In the first study to compare self-reported and measured body mass index (BMI) in the Canadian population as a whole, McMaster University researchers show that the prevalence of obesity—based on measured BMI—is 3.0%. In comparison, self-reported estimates of BMI put the prevalence of obesity at 15.6%. This difference (7.4%) has major implications for public health, given the physical and psychological repercussions of obesity, as well as for research into the origins of disease. In this study, the research team, led by Noori Akhtar-Danesh from McMaster's Department of Nursing, also reports a new model based on age, sex, self-reported weight and self-reported height for predicting actual BMI.
Additional results: • Women are more likely than men to underestimate their BMI; • Individuals in the 31–50 age group under-report BMI; • Obese individuals are more likely to under-report BMI.
Data analyzed was from the Canadian Community Health Survey, Cycle 2.2, and included self-reported BMI for 7589 adults (aged 18 years and over) and measured BMI for 12 428.
Noori Akhtar-Danesh, PhD, is with the School of Nursing, McMaster University and the Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ont. Mahshid Dehghan, PhD, is with the Population Health Research Institute, McMaster University, Hamilton, Ont. Anwar T. Merchant, ScD is with the Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC. James A. Rainey, RN, BScN, is with the School of Nursing, McMaster University, Hamilton, Ont.