Weight and global warming

While searching for articles about fat taxes I came across this piece about fat and global warming:

Overweight people eat more than thin people and are more likely to travel by car, making excess body weight doubly bad for the environment, according to a study from the London School of Hygiene & Tropical Medicine.

They estimate 10% increased emissions from being overweight. Sadly I don’t have time to read the original articel right now, but at least the newspaper’s conclusion sounds shaky. For a start, do fat people eat any more than slim people of the same weight? Are the decisions to overeat and drive more both explained by unobserved cultural factors, rather then one explaining the other? The first would be easy to control for in a regression, the second less so.

Moreover, even if the newspaper quote is entirely accurate, the conclusion that we need to do something about fat people is erroneous. What we need to do is do something about the carbon emissions by forcing people to bear the social cost of them. Once that is done, any decisions to overeat internalise the cost to the planet, and are made efficiently. It is ridiculous to go around pointing at individual decisions that hurt the environment and trying to change them individually. Since they have a common factor — not pricing the emissions caused by the decision — that’s what we need to target, and then they’ll all sort themselves out!