Does sprawl cause obesity?

I’m unconvinced by the argument that suburban sprawl is obesity’s best friend. I’m equally suspicious that higher density living is justified as a sensible response to obesity, as this story in the Sydney Morning Herald, How City Living Fights the Waistband Sprawl, contends.

It’s not that I doubt there’s a correlation between obesity and distance from the city centre. The SMH story reports University of NSW researchers as finding that “those living in the outer suburbs were 30 to 50 per cent more at risk of being overweight and 40 to 60 per cent less likely to be physically active than their inner-city counterparts”.

Nor do I doubt that the physical environment might have some role. After all, 13% of inner city residents in Melbourne walk to work compared to just 1% in the outer suburbs.

But how much of this difference is due to low density living? Is the relationship causal?

Even at first glance, weight gain seems to me to be much more sensitive to what you eat than what you do (or don’t do). For example, you have to walk the dog for an hour and a half, or cycle for an hour, to burn off the calories in just one Big Mac. Isn’t it likely that all those suburban families eat more fast food than inner city latte sippers?

So differences in diet are probably a much more significant factor explaining obesity than low density living. Read the rest of this entry »