0.13 kJ/min), and after the 175 W treatment it had increased by 0.11 +/- 0.08 kJ/min. On the 175 W exercise treatment RQs decreased significantly from 0.85 +/- 0.01 (control) to 0.82 +/- 0.01 (P less than 0.05). This indicates that single bouts of prolonged exercise can have a persisting effect on the type of substrate oxidized in the fasting state.

Overweight and obesity in a representative sample of schoolchildren - exploring the urban-rural gradient in Sweden.

To present the prevalence and urban-rural differences of overweight and obesity in 7-9-year-old Swedish schoolchildren, we used anthropometric data from a nationally representative survey performed in 2008. Trained staff weighed and measured 4538 children in grades 1 and 2 in 94 primary schools. Weight classification was performed using the IOTF reference and school areas were classified based on level of urbanization and area-level education. Overweight was found in 17% of the children including 3% obese. For overweight, odds-ratios were 1.33 and 1.61 (significant) in semi-urban and rural areas, relative to urban areas. After adjusting for area-level education, differences by degree of urbanisation were greatly attenuated and non-significant. For obesity urban-rural differences were observed in boys only and remained after adjustment for area-level education. For area-level education, risk estimates were significantly elevated and unaffected by urbanization and gender, odds-ratios 1.75 and 2.21 for overweight and 2.62 and 3.69 for obesity, in medium- and low-education areas compared to high-education areas. This supports earlier reports identifying areas with low socioeconomic status as high-risk areas for overweight and obesity. However, this study also suggests that gender should be considered when targeting children in urban as well as rural communities for health promoting interventions.

Dietary energy density as a marker of dietary quality in Swedish children and adolescents: the European Youth Heart Study.

OBJECTIVE: To investigate if dietary energy density is associated with measures of dietary quality (food group, micronutrient and macronutrient intakes) in children and adolescents. SUBJECTS/METHODS: In all, 551 children (mean age 9.6 years, 52% girls) and 569 adolescents (15.5 years, 55% girls), sampled from schools in Sweden, completed a single 24-h dietary recall. Dietary energy density (kJ/g) was calculated as the energy from all food consumed divided by the weight of all food consumed. Beverages were excluded from the calculation. Food and micronutrient intakes were adjusted for energy intake. A one-way analysis of variance (ANOVA) was used to test for differences in food group and nutrient intakes across age- and gender-specific tertiles of energy density. Discriminant analysis was used to confirm the groupings formed by tertiles. RESULTS: Subjects with low-energy-density diets were significantly more likely to consume fruits, vegetables, pasta, rice, potatoes and cereals and less likely to consume sweetened drinks, sweets and chocolate. After energy adjustment, their intakes of many foods recommended in the Swedish food-based dietary guidelines were higher and intakes of nutrient-poor foods were lower. The macronutrient energy profile (% energy) of low-energy-density diets was closest to the recommended level. Low-energy-density diets contained greater amounts of most micronutrients. Discriminant analysis confirmed the existence of heterogeneous dietary patterns and the likelihood of correct classification by energy density in 65% of cases. CONCLUSIONS: Lower dietary energy density is associated with better dietary quality in children and adolescents. Energy density has advantages over other whole diet analysis methods and may be suitable as a simple proxy of diet quality.

Physical activity in relation to aerobic fitness and body fat in 14- to 15-year-old boys and girls.

The purpose of this study was to examine the strength of the relationship between different variables of physical activity and aerobic fitness and body fat in adolescent boys and girls. Activity energy expenditure (AEE), time spent in a sedentary state, and time spent engaged in moderate and vigorous physical activity (MVPA, > or = 50% peak oxygen uptake, VO2peak) were assessed by the minute-by-minute heart rate monitoring method in 82 randomly selected 14- to 15-year olds (42 boys, 40 girls). Body fat was determined by measuring skinfold thicknesses. VO2peak was measured by indirect calorimetry. Somatic maturity level was determined by percentages of adult (i.e. 18 years) height attained at examination. AEE was related to aerobic fitness for both genders (boys, r = 0.30, P = 0.056; girls, r = 0.45, P = 0.003). For boys, there was a significant relationship between maturity level and VO2peak (r = 0.48, P < 0.001). For both genders, body fat was significantly and negatively related to VO2peak (r = -0.48 and r = -0.43, P < 0.01). Body fat and maturity explained 47% of the variation in VO2peak in boys, whereas AEE and body fat explained 22% of the variation in VO2peak in girls. No significant associations between physical activity variables and the data on body fat were observed. The total amount of physical activity (AEE) was related to VO2peak, at least in adolescent girls. Although VO2peak seems to be influenced by the maturity level in adolescent boys, the data support the promotion of a daily active lifestyle among young people.

Heart rate as an indicator of the intensity of physical activity in human adolescents.

The aims of this study were, in a group of adolescents, firstly to identify the absolute heart rates (HR) and the percentages of maximal heart rates (HRmax) corresponding to 40%, 60% and 80% of peak oxygen uptake (PVO2), secondly to identify absolute and relative (%PVO2) oxygen uptakes (VO2) corresponding to HR of 120, 140 and 160 beats.min-1, and thirdly to examine a possible effect of fatness and fitness on the relationship between HR and VO2. The subjects were 127 (60 boys, 67 girls) adolescents with a mean age of 14.8 (SD 0.3) years. The HR and VO2 were measured by means of an incremental exercise test to exhaustion. Linear regressions were performed for the HR-VO2 and VO2-HR relationships using absolute and relative (%HRmax, %PVO2) data for each individual. From these regressions, target HR and VO2 were computed. Average target HR corresponding to 40%, 60% and 80% of PVO2 were: 119 (SD 9), 145 (SD 9), 171 (SD 8), and 120 (SD 10), 146 (SD 8), 172 (SD 8) beats.min-1 for boys and girls, respectively. Average VO2 corresponding to HR of 120, 140 and 160 beats.min-1 were: 22 (SD 5), 30 (SD 5), 38 (SD 6) and 18 (SD 4), 24 (SD 4), 31 (SD 4) mlO2.kg-1.min-1 for boys and girls, respectively. An analysis of covariance showed a significant fitness effect (P < 0.001) for predicted VO2 at all HR studied. The results suggest that the use of absolute HR to define exercise intensity levels when assessing young people's physical activity using HR monitoring detracts from the validity of the interpretation of the data.

Diet and physical activity--interactions for health; public health nutrition in the European perspective.

For the majority of European adults, who neither smoke nor drink excessively, the most significant controllable risk factors affecting their long-term health are what they eat, and how physically active they are. Scientists are supposed to clarify to policy makers and health professionals the usefulness of their health messages. However, to be able to do that, a more detailed understanding is needed of the basic mechanisms behind the effects on health of diet and physical activity and, especially, the two in combination. Further, better methods for assessment of nutrition and physical activity in the population have to be developed, and more and better baseline data have to be collected. Increased and more efficient interventions are then needed. People trained and competent in the new discipline of Public Health Nutrition are required. Through the stimulating support that the European Commission, as well as other national and international partners, are presently giving to the development of Public Health Nutrition across Europe, we can hope for an increased mobility, networking and understanding between European nutrition and physical activity professionals. This will most likely result in greater and better policy making, strategy development, implementation and evaluation. We now have a great possibility to develop the integrated field of preventive nutrition and health enhancing physical activity.