A study funded by the Canadian Fitness and Lifestyle Research Institute and conducted by Susan Crawford and colleagues from the University of British Columbia found clear evidence that obesity has increased among Canadian children between the ages of 7 and 12. Between 1981 and 1988, childhood obesity increased by over 50%, as evidenced by measurements of subcutaneous fat taken with skinfold calipers.

The 1981 Canada Fitness Survey and the 1988 Campbell Survey on Well-Being in Canada (which still provide the most recent national data on children's obesity) show the rate of obesity increasing from a baseline level of 15% in 1981 to 24% in 1988. The increase for boys went from 15% to about 20% — less than the increase for girls, which went from 15% to about 26%.

To slow the rise in obesity among children, we need to address behaviours such as physical activity. These behaviours are established in childhood and tend to persist into adulthood.

Ideally, children should be active enough to prepare them for a lifetime of physical activity and to enhance their physical and psychological health. Recent physical activity guidelines for children and adolescents suggest that an optimal goal is 6 to 8 KKD (kilocalories/kilogram of body weight/day). For the purposes of the 1995 Physical Activity Monitor, conducted by the Institute, the possible tendency of parents to overestimate their children's participation in physical activity was offset by setting the guideline at 8 KKD.

The results show that over one-third of children aged 5 to 17 satisfy this guideline for optimal health and development. An additional one-fifth fall just short of the guideline. The remaining half either meet only the minimum standard equivalent to walking a total of one hour daily or are considered sedentary altogether.

Boys are clearly more likely than girls to meet the optimal guideline for physical activity, which reflects the greater increase in obesity observed among girls. The difference is more pronounced among teenagers, where almost twice as many boys as girls expend at least 8 KKD.

Nevertheless, meeting the optimal guideline for physical activity is a goal well within our children's reach. While only one-third of children meet the optimal energy expenditure of 8 KKD, the average energy expenditure is not far behind, at 7.3 KKD. A small increase in average daily energy expenditure would allow considerably more children to meet the guideline.

To help children become more active, parents, teachers and other adults involved in caring for children can

• provide physical and social environments that encourage regular and enjoyable participation in physical activity;
• provide the knowledge, attitudes, skills and confidence children need to adopt a physically active lifestyle.

Starting at a very young age, children will benefit from an environment conducive to frequent activities, whether structured or unstructured.