Prevalence of overweight and obesity among adolescents in Poland

INTRODUCTION

Childhood obesity is a public health problem in many countries [1]. During the last decades, obesity rates have increased in Europe, especially in eastern European countries, where the obesity rate was relatively low at the beginning of this century, while in other countries this problem has stabilised [2]. Childhood obesity can cause many health problems; it undermines the social, physical, and psychological well-being, and is a risk factor for other noncommunicable diseases [3]. Childhood obesity determines obesity in adulthood [4]. Moreover, obesity treatment is very expensive, and the results of prevention programs do not always confirm their effectiveness [5]. In Poland, obesity is already diagnosed among toddlers [6]. The prevalence of overweight and obesity among adolescents indicates that the problem of excessive weight concerns at least every fifth teenager, but data vary depending on age and gender [7]. The latest data showed a favourable downward trend, which according to the authors of the Polish report [8], should be associated with observed favourable changes in health behaviours, including improved physical activity among adolescents. On the other hand, it is worth noting that the data collected in that project are based on self-reported height and weight values. For this reason, the data may be less reliable compared to similar studies, in which participants are accurately measured.

MATERIAL AND METHODS

GENERAL INFORMATION

The study was conducted from October 2013 to March 2014 as part of the research and education program “Wise Nutrition – Healthy Generation” (WN-HG project). The scope of the program included performing anthropometric measurements to assess the nutritional status, as well as evaluation of selected dietary behaviours and parameters related to the physical activity of students. In this article we present the results of weight-related studies only. The WN-HG project diagram is presented in Figure 1.

STUDY PARTICIPANTS

Participants of both genders (13-19 years old, n = 14,044 students) were recruited from 207 randomly selected schools. The information about the possibility of joining the program was sent to all schools listed in the electronic register of schools of the Minister for National Education in Poland (over 14,000 schools). In total 2,058 schools joined the program (10% of all schools in Poland), and 207 schools were randomly selected for the research part of the program. Sampling was stratified by province and location (large, medium, small city) as well as the type of school (secondary and upper secondary). In the next step, students were randomly selected from the class registry. All of the students’ data have been fully anonymised. Schools and students included in the research are from all over the country; therefore, the study can be considered as nationwide. The study was conducted among a group of healthy adolescents. Exclusion criteria for students were as follows: age < 13 years old or age > 19 years old, unhealthy adolescents, pregnancy and lactation in girls, persons with posture defect/disability that prevents anthropometric measurements, and lack of consent to participate in the study. Exclusion criteria for schools were as follows: no application to the WH-NH program and lack of consent to participate in the study. Figure 1 presents the WN-HG project diagram, including a scheme for selecting the sample of the study.

MEASUREMENTS

Anthropometric measurements, such as weight and height, were conducted by trained dietitians. All measurements were carried out with equipment provided by the Polish Society of Dietetics: digital floor scales (TANITA HD-380 BK, Tanita Corporation, Tokyo, Japan) and an elastic measuring tape (0-200 cm). All dieticians conducting the measurements followed the same standardised protocol. All the measurements were done according to the Anthropometry Procedures Manual by the National Health and Nutrition Examination Survey (NHANES) [9]. The weight of the individuals was measured to the nearest 0.1 kilogram twice, and the mean value was recorded. Measurements were made for individuals dressed in basic cloths (e.g. underwear, trousers/skirt and t-shirt) and without shoes. From the final result, 0.5 kg was subtracted (predicted weight of the basic clothes). For the height measurement, individuals stood on a flat surface in an upright position with their back against the wall, their heels together, and toes apart (without shoes and socks). The students were asked to stand as tall as possible with the head in the Frankfort horizontal plane. The height measurement, to the nearest 0.1 cm, was performed twice, and the mean value was recorded.
Body height and weight were measured to calculate the body mass index (BMI). BMI was calculated as body weight in kilograms divided by the square of height in metres. Depending on the age of the students, different criteria for assessing the weight status were used. Body weight of students aged 13-18 years old was assessed using international BMI standards for young people, adopted by the International Obesity Task Force (the IOTF BMI cut-off points) criteria [10]. For students at the age of 19 years, the standard WHO BMI criteria for adults were applied [11]. Separate terms for overweight and obesity were used, whereas the term „excessive weight” included overweight and obesity.
All the dieticians had been trained before the measurement. The program was carried out following the standards required by the Helsinki Declaration and was approved by the Scientific Committee of the Polish Society of Dietetics. All parents received written information describing the program. After study approval from the Society of Dietetics and the Warsaw University of Life Sciences Institutional Review Board, consent was obtained from schools’ directors and parents of adolescents.

STATISTICAL METHODS

Statistical data processing was performed using Statistica StatSoft version 13.1. All data were analysed in the total group, as well as in age and gender subgroups. Anthropometric data including weight, height, and BMI were presented as means with standard deviations (SDs). The weight status was presented as the prevalence of underweight, normal weight, overweight, and obesity (expressed as the number of students and percentage of subjects in every age group, among all girls and all boys). A comparison of BMI vs age and gender was made with an analysis of the variance; qualitative variables were determined using Pearson’s χ2 test. Additionally, the contingency coefficient or Cramér’s V was used to indicate the strength of association between categorical variables. The differences were considered significant at p < 0.05.

RESULTS

The total sample group consisted of 14,044 students, including 7,553 girls and 6,491 boys. Anthropometric characteristics of Polish adolescents divided by gender (all girls vs all boys) are presented in Table 1. The differences in BMI depending on gender are also indicated in Table 1. The weight status of Polish adolescents in total and divided by age is presented in Figure 2.
More than 3/4 of the study population had normal weight (76.7%), 5.1% of the subjects were underweight, and excessive weight was observed in 18.2% of adolescents (overweight in 11.6% and obesity in 6.6%). Significant correlations were found between the weight status of the students and their age (p = 0.0000). However, the value of the Cramér coefficient (0.07) indicated a small influence of age on the weight status in the total group. There was an increase in the prevalence of underweight with age, while the prevalence of obesity declined with age. Normal body weight was the most common among 16-year-olds, and this age category included the fewest overweight students. The occurrence of overweight was most frequent among border age groups, i.e. 13- and 19-year-olds. Obesity was most common among 13-year-olds.
The weight status of the individuals, including prevalence of overweight and obesity (separately) divided by age and gender, is presented in Table 2.
Analysis of the weight status in the gender subgroups (girls and boys separately) also showed a significant relationship with age (p = 0.0000 in both groups). However, the strength of these effects was small (V Cramér = 0.09 in girls and 0.08 in boys). Among the girls, the prevalence of underweight increased with age from 2.84% for 13-year-olds to 10.53 for 19-year-olds. The highest rate of underweight (12.4%) was found among 18-year-old girls. Among the boys, underweight was most commonly observed in the oldest age group, while it was the least common among 15-year-olds. The highest proportion of adolescents with a normal weight was found among 15-year-old girls and 16-year-old boys. The prevalence of overweight among girls was similar in all age groups, whereas the difference in boys was noticeable: 9.39% for the 16-year-old group and 17.04% for the 18-year-old group. The obesity rate was higher for younger individuals in both gender groups, and a decreasing prevalence with age was observed. The highest percentage of obesity was noted for the group of the youngest boys (13 years old).

DISCUSSION

Adequate growth and normal body weight of children are the basic indicators of their general health. In daily practice, basic anthropometric tests, such as the assessment of length/height and weight, are the most important tools for physicians to evaluate the growth status of the child. Incorrect weight status might be a sign of some diseases and nutrition-related problems. Early detection of such abnormalities allows for early intervention. On the other hand, the monitoring of anthropometric data is a public health tool to summarise and compare data in time and among groups of children. Nevertheless, comparing data is often problematic due to the different methodologies used. In recent years, there have been several international studies in which data were collected according to the same protocol of study, but in some other studies the data were self-reported. The data presented in this article were obtained during measurements conducted by trained specialists; therefore, it should be considered as reliable. The data concerning anthropometric measurements such as height, weight, and BMI showed diversity according to age and gender. Similar values for growth, body weight, and the mean values of BMI were found in previous Polish studies among a group of children and adolescents in 2007-2009 [12, 13], but we found a lower proportion of overweight children, and a higher proportion of children with obesity compared to previous studies [12]. Another Polish study [14], which examined the prevalence of overweight and obesity among adolescents aged 13-15 years in 2005, reported a lower percentage of adolescents with overweight and obesity in both genders. The two studies mentioned above present the results of research conducted in the last decade, which was a time of economic transformation in Poland. The international report from the Health Behaviour in School-aged Children (HBSC) study showed that from 2002 to 2010, in Poland, there was a rapid increase in the number of adolescents with excessive body weight [15]. At that time, the number of children with excessive body weight doubled. The rate of weight gain has been characterised as one of the highest in the studied groups of countries. A similar increase in the number of overweight children was also noted in other countries (e.g. Ukraine, Russia, Latvia, and Estonia), but in these cases the prevalence of excessive weight in 2010 was not as high as in Poland [16]. The authors of that study noted that the overweight prevalence increased significantly in at least half of the surveyed countries, and they showed that in 2010 the prevalence of overweight was highest in the USA (about 29% of adolescents) and lowest in Ukraine (about 10% of adolescents). A relatively high prevalence of overweight in 2010 among adolescents was noted in Greece and Canada, but in both cases the prevalence of overweight was also high in 2002 [16].
Many authors showed that the prevalence of overweight and obesity in adolescents worldwide is high and varies according to age, as well as gender (higher among boys [17]). In the Polish study [13], authors evaluating a 10-year trend (from 1998 to 2008) showed a trend toward stabilisation of the prevalence of overweight and obesity among school children. Some differences have been shown after age and gender adjustment. The authors noted a declining obesity prevalence among girls (from 10.1% to 7.7%) and increased prevalence of overweight among boys (from 10.5% to 14.2%). The same authors indicated that the proportion of overweight boys in 2008 was significantly higher than in 1998 due to a significant increase in the prevalence of overweight among seven- and eight-year-olds. The results of our study also confirmed the higher prevalence of obesity in the group of younger boys compared to other specific age groups and the all-ages group of girls. Similar observations were recorded in the last two editions of the Polish HBSC study [8, 15]. A significant correlation between age and gender was observed in the Russia study [16]. The above results indicate an increasing trend of prevalence of excessive body weight among younger boys (11-year-olds) compared to the oldest (15-year-olds). Higher rates of obesity among boys aged 3-17 years old compared to girls have been noted in the three latest decades in the United States, England, and France [1]. Other authors estimating trends in the prevalence of overweight and obesity in the US among children and adolescents showed significant differences according to age and gender [18]. The same authors noted that between 2011 and 2014 in US, for children and adolescents aged 2-19 years old, the prevalence of only obesity was 17%, and extreme obesity 5.8%. In England, childhood overweight and obesity prevalence noted in 2013/2014 ranged from 22.5% to 33.5%, and varied according to age, gender, and other factors [19]. In the case of France, the obesity rate was lower than in other countries and results showed a general stabilisation. The authors explained that the stabilisation of prevalence of overweight and obesity in France is caused by the introduction of obesity prevention programs focused on children [20]. The effectiveness of educational programs on obesity prevention among children implemented in different countries has been demonstrated in many studies [19, 21-23], but there were programs with limited success in improving healthy eating behaviours and physical activity among students [24]. Some authors indicate that in the prevention of obesity among children, we need to develop a new concept of a community-based incentive [25]. In the last decade, several obesity prevention programs were also implemented in Poland, some of which were dedicated to the youngest age group [26]. A number of authors point out that due to these programs, there is a relative stabilisation in weight-gain trends among children in Poland [8].
In recent years, no research on such a scale has been conducted in Poland, and what is more all data presented in our study were obtained from measurements. The previously published research, despite its national character, was based on students’ self-reported data on height and weight. The authors of these studies pointed out that self-reported data generally lead to an underestimation of BMI, especially among girls and among overweight and obese adolescents. Because BMI does not measure body fat tissue directly, its use as a diagnostic tool is limited, but it might be considered as an appropriate screening tool.

CONCLUSIONS

In conclusion, the prevalence of overweight and obesity among adolescents in Poland is on an average level for Europe but is still relatively high compared to other countries. The prevalence of obesity among children in Poland is not a problem only of the last decade, although the highest rate in the growth of this condition among adolescents was recorded in that time. To counteract this phenomenon in Poland, in 2007 a National Program was introduced for the prevention of overweight, obesity, and chronic non-infectious diseases through improved nutrition and physical activity for 2007-2011 [27] based on the WHO strategy [28]. Obesity prevention programs implemented in Poland focus on different age groups, including adolescents. Such activities incorporate education on healthy lifestyle, as well as improvement of physical activity. However, the effects of these activities are not always evaluated. Anthropometric measurements are important elements of the efficacy evaluation. In order to be reliable and comparable to data from other countries, anthropometric measurements should be made using international standards, and the results should refer to them.
In order to create effective preventive programs to limit the increase in childhood obesity, special emphasis should be placed on screening for abnormal weight and unhealthy lifestyle, including eating habits. Such activities should be carried out in children from the youngest age groups. All children diagnosed and classified as at risk should be covered by special medical assistance and individual dietary counselling. If necessary, the intervention should also include the help of a physiotherapist or psychologist. The child’s parents should also participate in the implementation of such activities.

ACKNOWLEDGMENTS

Parts of this program were presented as a poster presentation titled Prevalence of overweight and obesity among youth in Poland – results of “Wise Nutrition – Healthy Generation” at the DIETS-EFAD Conference, Athens, Greece, 9-12 October 2014. The program WN-HG was describe in Polish in Dietetyka (the official journal of the Polish Society of Dietetics) [29].
The authors would like to express their gratitude to all the participants of the program. We would also like to thank Professor Jadwiga Hamułka and Professor Agata Wawrzyniak (Department of Human Nutrition, Institute of Human Nutrition Sciences WULS-SGGW, Warsaw, Poland) for their help in the preparation and the conduction of the training for dieticians. We would like to thank Professor Ewa Lange (Department of Dietetics, Institute of Human Nutrition Sciences, WULS-SGGW, Warsaw, Poland) for her help in the preparation of dietary counselling materials. We would like also to thank psychologist MSc. Bianca-Beata Kotoro for her support. Thanks also go to all of the dieticians, directors, and school teachers.

FUNDING

The program “Wise Nutrition – Healthy Generation” was granted by the Coca-Cola Foundation.

DISCLOSURE

The authors report no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; and in the decision to publish the results.

References

1. Obesity Update 2017. Available from: https://www.oecd.org/els/health-systems/Obesity-Update-2017.pdf (accessed: 10 October 2019).
2. Inchley J, Currie D, Jewell J, et al. (eds). Adolescent obesity and related behaviours: trends and inequalities in the WHO European Region, 2002–2014. Observations from the Health Behaviour in School-aged Children (HBSC) WHO collaborative cross-national study. 2017. Available from: http://www.euro.who.int/__data/assets/pdf_file/0019/339211/WHO_ObesityReport_2017_v3.pdf (accessed: 10 October 2019).
3. Report of the Commission on Ending Childhood Obesity. Implementation plan: executive summary. World Health Organization, Geneva 2017 (WHO/NMH/PND/ECHO/17.1). Licence: CC BY-NC-SA 3.0 IGO. Available from: http://apps.who.int/iris/bitstream/10665/259349/1/WHO-NMH-PND-ECHO-17.1-eng.pdf (accessed: 10 October 2019).
4. Mamun AA, O’Callaghan MJ, Cramb SM, et al. Childhood behavioral problems predict young adults’ BMI and obesity: evidence from a birth cohort study. Obesity (Silver Spring) 2009; 17 (4): 761-766.
5. Wang Y, Cai L, Wu Y, et al. What childhood obesity prevention programmes work? A systematic review and meta-analysis. Obes Rev 2015; 16 (7): 547-565.
6. Weker H, Barańska M, Riahi A, et al. Nutrition of infants and young children in Poland – PITNUTS 2016. Dev Period Med 2017; 21 (1): 13-28.
7. Inchley J, Currie D, Young T, et al. (eds.). Health Policy For Children And Adolescents, No. 7 Growing up unequal: gender and socioeconomic differences in young people’s health and well-being. Health Behaviour In School-Aged Children (HBSC) Study: International Report From The 2013/2014 Survey. WHO Regional Office for Europe, Copenhagen 2016. Available from: http://www.euro.who.int/__data/assets/pdf_file/0003/303438/HSBC-No.7-Growing-up-unequal-Full-Report.pdf?ua (accessed: 10 October 2019).
8. Mazur J (ed.). Zdrowie i zachowania zdrowotne młodzieży szkolnej w Polsce na tle wybranych uwarunkowań socjodemograficznych. Wyniki badań HBSC 2014 [Health status and behaviours od school children in Poland on the background of sociodemographic conditions. Results from the HBSC 2014]. Instytut Matki i Dziecka, Warszawa 2015.
9. National Health and Nutrition Examination Survey (NHANES). Anthropometry Procedures Manual. January 2007. Available from: https://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/manual_an.pdf (accessed: 10 October 2019).
10. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000; 320 (7244): 1240-1245.
11. World Health Organization. Body mass index – BMI. Available from: http://www.euro.who.int/en/health-topics/disease-prevention/nutrition/a-healthy-lifestyle/body-mass-index-bmi (accessed: 10 October 2019).
12. Kułaga Z, Litwin M, Tkaczyk M, et al. Polish 2010 growth references for school-aged children and adolescents. Eur J Pediatr 2011; 170 (5): 599-609.
13. Mazur A, Klimek K, Telega G, et al. Ten-year secular trend of overweight and obesity in school children in south-eastern Poland. Ann Agr Env Med 2014; 21 (3): 634-638.
14. Jodkowska M, Oblacińska A, Tabak I. Overweight and obesity among adolescents in Poland: gender and regional differences. Public Health Nutr 2010; 13 (10A): 1688-1692.
15. Currie C, Zanotti C, Morgan A, et al. (eds.). Social determinants of health and well-being among young people. Health Behaviour in School-aged Children (HBSC) study: international report from the 2009/2010 survey. Copenhagen, WHO Regional Office for Europe, 2012 (Health Policy for Children and Adolescents, No. 6). Available from: http://www.euro.who.int/__data/assets/pdf_file/0003/163857/Social-determinants-of-health-and-well-being-among-young-people.pdf (accessed: 10 October 2019).
16. Ahluwalia N, Dalmasso P, Rasmussen M, et al. Trends in overweight prevalence among 11-, 13- and 15-year-olds in 25 countries in Europe, Canada and USA from 2002 to 2010. Eur J Public Health 2015; 25 (Suppl 2): 28-32.
17. Bibiloni Mdel M, Pons A, Tur JA. Prevalence of overweight and obesity in adolescents: a systematic review. ISRN Obes 2013; 2013: 392747.
18. Ogden CL, Carroll MD, Lawman HG, et al. Trends in obesity prevalence among children and adolescents in the United States, 1988-1994 through 2013-2014. JAMA 2016; 315 (21): 2292-2299.
19. Robertson W, Murphy M, Johnson R. Evidence base for the prevention and management of child obesity. Paediatr Child Health 2016; 26 (5): 212-218.
20. Salanve B, Peneuau S, Rolland-Cachera MF, et al. Stabilization of overweight prevalence in French children between 2000 and 2007. Int J Pediatr Obes 2009; 4 (2): 66-72.
21. Waters E, de Silva-Sanigorski A, Hall BJ, et al. Interventions for preventing obesity in children. Cochrane Database Syst Rev 2011; 7 (12): CD001871.
22. Wyatt KM, Lloyd JJ, Abraham C, et al. The Healthy Lifestyles Programme (HeLP), a novel school-based intervention to prevent obesity in school children: study protocol for a randomised controlled trial. Trials 2013; 14 (1): 95.
23. Vinck J, Brohet C, Roillet M, et al. Downward trends in the prevalence of childhood overweight in two pilot towns taking part in the VIASANO community-based programme in Belgium: data from a national school health monitoring system. Pediatr Obes 2016; 11 (1): 61-67.
24. Godin K, Leatherdale ST, Elton-Marshall T. A systematic review of the effectiveness of school-based obesity prevention programmes for First Nations, Inuit and Métis youth in Canada. Clin Obes 2015; 5 (3): 103-115.
25. Yoo BK, Hasebe T, Kim M, et al. Pilot survey of a novel incentive to promote healthy behavior among school children and their parents. Prev Med Rep 2017; 6: 286-293.
26. Eating healthy, growing healthy. Poland. December 2014. Available from: http://ecosysteme.danone.com/projectslists/eating-healthy-growing-healthy/ (accessed: 10 October 2019).
27. National program for the prevention of overweight and obesity and chronic noninfectious diseases through improved nutrition and physical activity for 2007-2011. Polish Ministry of Health, 2007. Available from: https://extranet.who.int/nutrition/gina/en/node/8142 (accessed: 10 October 2019).
28. World Health Organization. Regional Office for Europe. Nutrition, physical activity and the prevention of obesity : policy developments in the WHO European Region. WHO Regional Office for Europe, Copenhagen 2007. Available from: https://apps.who.int/iris/handle/10665/107843 (accessed: 10 October 2019).
29. Gajewska D, Harton A, Lange E, et al. Raport z projektu badawczo-edukacyjnego „Mądre żywienie – zdrowe pokolenie” realizowanego przez Polskie Towarzystwo Dietetyki w ramach dotacji przyznanej przez The Coca-Cola Foundation. [Report from the research project educational „Wise nutrition – healthy generation” implemented by the Polish Society of Dietetics under subsidy awarded by The Coca-Cola Foundation]. Dietetyka 2014; 8.

AUTHORS’ CONTRIBUTIONS
AH and JMR wrote the article. AH, JMR, DG, LW prepared the research concept and design, collected data and finally approved it. AH and DG revised the article.