School Exercise Programs Have Many Benefits – Weight Loss is Not One of Them

Anyone still hoping that school-based exercise programs will prove to be the “silver bullet” against childhood obesity should probably read the latest meta-analysis on this topic, just out in this week’s issue of CMAJ.

In this carefully conducted analysis of the literature, Kevin Harris and colleagues from BC Children’s Hospital, Vancouver, BC, Canada, find no evidence to suggest that school-based physical activity interventions improve BMI, although they certainly have other beneficial health effects.

This finding is not unexpected – not only is exercise alone simply not the most efficient way to control weight, it is also not likely that an intervention that only addresses a small proportion of childrens’ total daytime activity will have any measurable impact on body weight.

This does not mean that increasing activity in school is bad – as pointed out before in these pages – there are numerous other benefits of being physically active.

It so happens that just yesterday, I had the pleasure of listening to Dr. Mark Tremblay, Professor of Pediatrics at the Children’s Hospital of Eastern Ontario and Chief Scientific Officer of Active Healthy Kids Canada, at the 4th University of Alberta Annual Nutrition Symposium, hosted by the Students of Nutrition 440.

As Tremblay pointed out: to affect body weight, the target should be to reduce sedentariness – which is not the same as increasing the amount of exercise. There is no reason to assume that a few extra minutes of physical activity at school can cancel out the many hours of screen time and the considerable time spent indoors, not to mention the deleterious effects of caloric-dense unhealthy diets.

Edmonton, Alberta

p.s. Thanks to all the students who hosted “Obesity: Why the Weight?” – I had a great time – thanks for inviting me.!