I was chatting with a senior medic on the train a while ago, when he surprised me by saying that he believed there is consensus in medical opinion that the underlying cause of obesity is not eating more, or even eating junk, but indolence.

After a little googling around, I came up with a BBC quote from the Director of the UK Medical Research Council National Survey of Health and Development to essentially the same effect.  Couple that with the fact that just one in twenty now walk or cycle to school, as opposed to four in five c. 1970), and it’s no surprise that one in seven British children are now obese.

Car culture seems to see people walking as a threat, and cycling as an even bigger one.  It is not unusual to hear abuse from ‘motorists’ or even have things thrown at you through their window as they pass.  I have suffered both, and have even experienced people deliberately driving at me.  Bus drivers in Oxford follow dangerously close as a matter of course.

This is very strange.  I invite explanation.

Of course, within sprawl, you have little or no choice but to drive on every occasion.  Far from the necessary 3,000 steps a day for basic exercise, you will struggle to manage 300.  It’s a curious irony that workaholicism, or simply long working hours imposed upon you, will combine with a car-predicated habitat to deny you the ability to dedicate additional time specifically to exercise.  After sitting in congestion two or more hours a day, and working ten or more, there isn’t any time left.

And so we continue to put on weight, cumulatively.  Until our cardiovascular system says stop.

An interesting footnote is a suggestion that fatter drivers use more gas.  While this is amusing (along with the obvious jocular aside), the effect is small when one accounts for the enormous mass ratio of the typical American car.  In moving from simply overweight into obesity, we increase our mass by about 50%.  But this still represents only around 10% of the total mass, since cars have also gained mass in around the same proportion.  Even if this were not so, the increased bill at the pump would be down in the ‘noise’ — the statistical variation associated with our mileage and vehicle efficiency.

More significant perhaps is the tendency to both use a larger vehicle and to walk less, the fatter we become.  And so, we drive more, and further deter others from walking.

Which, of course, closes the positive feedback loop.