In epidemiologic research, the recent increase in childhood obesity worldwide is mostly attributed to environmental,

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1 Research Brief Relationship between Eating Behavior, Breakfast Consumption, and Obesity Among Finnish and Greek Adolescents Alexandra Veltsista, MD, MS 1 ; Jaana Laitinen, PhD 2 ; Ulla Sovio, MS, PhD 3 ; Eleftheria Roma, MD, PhD 1 ; Marjo-Ritta Järvelin, MD, PhD 3,4 ; Chryssa Bakoula, MD, PhD 1 ABSTRACT Objective: To investigate the relationship between eating-related behaviors, particularly breakfast consumption, and weight status in Finnish and Greek adolescents. Methods: A total of 6, year-old Finnish adolescents and 2, and 18-year-old Greek adolescents, based on the latest follow-up of 2 population-based cohorts, were studied. Univariate analysis examined the associations between breakfast consumption, family meals, emotional eating, bingeing, and weight status in both populations. Multiple logistic regression models focused on the relationship between breakfast consumption and overweight/obesity taking potential confounders into account. Results: Daily breakfast consumption was associated with lower levels of overweight/obesity among Finnish and Greek boys, but not among girls. Adjusting for confounders did not change the result among Greek boys, but adjustment for father s body mass index, weight control, and fear of getting fat attenuated the association among Finnish boys. Conclusions and Implications: This study highlights the importance of breakfast consumption, particularly among male adolescents, in obesity prevention programs. Key Words: obesity, eating behavior, breakfast, cohort studies, adolescent (J Nutr Educ Behav. 2010;42: ) INTRODUCTION The prevalence of childhood and adolescent obesity is increasing rapidly throughout the world, but great regional differences exist. 1 In Europe, there is a tendency for a higher prevalence of overweight youth (up to 23%) in southwestern countries, including Greece, whereas in the Nordic countries, including Finland, the corresponding prevalence is less than 15%. 1 To clarify why regional differences exist, cross-national comparisons using nationally representative samples and the same procedures are required. 1 This survey, based on the European Birth and Lifecourse Study (EURO- BLCS), was specifically designed for comparisons, using the same methodology and classification procedures. 2 In epidemiologic research, the recent increase in childhood obesity worldwide is mostly attributed to environmental, rather than genetic factors. 3-5 Numerous studies indicate positive associations between body weight and eating-related behaviors, including skipping breakfast, 6,7 emotional eating, 8 binge eating, 9,10 and family meals. 11,12 Culture and socioeconomic status play an important role in the development of eating behaviors This cross-national comparison aimed to reveal similarities and differences in weight status and eatingrelated habits among adolescents of a northern (Finland) and a southern (Greece) European country with distinct cultural, habitual, social, and geographical characteristics. Relationships between eating-related habits and weight status were examined, focusing on the association between daily breakfast consumption and levels of overweight and obesity in each country. METHODS 1 1st Department of Pediatrics, Aghia Sofia Children s Hospital, University of Athens, Athens, Greece 2 Oulu Regional Institute of Occupational Health, Oulu, Finland 3 Department of Epidemiology and Public Health, Imperial College London, UK 4 Department of Public Health and General Practice, University of Oulu, Finland Address for correspondence: Alexandra Veltsista, MD, MS, 1st Department of Pediatrics, University of Athens, Aghia Sophia Children s Hospital, Thivon and Levadias Streets, Athens, Greece; Tel: (0030) ; Fax: (0030) ; alexveltsista@in.gr Ó2010 SOCIETY FOR NUTRITION EDUCATION doi: /j.jneb This cross-national study is based on the most recent follow-up of 2 birth cohorts, namely, the Northern Finland 1985/86 birth cohort and the Greek 1983 birth cohort, conducted in The latest follow-up was part of the EURO-BLCS project. 2 One of the main undertakings of this project was to harmonize methods of data collection between the countries involved. 2 Journal of Nutrition Education and Behavior Volume 42, Number 6,

2 418 Veltsista et al Journal of Nutrition Education and Behavior Volume 42, Number 6, 2010 The Greek population consisted of 17- to 18- year-old adolescents born throughout Greece in April Participants initially represented 8% of the country s annual births and constituted a representative, populationbased sample. In 2001, attempts were made to locate the participants through the country s high schools. Participants and their parents were sent anonymous questionnaires, as required by the Ministry of Education, which issues the permission for conducting research in schools. A total of 4,675 adolescent and parental questionnaires were administered, of which 3,500 were returned (74.8%), and 3,452 (73.8%) gave permission to use their data. Details of the study design, methodology, and data collection have been given elsewhere. 16,17 The procedures for the Greek data collection were approved by the National Hellenic Research Foundation, the Institute of Biological Research and Biotechnology, and the National Privacy Principles Board. Sensitivity analysis showed that the data collected in 2001 was fairly well representative of the initial birth cohort. 17 Furthermore, participants recruited in 2001 were representative of adolescents living throughout Greece based on the gender, urban living, and socioeconomic distribution of the same year s census. The Finnish cohort comprised 9,432 live-born children in the 2 northernmost provinces of Finland born between July 1, 1985 and June 30, A more detailed description of the cohort and early data collection has been given. 17,18 A total of 9,215 adolescents of the original study were still alive and living in Finland with a known address in Questionnaires were distributed by mail to traced adolescent cohort members and their parents. Data collection was started at the end of May 2001 and continued until spring Therefore, the average age of the participants was very close to 16 years. In all, 7,344 (80%) adolescents originally returned the questionnaire, of whom 7,128 (77.4%) allowed their data to be used in epidemiological studies. The Finnish study was approved by the Ethical Committee of the University of Oulu, Finland. When the authors compared the background factors of the Finnish participants in 2001 to the children of the initial birth cohort, they detected the data collected in 2001 was fairly representative of the initial Northern Finland birth cohort. 17 In addition, the sample size was large, and the response rates were high. Therefore, the sample could be considered representative of adolescents living in northern Finland. Variables and Statistical Analyses Body mass index (BMI) was calculated from self-reported weight and height obtained from the questionnaires. Overweight and obesity were defined by using the age- and sex-specific BMI cutoff points proposed by the International Obesity Task Force. 19 Breakfast consumption was derived from a question assessing the frequency of eating breakfast during the previous year, with 4 possible answers: daily, 1-3 times per week, 1-3 times per month, and never/ rarely. The last 3 responses were grouped together. The frequency of having family meals was requested, and the answers a few times per week, 1-2 times per week, occasionally, and hardly ever were grouped together, leaving daily/almost daily as a single group. The use of weight control methods was assessed through a question with 4 options: dieting/fasting, heavy exercise, vomiting, or use of medication and their frequency ( never, occasionally, or often ). The use of at least 1 of the above methods, either occasionally or often, formed the extreme weight control practices group. Emotional eating was studied by asking participants whether they tried to make themselves feel better by eating when facing a stressful situation. The possible answers were never, sometimes, quite often, and very often. The last 2 responses were grouped together. 8 The authors asked about the frequency of bingeing on large amounts of food and grouped together the following answers: (1) never and hardly ever ; (2) occasionally and once per month ; (3) once per week, 2-3 times per week, and daily. The question: Are you afraid of the idea of getting fat? was asked, with 2 possible answers, yes and no. Parental BMIs were determined from self-reported weight and height measurements in the parental questionnaire, whereas socioeconomic status (SES) was based on the father s occupation. Analysis was restricted to those who had valid self-reported weight and height measurements (6,468 Finns and 2,842 Greeks). The authors calculated the prevalence of eatingrelated behaviors, weight status, and other study items separately for Finnish and Greek boys and girls. The authors then compared Greeks and Finns by gender by calculating prevalence ratios and their 95% confidence intervals. To focus on the relationship between breakfast consumption and weight status, the authors used univariate logistic regression to examine the odds for boys and girls separately in both populations. The authors then examined the association of potential confounders with breakfast consumption and weight status, and adjusted the multivariate logistic regression analysis only for the confounders significantly associated with both outcome (ie, overweight/ obesity) and independent variable (ie, breakfast consumption). From the potential confounders examined (afraid of getting fat, weight control, emotional eating, bingeing, parents BMI, and SES), the following were controlled for in multivariate analysis: weight control, fear of getting fat, parents BMI, and SES. Odds ratios with 95% confidence intervals were reported for unadjusted and adjusted models. RESULTS Comparison of the prevalence of overweight and obesity, eating-related behaviors, and psychosocial factors between Greeks and Finns by sex is presented in Table 1. Greek boys showed a higher prevalence of overweight compared to Finns, but they had very similar levels of obesity. In girls, overweight was similar in both cohorts, but obesity was significantly lower in Greek girls. Nearly 75% of Finnish boys and 61.6% of Finnish girls had breakfast daily, but the

3 Journal of Nutrition Education and Behavior Volume 42, Number 6, 2010 Veltsista et al 419 Table 1. Frequency of Overweight/Obesity and Eating-related Behaviors Among Finnish and Greek Adolescents Boys Girls Finnish, % (n ¼ 3,110) Greek, % (n ¼ 1,291) Greek/Finnish, PR (95% CI) Finnish, % (n ¼ 3,358) Greek, % (n ¼ 1,551) Greek/Finnish, PR (95% CI) BMI Normal weight ( ) ( ) Overweight ( ) ( ) Obese ( ) ( ) Daily breakfast ( ) ( ) Fear of becoming fat ( ) ( ) Daily/almost daily family meals ( ) ( ) Any weight control ( ) ( ) Bingeing on food Never/hardly ever ( ) ( ) Occasionally ( ) ( ) At least once/wk ( ) ( ) Emotional eating Never ( ) ( ) Sometimes ( ) ( ) Quite/very often ( ) ( ) BMI indicates body mass index; CI, confidence interval; PR, prevalence ratio; wk, week. percentage among Greeks was less than 50%. The associations between eating behaviors, psychosocial factors, and weight status were stratified by gender and cohort. Among boys, daily breakfast consumption was inversely associated with weight status in both cohorts (P <.001 for Greeks and Finns), but no association was found among girls. Fear of getting fat was positively associated with weight status among Finnish and Greek boys (P <.001 for Finnish boys and P ¼.001 for Greek boys), but not among girls. A significant association was also found between extreme weight control practices and weight status for adolescents in both cohorts (P <.001 for all). Emotional eating and parental BMI were positively associated with weight status in all strata (P #.007 for all), but there were no differences in the frequency of family meals and bingeing by weight status in any strata (data not shown). The results of the association between breakfast consumption and weight status are presented in Table 2. The odds of overweight/obesity were 40% lower in Finnish and 30% lower in Greek boys who had a daily breakfast compared to those who did not. Among girls, no significant associations were found. Adjusting for confounders did not change the result among Greek boys, but among Finnish boys it attenuated the effect to the same level with Greek Table 2. Odds Ratios and 95% Confidence Intervals of Overweight/Obesity by Breakfast and Confounding Factors From Logistic Regression Among Finnish and Greek Adolescents Boys Girls Finnish (n ¼ 2,002) Greek (n ¼ 1,045) Finnish (n ¼ 2,221) Greek (n ¼ 1,272) Unadjusted Daily breakfast 0.60 ( ) 0.71 ( ) 0.84 ( ) 0.98 ( ) Adjusted a Daily breakfast 0.72 ( ) 0.73 ( ) 1.01 ( ) 1.07 ( ) Weight control 2.61 ( ) 2.29 ( ) 1.73 ( ) 3.02 ( ) Fear of becoming fat 1.93 ( ) 1.67 ( ) 1.56 ( ) 1.18 ( ) Mother s BMI (kg/m 2 ) 1.08 ( ) 1.05 ( ) 1.14 ( ) 1.13 ( ) Father s BMI (kg/m 2 ) 1.09 ( ) 1.14 ( ) 1.10 ( ) 1.08 ( ) BMI indicates body mass index. a Adjusted for socioeconomic status.

4 420 Veltsista et al Journal of Nutrition Education and Behavior Volume 42, Number 6, 2010 boys. From step-by-step analyses (data not shown), the authors saw that this result was owing to adjustment for father s BMI, weight control, and fear of getting fat, which suggests these variables are not independent of the breakfast consumption variable. DISCUSSION The present study confirmed higher levels of overweight youth in Greece compared to those in Finland, and a higher level of daily breakfast consumption among the Finns than among the Greeks These differences can be attributed to a number of factors that interact: individual (such as biological and psychological), social (such as family and peers), environmental (such a school and fast-food outlets), and societal (such as mass media and social and cultural norms). 24 Daily breakfast consumption was associated with a lower level of overweight/obesity among boys in both cohorts, but no association was found among girls. This finding is in accordance with results from previous research with adolescent American children. 25 Conversely, others found breakfast consumption to be significantly associated with overweight in girls. 26,27 These discrepancies may be partly owing to differences in the ages of the youth studied, definitions of breakfast skipping, classification system used to determine overweight in youth, and controlling for baseline BMI, or other potential confounders. 27,28 Other possible explanations may relate to type of food consumed or engagement in various unhealthful behaviors, 14,29,30 which have been shown to be associated with skipping breakfast. Further research on these issues is needed. The finding that father s BMI, weight control, and fear of getting fat partially mediated the association of breakfast consumption and overweight in Finnish adolescent boys, but not in Greeks, suggests that cultural differences are likely to interfere. Thus, public health professionals may need to take cultural differences into account before proposing preventive approaches or activities to improve adolescent weight status. This study is limited in that there was an age difference between the populations studied, the influence of which could not be determined. However, the present findings on the prevalence of overweight/obesity and breakfast consumption in both countries correspond fairly well to previous study values Second, BMI was based on self-reported measures of weight and height, but comparison with clinical measurements among the Finns showed these estimations were valid. 31 Third, breakfast consumption was determined by a nonstandardized, self-reported measure. To overcome this problem, the definition criterion of breakfast consumption was restrictive, including only those who reported daily consumption. Finally, the observed associations between eating breakfast, other lifestyle variables, and overweight/ obesity were based on data from cross-sectional studies with the consequence that the direction of these relations cannot be implied. IMPLICATIONS FOR RESEARCH AND PRACTICE This study is unique because the authors have been able to make use of 2 large population-based cohorts from a northern and a southern European country, with harmonized methods of data collection in the latest follow-up, to determine obesity risk factors among adolescents. It was found that, independently of a range of covariates, breakfast skipping was associated to overweight/ obesity in boys from both nations. Although breakfast consumption was not significantly associated with weight status in girls, a large body of research indicates that breakfast eaters benefit from improved nutrient intake, behavior, and academic performance. 28,32 A high priority for the future should be to further examine the associations between breakfast and obesity by gender, crossnationally, against other potential confounders such as type of food consumed for breakfast, and other unhealthful behaviors. Further research with representative populations of adolescents of the same age from both countries, as well as longitudinal analysis of the associations examined here, are also warranted. ACKNOWLEDGMENTS Funded by the European Commission Quality of Life and Management of Living Resources Program (contract number QLG1-CT ). The Greek Birth Cohort study was further supported by the Academy of Athens and the Northern Finland Birth Cohort study by the Academy of Finland. REFERENCES 1. 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