White bread : The White bread is a pain made of wheat flour from which the consist of and germs which gives it this very white color.
Eat your white bread (in / the first): go from one happy state to one that is not.
This expression is attested in at a time when for the people, the bread was not made with white flour, not free of its impurities as is the case today. But when one had access to a finer and whiter flour, that generally reserved for the high society, the people did not hesitate to make bread more than usual, of the "white bread" of the quality and. with superior taste. Suddenly people then tended to eat it first, an understandable weakness, condemning themselves to sharing the worse bread later.
The use of this old metaphor has become generalized on all occasions when one started by doing pleasant things ("eating white bread") first without always knowing that one would then have to suffer the various inconveniences (eating the white bread). black bread, which has also been called the “black bread of adversity”).