Purpose: The objective of the paper is to describe trajectories of health-related quality of life (HRQL) associated with categories of body mass index (BMI): underweight, normal weight, overweight, obese class I, and obese classes II and III.
Methods: Data come from the longitudinal Canadian National Population Health Survey. Analyses are based on data for 3,864 men and 4,745 women who were 40+ in 1998/1999 and followed through 2006/2007. HRQL was measured with the Health Utilities Index Mark 3. Multi-level growth modeling was used.
Results: HRQL declined with age. For men, there was a large HRQL decrement for being underweight; trajectories for all other BMI categories were very similar. For women being underweight was associated with higher HRQL at younger ages but lower at older ages. Otherwise, for women, HRQL was ordered from highest to lowest: normal, overweight, obese class I, and obese classes II and III.
Conclusions: Given that excess weight is a risk factor for mortality and the development of chronic conditions, the HRQL results for men are surprising. The HRQL results for women may reflect both the importance of body image on mental health and the health effects of excess weight.