Obesity—a growing issue ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○
Christel Le Petit and Jean-Marie Berthelot
This article, based on longitudinal data, follows a sample of people who were aged 20 to 56 in 1994/95 to determine the percentage who made the transition from normal to overweight, or from overweight to obese by 2002/03.
Characteristics that increased the chances of overweight people becoming obese are examined.
The data are from five cycles of the National Population
Health Survey, 1994/95 through 2002/03.
Cox proportional hazards modelling was used to identify variables associated with an increased or decreased risk of becoming obese; 1,937 men and 1,184 women who were overweight in 1994/95 were selected.
Close to a third (32%) of people who were aged 20 to 56 and of normal weight in 1994/95 had become overweight by
2002/03. During the same period, almost a quarter of those who had been overweight in 1994/95 had become obese.
Among people who were overweight, the risk of obesity was relatively high for younger men and members of lowincome households. Overweight men who smoked or who had activity restrictions had a high risk of obesity. Physical activity helped women avoid obesity.
body mass index, body weight, longitudinal studies, weight gain Authors
Christel Le Petit (613-951-3856; Christel.LePetit@ statcan.ca) is with the Health Analysis and Measurement
Group at Statistics Canada, Ottawa, Ontario, K1A 0T6.
Jean-Marie Berthelot, formerly at Statistics Canada, is with the Canadian Insitute for Health Information in Ottawa.
Health Reports, Vol. 17, No. 3, August 2006
besity is recognized as a major public health problem that rivals smoking as a cause of
illness and premature death. Obesity has been
linked with type 2 diabetes, cardiovascular disease, hypertension, stroke, gallbladder disease, some forms of cancer, osteoarthritis and psychosocial problems.1 The impact on life expectancy is considerable: among American non-smokers, obesity at age 40 has been associated with a loss of 7.1 years of life for women and 5.8 years for men.2
The same American study estimated that even being overweight reduced both male and female non-smokers’ life expectancy by more than three years.
Obesity results when people consume far more calories than they use (see Calculating overweight and obesity). This imbalance has been attributed to a variety of factors that characterize modern life: fast food, growing portion sizes, a sedentary lifestyle, and suburban designs that tend to discourage walking.3
Statistics Canada, Catalogue 82-003
Obesity—a growing issue
This analysis is based on longitudinal data from the first five cycles of the National Population Health Survey (NPHS), 1994/95 through
2002/03. Since 1994/95, the NPHS has collected information about the health of the Canadian population every two years. It covers household and institutional residents in all provinces and territories except members of the regular Armed Forces, people living on
Indian reserves or in some remote areas, and civilian residents of military bases. Although residents of health care institutions are part of the survey, they are excluded from this analysis.
In 1994/95, 20,095 individuals were selected for the longitudinal panel. Of these, 17,276 agreed to participate, for a response rate of 86.0%. The response rates for subsequent cycles, based on these 17,276 respondents, were: 92.8% in cycle 2 (1996/97);
88.2% in cycle 3 (1998/99); 84.8% in cycle 4 (2000/01); and
80.6% in cycle 5 (2002/03).
More detailed descriptions of the NPHS design, sample and interview procedures can be found in published reports.4,5
The proportion of people moving from one weight category to