Childhood obesity is a public health concern in Canada. Few published anthropometric data are available to indicate obesity prevalence in Canadian children. Obesity prevalence is reported for school-aged children in 11 London, Ontario, schools.
Data on body weight and height were obtained using standardized procedures. United States Centers for Disease Control and Prevention (CDC) body mass index (BMI)-for-age references and Cole's international BMI reference were used to classify the children's weight categories.
The study included 1,570 pupils aged six to 13. The CDC BMI references categorized 16.6% and 11.8% of children as overweight and obese, respectively. In comparison, when the Cole BMI reference and cut-off points were used, 17.5% and 7.6% of children were classified as overweight and obese, respectively.
Overweight is prevalent in the study population. Public health interventions are warranted to curb the obesity epidemic in school-aged children.
Purpose: Childhood obesity is a public health concern in Canada. Few published anthropometric data are available to indicate obesity prevalence in Canadian children. Obesity prevalence is reported for school-aged children in 11 London, Ontario, schools.
Methods: Data on body weight and height were obtained using standardized procedures. United States Centers for Disease Control and Prevention (CDC) body mass index (BMI)-for-age references and Cole's international BMI reference were used to classify the children's weight categories.
Results: The study included 1,570 pupils aged six to 13. The CDC BMI references categorized 16.6% and 11.8% of children as overweight and obese, respectively. In comparison, when the Cole BMI reference and cut-off points were used, 17.5% and 7.6% of children were classified as overweight and obese, respectively.
Conclusion: Overweight is prevalent in the study population. Public health interventions are warranted to curb the obesity epidemic in school-aged children.
Overweight and obesity have become major public health problems among children in countries around the world, including Canada (1). Like adult obesity, pediatrie obesity increases health risks. In children, these risks include childhood type 2 diabetes, hyperlipidemia, and hypertension (2-4). Furthermore, obese children tend to become obese adults (5). Because of the subsequent health consequences and a heavy health-care burden, primary prevention must target children (6). Measuring obesity prevalence rates is a prerequisite for planning and evaluating evidence-based public health intervention and prevention programs.
The prevalence of childhood obesity hinges on its definition and criteria. Defining overweight and obesity in children is complicated by normal growth processes, pubertal development, and body composition changes. The term "overweight" refers to excess weight in relation to height, while "obesity" refers to excessive body fat or adipose tissue in relation to lean body mass. Measuring body fat accurately is difficult. The ideal definition of obesity, based on percentage of body fat, is impracticable for epidemiological and clinical use (7). Although the word "overweight" may connote a milder degree of excess fat than does "obesity," no global consensus criteria exist to make this distinction. The terms are generally used interchangeably in the literature (8).
Body mass index (BMI) has been adopted as a simple measure of childhood obesity since the 1990s. Body mass index is a convenient way of measuring overweight and obesity in general practice. Because obesity is an excess of body fat, the ideal indicator in populations should be reliable and valid in reflecting body fat content (9,10). The rationale for using BMI as a measure of overweight and obesity in children is based on two factors. First, the high reliability of measuring height and weight makes BMI practical in the clinical setting or in population-based surveys (9,10). Second, BMI is a valid index of fatness. BMI is significantly correlated with laboratory measures of fatness in children and adolescents (11,12). Compared with the weight-for-height index, the advantage of BMI-for-age references as a measure of overweight in children is that age is taken into account. This is crucial because a child's body build and body composition change with age (13). The major limitation of BMI is its inability to distinguish increased fat mass from lean mass (14).
Several countries, including the United States, the United Kingdom, Germany, Italy, Australia, and New Zealand, have developed gender-specific BMI-for-age standards for children (10,15-20). Although Health Canada has established its own standards for adult obesity (21), it has not yet done so for children. Currently, different researchers are using two sets of BMI criteria in Canada (1,22-24).
Cole et al. developed the first set of BMI references (20). The Cole BMI references used data from six countries, including Brazil, the United Kingdom, Hong Kong, the Netherlands, Singapore, and the United States (20). Cole et al. drew centile curves that at age 18 years passed through the widely used cut-off points of 25 and 30 kg/m^sup 2^ for adult overweight and obesity (20). Children with a BMI of 25 or 30 at the extrapolated age of 18 were classified as overweight or obese, respectively (20).
The Centers for Disease Control and Prevention (CDC) developed the second set of BMI reference data, using five national health examination surveys from 1963 to 1994 and five supplementary data sources in the United States (10). The CDC gender- and age-specific BMI references define overweight in children as a BMI above the 95th percentile for age. Children between the 85th and 95th percentiles are considered at risk of being overweight (10). Recently, the CDC BMI reference and cut-off points were endorsed by Dietitians of Canada, the Canadian Paediatric Society, The College of Family Physicians of Canada, and the Community Health Nurses Association of Canada Nutrition Committee (25,26). This Canadian Collaborative Statement recommends the CDC BMI reference data and cut-off points for Canadian children, but labels weight categories differently from the CDC terms; a BMI between the 85th and 95th percentiles indicates that a child is "overweight," and a BMI above the 95th percentile indicates that a child is "obese" (25). The inconsistency in terminology, BMI reference data, and cut-off points leads to difficulties in comparing obesity prevalence rates among Canadian children with data cited in the literature.
Valid published BMI data sources are also needed to determine local and national childhood obesity prevalence. Although increasing national and local concern exists over the rising prevalence of childhood obesity, only a few measured BMI data have been available for Canadian children since the 1970s (1,22,23,27). In the majority of national surveys, children's BMI data were obtained from parents' or children's self-reported body weights and heights (24,28), which are unlikely to be as accurate as measurements. However, the recent Canadian Community Health Survey Cycle 2.2 on Nutrition does include actual measurements (1).
The current study was designed to collect BMI data based on measured body weight and height, and to report the prevalence of overweight and obesity among school-aged children. The study was conducted between 2001 and 2003 in 11 London, Ontario, elementary schools. In order that current results might be compared with data cited in the literature, both Cole et al. and CDC BMI references were used to classify overweight and obesity in this study population.
METHODS
The study was approved by the Research Ethics Board on the Use of Human Subjects at Brescia University College. Permission was obtained from local school boards before contact was initiated with individual schools.
Study subjects and sample selection
Children in grades 1 to 6 were studied. A convenience sample was used from 11 elementary schools, which were located in diverse socioeconomic areas in the City of London and County of Middlesex school districts. Postal codes were used as a proxy to identify socioeconomic status (SES) of the area in which the school is located. The Statistics Canada Postal Code Conversion File was used to convert the postal codes of targeted schools into Statistics Canada Census Tracts. "Incidence of low income" (ILI) on Census Tracts was used to define social classes of the areas (i.e., ILJ O to 6.2% = upper class area; ILI 6.29% to 16.6% = middle class area; ILJ 16.69% to 85% = low income area) (29). Four schools were in upper class areas, four were in middle class areas, and three were in low income areas. As school postal codes are a rough proxy for SES, no attempt was made to compare outcome measures among schools located in different SES areas.
All pupils in grades 1 to 6 in the targeted 11 schools were invited to participate. Parental consent was obtained before data collection, and only pupils with parental consent were eligible subjects.
Data collection
Children's weights and heights were measured by trained personnel using standardized procedures (30). Tanita medical scales (BWB-627A) were used to measure body weight to the nearest 0.1 kg. seca 214 "Road Rod" portable stadiometers were used to measure body heights to the nearest 0.1 cm. Each child was asked to remove her or his shoes and any excessive clothing before entering the measuring room. In order to respect privacy and promote a sense of comfort, each child was measured with no other children present. Weights and heights were measured twice and an average of the two values was calculated. Children's dates of birth were collected to calculate age.
Data analysis
Body mass index was calculated as weight (kg) divided by height (m) squared. Both CDC and Cole's BMI references were used to classify children's weight status.
CDC BMI reference: Epi Info 2000 software (CDC, Atlanta, GA, 2000) was used to calculate BMI percentile against CDC gender- and age-specific BMI references (10). The CDC-recommended BMI-for-age cut-off points (10), along with the Canadian labels (25), were used to define children's weight status; a BMI between the 85th and 95th percentiles defined a child as "overweight," while a BMI above the 95th percentile defined a child as "obese."
Cole's BMI references: The six-country "international" BMI dataset was used to classify children into die overweight and obese categories. Children with a BMI of 25 or 30 at the extrapolated age of 18 were defined as overweight or obese, respectively (20).
Data were analyzed using SPSS for Windows (ReI. 11.0, Chicago, IL, 2001). Overweight and obesity prevalence rates were described by gender. Kappa measure of agreement was performed to test the agreement of the overweight and obesity categories by the two BMI references.
RESULTS
Of the 3,368 pupils, 1,570 obtained parental consent and participated in the study. The response rate generated was therefore 47%.
Subjects' profile
Among the study pupils, 837 (53%) were boys and 733 (47%) were girls. In general, the sample was evenly distributed across age groups, with a range of 15-20% in each age interval, with the exception of the end spectrums, i.e., 12% at age six and 4% at age 12. Mean BMIs by age and gender are reported in Table 1.
Overweight prevalence
According to the CDC BMI references, 29% of boys and 28% of girls were overweight or obese. The Cole's BMI criteria classified 24% of boys and 26% of girls as overweight or obese (Figure 1).
Comparison of obesity prevalence rates
Figure 2 indicates that more children were classified as overweight by Cole than by CDC criteria. The kappa measure of agreement indicated, however, that the two classification systems are largely similar (kappa = 0.80, p<0 .001=".001" br="br"> DISCUSSION
The current results suggest that overweight and obesity are prevalent in this study population. About 25% of the children had body weights in unhealthy categories. Results from the current study strengthen the need for public health interventions to curb the obesity epidemic in school-aged children.
The inconsistent use of BMI criteria in classifying overweight and obesity in children makes comparing published obesity prevalence rates challenging. The current results, which were calculated using both Cole and CDC criteria, allow such direct comparisons of obesity prevalence rates within Canada and internationally. Tremblay et al. (24) reported that 33% of Canadian school-aged boys and 27% of girls were overweight, while 10% of boys and 9% of girls were obese according to Cole's BMI reference dataset and cut-off points. Tremblay's rates were higher than those reported in the current study, although the same criteria were used in both studies (24). This discrepancy may be due to the fact that the 1996 BMI data collected in the National Longitudinal Survey in Children and Youth were based on parent-reported body weights and heights, which may lead to over- or under-estimations (24).
In addition, Williams et al. (31) reported regional differences in overweight and obesity prevalence rates in Canadian children. The current dataset represents only a sample of children from London, Ontario, while Tremblay et al.'s data reflect the national figure; this may be another explanation for the inconsistency between our data and Tremblay et al.'s (24).
The most recently measured BMI data from the (Canadian Community Health Survey Cycle 2.2 on Nutrition Health showed that 18% and 8% of children between the ages of two and 17 were overweight and obese, respectively (1). As in our study. Cole's BMI reference dataset and cut-off points were used in the survey cycle. The survey cycle findings are very close to our results.
Similarly, overweight prevalence in the current study closely resembles that of American school-aged children in recent National Health and Nutrition Examination Surveys (NHANES) (Table 2) (32). The same measuring method and BMI cut-off points were used in the NHANES and the current study, although different terminologies were used.
Although the kappa measure of agreement indicated that the two BMI criteria have close agreement, the different cut-off points cause difficulty in the comparison of obesity prevalence rates in children. Because the use of the CDC BMI references in Canadian children has been endorsed by various Canadian health professional organizations (25), researchers would find the use of them beneficial in the reporting of overweight prevalence in Canadian children. Use of this BMI reference would facilitate direct comparison of overweight prevalence rates among Canadian children, as well as between Canadian and American children. Concurrent use ofCk)le's BMI references, the so-called "international BMI reference" (20), would allow comparison between Canadian and international data (25).
LIMITATIONS
The current study has a number of limitations. First, subjects were from a convenience sample of children from 11 of 130 elementary schools in the study areas. second, even though efforts were made to include schools located in different socioeconomic areas, response rates varied among schools. We are uncertain if SES differences existed between responders and nonresponders. These two pitfalls may have induced bias and may limit the generalization of results to the school-aged population in the City of London and the County of Middlesex. Third, the limited number of subjects in each age interval does not allow statistical comparisons of overweight prevalence across age groups. Last, but not least, individual families' SES information was not obtained, and so a comparison of overweight and obesity prevalence rates across SES classes is impossible.
RELEVANCE TO PRACTICE
Overweight and obesity are prevalent in the study population. Public healdi interventions are warranted to curb the obesity epidemic in school-aged children. Use of bodi the CDC and Cole's BMI references and cutoff points when reporting overweight and obesity prevalence would allow comparison between Canadian and international data.
Acknowledgements
The study was funded by the PHRED Program at Middlesex-London Health Unit Brescia University College provided salary support for work-study students responsible for data entry and verification. The authors acknowledge the Thames Valley District School Board and the London District Catholic School Board for allowing access to pupils in their elementary schools. The authors are grateful to the Middlesex-London Healdi Unit Child Health Team and to Brescia University College nutrition students for assistance in data collection. This study would have been impossible without the support and involvement of school principals, teachers, and staff. Pupils' and parents' participation and time are very much appreciated.
References
1. Statistics Canada. Canadian Community Health Survey: obesity among children and adults. Ottawa: Statistics Canada; 7Jun 2005.
2. Arslanian S. Type 2 diabetes in children: clinical aspects and risk factors. Horm Res 2002;57(Suppl l):19-28.
3. Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study. Pediatrics 1999;103:1175-82.
4. Young TK, Dean HJ, Flett B, Wood-Steiman P. Childhood obesity in a population at high risk for type 2 diabetes. J Pediatr 2000:136:365^9.
5. Serdula MK, !very D, Coates RJ, Freedman DS, Williamson DF, Byers T. Do obese children become obese adults? A review of the literature. PrevMed 1993:22:167-77.
6. Birmingham CL, Muller JL, Palepu A, Spinelli JJ, Anis AH. The cost of obesity in Canada. CMAJ 1999;160(4):483-8.
7. Pi-Sunyer FX. Obesity: criteria and classification. Proc Nutr Soc 2000;59(4):505-9.
8. Barlow SE, Dietz WH. Obesity evaluation and treatment: Expert Committee recommendations. The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services. Pediatrics 1998;102:E29.
9. Dietz WH, Bellizzi MC. Introduction: the use of body mass index to assess obesity in children. AmJ din Nutr 1999;70:123S-5S.
10. Kuczmarski RJ, Ogden CL, GrummerStrawn LM, et al. CDC growth charts: United States. Adv Data 2000;314:1-27.
11. Pietrobelli A, Faith MS, Allison DB, Gallagher D, ChiumeUo G, Heymsfield SB. Body mass index as a measure of adiposity among children and adolescents: a validation study. J Pediatr 1998; 132:204-10.
12. Lazarus R, Baur L, Webb K, Blyth F. Body mass index in screening for adiposity in children and adolescents: systematic evaluation using receiver operating characteristic curves. AmJ Clin Nutr 1996;63:500-6.
13. Must A, Dallai GE, Dietz WH. Reference data for obesity: 85th and 95th percentiles of body mass index (wt/ht2) and triceps skinfold thickness. Am J Clin Nutr 1991;53:839-46.
14. US Preventive Services Task Force. Screening and interventions for overweight in children and adolescents. Available at: http://www.ahrq.gov/clinic/uspstf/uspsobch.htm. Accessed 15JuI 2005.
15. Williams S. Body mass index reference curves derived from a New Zealand birth cohort. N Z MedJ 2000; 113:308-11.
16. Schaefer F, Georgi M, Wuhl E, Scharer K. Body mass index and percentage fat mass in healthy German schoolchildren and adolescents. Int J Obes Relat Metab Disord 1998;22:461-9.
17. Lynch J, Wang XL, Wilcken DE. Body mass index in Australian children: recent changes and relevance of ethnicity. Arch Dis Child 2000;82:16-20.
18. Luciano A, Bressan F, Zoppi G. Body mass index reference curves for children aged 3-19 years from Verona, Italy. Eur J Clin Nutr 1997;51:6-10.
19. Lindgren G, Strandell A, Cole T, Healy M, Tanner J. Swedish population reference standards for height, weight and body mass index attained at 6 to 16 years (girls) or 19 years (boys). Acta Paediatr 1995;84:1019-28.
20. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000;320:1240-3.
21. Health Canada. Canadian guidelines for body weight classification in adults. 2003. Ottawa: Health Canada; 2003.
22. Canning PM, Courage ML, Frizzell LM. Prevalence of overweight and obesity in a provincial population of Canadian preschool children. CMAJ 2004;171 (3):240-2.
23. He M, Sutton J. Using routine growth monitoring data for the tracking of obesity prevalence in young children. Can J Public Health 2004;95(6):419-23.
24. Tremblay MS, Katzmarzyk PT, Willms JD. Temporal trends in overweight and obesity in Canada, 1981-1996. Int J Obes Relat Metab Disord 2002:26(4):53843.
25. Dietitians of Canada, Canadian Paediatric Society, The College of Family Physicians of Canada, Community Health Nurses Association of Canada. The use of growth charts for assessing and monitoring growth in Canadian imams and children. CanJ Diet Prac Res 2004;65(l):22-32.
26. Rourke LL, Leduc DG, Rourke JT. Rourke Baby Record 2000. Collaboration in action. Can Fam Physician 2001;47:333-4.
27. Demirjian A. Anthropometry report-height, weight and body dimensions: a report from Nutrition Canada. Ottawa: Health and Welfare Canada; 1980.
28. Statistics Canada. National Longitudinal Survey of Children and Youth: childhood obesity. Ottawa: Statistics Canada; 18 Oct 2002.
29. Statistics Canada. Census 2001. Ottawa: Statistics Canada; 2004.
30. Cameron N. The measurement of human growth. London, UK Groom Helm; 1984.
31. Williams JD, Tremblay MS, Katzmarzyk PT. Geographic and demographic variation in the prevalence of overweight Canadian children. Obes Res 2003;11(5):668-73.
32. Hedley AA, Ogden CL, Johnson CL, Carroll MD, Curtin LR, Flegal KM. Prevalence of overweight and obesity among US children, adolescents, and adults, 1999-2002. JAMA 2004;291(23):2847-50.
Keywords Search:
Obesity; Public health; Nutrition; Diet; Elementary school students ; Body Mass Index, Child, Female, Health Surveys, Humans, Male, Nutrition Surveys, Ontario -- epidemiology, Prevalence, United States -- epidemiology, Child Nutrition Disorders -- epidemiology (major), Obesity -- epidemiology (major), Public Health (major)
The current results suggest that overweight and obesity are prevalent in this study population. About 25% of the children had body weights in unhealthy categories. Results from the current study strengthen the need for public health interventions to curb the obesity epidemic in school-aged children.
The inconsistent use of BMI criteria in classifying overweight and obesity in children makes comparing published obesity prevalence rates challenging. The current results, which were calculated using both Cole and CDC criteria, allow such direct comparisons of obesity prevalence rates within Canada and internationally. Tremblay et al. (24) reported that 33% of Canadian school-aged boys and 27% of girls were overweight, while 10% of boys and 9% of girls were obese according to Cole's BMI reference dataset and cut-off points. Tremblay's rates were higher than those reported in the current study, although the same criteria were used in both studies (24). This discrepancy may be due to the fact that the 1996 BMI data collected in the National Longitudinal Survey in Children and Youth were based on parent-reported body weights and heights, which may lead to over- or under-estimations (24).
In addition, Williams et al. (31) reported regional differences in overweight and obesity prevalence rates in Canadian children. The current dataset represents only a sample of children from London, Ontario, while Tremblay et al.'s data reflect the national figure; this may be another explanation for the inconsistency between our data and Tremblay et al.'s (24).
The most recently measured BMI data from the (Canadian Community Health Survey Cycle 2.2 on Nutrition Health showed that 18% and 8% of children between the ages of two and 17 were overweight and obese, respectively (1). As in our study. Cole's BMI reference dataset and cut-off points were used in the survey cycle. The survey cycle findings are very close to our results.
Similarly, overweight prevalence in the current study closely resembles that of American school-aged children in recent National Health and Nutrition Examination Surveys (NHANES) (Table 2) (32). The same measuring method and BMI cut-off points were used in the NHANES and the current study, although different terminologies were used.
Although the kappa measure of agreement indicated that the two BMI criteria have close agreement, the different cut-off points cause difficulty in the comparison of obesity prevalence rates in children. Because the use of the CDC BMI references in Canadian children has been endorsed by various Canadian health professional organizations (25), researchers would find the use of them beneficial in the reporting of overweight prevalence in Canadian children. Use of this BMI reference would facilitate direct comparison of overweight prevalence rates among Canadian children, as well as between Canadian and American children. Concurrent use ofCk)le's BMI references, the so-called "international BMI reference" (20), would allow comparison between Canadian and international data (25).
LIMITATIONS
The current study has a number of limitations. First, subjects were from a convenience sample of children from 11 of 130 elementary schools in the study areas. second, even though efforts were made to include schools located in different socioeconomic areas, response rates varied among schools. We are uncertain if SES differences existed between responders and nonresponders. These two pitfalls may have induced bias and may limit the generalization of results to the school-aged population in the City of London and the County of Middlesex. Third, the limited number of subjects in each age interval does not allow statistical comparisons of overweight prevalence across age groups. Last, but not least, individual families' SES information was not obtained, and so a comparison of overweight and obesity prevalence rates across SES classes is impossible.
RELEVANCE TO PRACTICE
Overweight and obesity are prevalent in the study population. Public healdi interventions are warranted to curb the obesity epidemic in school-aged children. Use of bodi the CDC and Cole's BMI references and cutoff points when reporting overweight and obesity prevalence would allow comparison between Canadian and international data.
Acknowledgements
The study was funded by the PHRED Program at Middlesex-London Health Unit Brescia University College provided salary support for work-study students responsible for data entry and verification. The authors acknowledge the Thames Valley District School Board and the London District Catholic School Board for allowing access to pupils in their elementary schools. The authors are grateful to the Middlesex-London Healdi Unit Child Health Team and to Brescia University College nutrition students for assistance in data collection. This study would have been impossible without the support and involvement of school principals, teachers, and staff. Pupils' and parents' participation and time are very much appreciated.
References
1. Statistics Canada. Canadian Community Health Survey: obesity among children and adults. Ottawa: Statistics Canada; 7Jun 2005.
2. Arslanian S. Type 2 diabetes in children: clinical aspects and risk factors. Horm Res 2002;57(Suppl l):19-28.
3. Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study. Pediatrics 1999;103:1175-82.
4. Young TK, Dean HJ, Flett B, Wood-Steiman P. Childhood obesity in a population at high risk for type 2 diabetes. J Pediatr 2000:136:365^9.
5. Serdula MK, !very D, Coates RJ, Freedman DS, Williamson DF, Byers T. Do obese children become obese adults? A review of the literature. PrevMed 1993:22:167-77.
6. Birmingham CL, Muller JL, Palepu A, Spinelli JJ, Anis AH. The cost of obesity in Canada. CMAJ 1999;160(4):483-8.
7. Pi-Sunyer FX. Obesity: criteria and classification. Proc Nutr Soc 2000;59(4):505-9.
8. Barlow SE, Dietz WH. Obesity evaluation and treatment: Expert Committee recommendations. The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services. Pediatrics 1998;102:E29.
9. Dietz WH, Bellizzi MC. Introduction: the use of body mass index to assess obesity in children. AmJ din Nutr 1999;70:123S-5S.
10. Kuczmarski RJ, Ogden CL, GrummerStrawn LM, et al. CDC growth charts: United States. Adv Data 2000;314:1-27.
11. Pietrobelli A, Faith MS, Allison DB, Gallagher D, ChiumeUo G, Heymsfield SB. Body mass index as a measure of adiposity among children and adolescents: a validation study. J Pediatr 1998; 132:204-10.
12. Lazarus R, Baur L, Webb K, Blyth F. Body mass index in screening for adiposity in children and adolescents: systematic evaluation using receiver operating characteristic curves. AmJ Clin Nutr 1996;63:500-6.
13. Must A, Dallai GE, Dietz WH. Reference data for obesity: 85th and 95th percentiles of body mass index (wt/ht2) and triceps skinfold thickness. Am J Clin Nutr 1991;53:839-46.
14. US Preventive Services Task Force. Screening and interventions for overweight in children and adolescents. Available at: http://www.ahrq.gov/clinic/uspstf/uspsobch.htm. Accessed 15JuI 2005.
15. Williams S. Body mass index reference curves derived from a New Zealand birth cohort. N Z MedJ 2000; 113:308-11.
16. Schaefer F, Georgi M, Wuhl E, Scharer K. Body mass index and percentage fat mass in healthy German schoolchildren and adolescents. Int J Obes Relat Metab Disord 1998;22:461-9.
17. Lynch J, Wang XL, Wilcken DE. Body mass index in Australian children: recent changes and relevance of ethnicity. Arch Dis Child 2000;82:16-20.
18. Luciano A, Bressan F, Zoppi G. Body mass index reference curves for children aged 3-19 years from Verona, Italy. Eur J Clin Nutr 1997;51:6-10.
19. Lindgren G, Strandell A, Cole T, Healy M, Tanner J. Swedish population reference standards for height, weight and body mass index attained at 6 to 16 years (girls) or 19 years (boys). Acta Paediatr 1995;84:1019-28.
20. Cole TJ, Bellizzi MC, Flegal KM, Dietz WH. Establishing a standard definition for child overweight and obesity worldwide: international survey. BMJ 2000;320:1240-3.
21. Health Canada. Canadian guidelines for body weight classification in adults. 2003. Ottawa: Health Canada; 2003.
22. Canning PM, Courage ML, Frizzell LM. Prevalence of overweight and obesity in a provincial population of Canadian preschool children. CMAJ 2004;171 (3):240-2.
23. He M, Sutton J. Using routine growth monitoring data for the tracking of obesity prevalence in young children. Can J Public Health 2004;95(6):419-23.
24. Tremblay MS, Katzmarzyk PT, Willms JD. Temporal trends in overweight and obesity in Canada, 1981-1996. Int J Obes Relat Metab Disord 2002:26(4):53843.
25. Dietitians of Canada, Canadian Paediatric Society, The College of Family Physicians of Canada, Community Health Nurses Association of Canada. The use of growth charts for assessing and monitoring growth in Canadian imams and children. CanJ Diet Prac Res 2004;65(l):22-32.
26. Rourke LL, Leduc DG, Rourke JT. Rourke Baby Record 2000. Collaboration in action. Can Fam Physician 2001;47:333-4.
27. Demirjian A. Anthropometry report-height, weight and body dimensions: a report from Nutrition Canada. Ottawa: Health and Welfare Canada; 1980.
28. Statistics Canada. National Longitudinal Survey of Children and Youth: childhood obesity. Ottawa: Statistics Canada; 18 Oct 2002.
29. Statistics Canada. Census 2001. Ottawa: Statistics Canada; 2004.
30. Cameron N. The measurement of human growth. London, UK Groom Helm; 1984.
31. Williams JD, Tremblay MS, Katzmarzyk PT. Geographic and demographic variation in the prevalence of overweight Canadian children. Obes Res 2003;11(5):668-73.
32. Hedley AA, Ogden CL, Johnson CL, Carroll MD, Curtin LR, Flegal KM. Prevalence of overweight and obesity among US children, adolescents, and adults, 1999-2002. JAMA 2004;291(23):2847-50.
Keywords Search:
Obesity; Public health; Nutrition; Diet; Elementary school students ; Body Mass Index, Child, Female, Health Surveys, Humans, Male, Nutrition Surveys, Ontario -- epidemiology, Prevalence, United States -- epidemiology, Child Nutrition Disorders -- epidemiology (major), Obesity -- epidemiology (major), Public Health (major)
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