When faced with abundance, the brain's ancient reward pathways are difficult to suppress. In that moment, the value of eating the chocolate cake exceeds the value of the diet. We cannot think down the road when we are faced with a chocolate cake.
Peter Whybrow - American Mania
Whybrow also says that this phenomenon is why people are in debt as well. The instant reward is hard for our brains to bypass...our brains were wired to accumulate for times of scarcity....take scarcity away and take a look around at what the result is.