I wish I had my copy of GCBC with me. I'm relying on Google books for this quote which is on p. 300 of GCBC.

"Just as we will decrease energy expenditure in response to caloric deprivation, we will also increase expenditure in response to caloric surplus. ... It has since been encapsulated in a German word, Luxuskonsumption, which means a spendthrift metabolism that wastes excess calories as heat or superfluous physical activity."