The Jevons Paradox

It seems like a good idea at first glance.  Low-fat cookies.  So you buy them.  But because they low-fat, you eat more of them than you would have if they were high-fat.  So your total fat intake actually ends up being more.

This is the Jevons Paradox.

http://www.newyorker.com/reporting/2010/12/20/101220fa_fact_owen

Jevons frames the concept, though, in terms of energy efficiency.  If you are running low on a resource, it seems to make sense to be more efficient in its use.  However, that increased efficiency leads to a net increase in use:

The problem with efficiency gains is that we inevitably reinvest them in additional consumption.

Of course, it's not bad to increase efficiency. It often leads to reduced costs or greater output. But it won't lead to reduced consumption.