This study is to update the estimates of the economic burden of illness because of overweight and obesity in Canada by incorporating the increase in prevalence of overweight and obesity, findings of new related comorbidities and rise in the national healthcare expenditure. The burden was estimated from a societal perspective using the prevalence-based cost-of-illness methodology. Results from a literature review of the risks of 18 related comorbidities were combined with prevalence of overweight and obesity in Canada to estimate the extent to which each comorbidity is attributable to overweight and obesity. The direct costs were extracted from the National Health Expenditure Database and allocated to each comorbidity using weights principally from the Economic Burden of Illness in Canada. The study showed that the total direct costs attributable to overweight and obesity in Canada were $6.0 billion in 2006, with 66% attributable to obesity. This corresponds to 4.1% of the total health expenditures in Canada in 2006. The inclusion of newly identified comorbidities increased the direct cost estimates of obesity by 25%, while the rise in national healthcare expenditure accounted for a 19% increase. Policies to reduce being overweight and obese could potentially save the Canadian healthcare system millions of dollars.