A law of Economic theory. Income spent on food, as a percentage of overall income, decreases as income increases, other factors remaining constant. This law suggests that the percentage of income spent on food increases more slowly than the percentage increase in income. Contrast that to the idea that less money is spent on food as income increases. German statistician Ernst Engel (1821-96) proposed this law in his 1857 paper. This is a different person than Friedrich Engels, Karl Marx’s associate (see communism).