Body mass index (BMI) and waist circumference are commonly used tools to identify potential health risks. Figure 19 provides information based on different data sources but both rely on a survey question that asks participants to state their height and weight to estimate the BMI of respondents. It has been demonstrated that individuals tend to underestimate their body weight and overestimate their height resulting in underreporting of the number of individuals who are overweight, obese or morbidly obese.
Figure 19 shows that a significant proportion of the population is overweight, obese or morbidly obese. The First Nations Regional Longitudinal Health Survey (RHS) provides the results for First Nations men and women, and indicates that approximately three adults in four are overweight, obese or morbidly obese. For Albertans and Canadians, almost one in two adults is overweight, obese or morbidly obese.
An Alberta study20 looked more closely at each BMI group and how the prevalence of chronic diseases was reported. While the information is not provided for First Nations, it does provide information on trends and likely occurrences. Figure 20 maps the proportion of individuals within each group who report chronic diseases and shows that the BMI range with the highest proportion of individuals without chronic diseases are those in the normal range (18.5 to 24.9). For the individuals in the morbidly obese BMI range (over 40), the revelance of chronic diseases is significantly different, as only 12 per cent of them are not reporting a chronic disease other than obesity.
Figure 21 provides the BMI for First Nations children and youth in Canada living on-reserve. It shows that children (0 to 11 years of age) are much more likely to be overweight or obese than First Nations youth (12 to 17 years of age). The next edition of the RHS should indicate whether this is a new trend and if obesity rates are increasing among younger First Nations. The RHS did not find any significant differences in BMI rates for First Nations children, however, they did identify gender differences with youth as 62.3 per cent of teenage girls had an underweight and/or normal BMI compared to 54.5 per cent of teenage boys. A higher proportion of First Nations children and youth had a healthy weight in comparison with the adult population.
20Self-Reported Body Mass Index and its correlates in Alberta: A portrait from survey and administrative data sources, Health Surveillance, Alberta Health & Wellness, April 2005