The saying "living off the fat of the land" means to live well by taking advantage of the world's abundance and whatever the world has to offer. The expression implies living comfortably without too much hardship. Taking advantage of what the world has to offer can be understood in relation to any set of circumstances, ranging from an agrarian existence to the highest degree of modern affluence. Sometimes the idiom also implies opulence, excess or laziness, but these are secondary connotations.
Early definitions of the word "fat" refer to the best, richest or most rewarding part of something. In this sense, one of the earliest references to this phrase comes from the King James Bible, in Genesis 45:17-18. Here, Joseph is instructed to go to Canaan, where he will be given "the good of the land of Egypt." He is told that upon his arrival he will "eat the fat of the land." This passage suggests that the land will yield abundance for his family.
"Living off the fat of the land" has historically carried a sense of abundance yielded from the Earth itself, such as from plentiful crops grown in rich soil or from a cornucopia of naturally available resources. This phrase might refer to a lush natural environment that needs little cultivation to sustain human life — a place good for farming, fishing, hunting or anything else that is immediately life-sustaining. Modern interpretations might include reference to valuable things beneath the land, such as gems or fossil fuels. Other interpretations might extend the historical meaning to the realms of industry, commerce or economics.
When the expression is applied to a natural environment, it often denotes farming, anti-consumerism or a simple lifestyle. Such references might include the idea of a "return to nature" in which individuals might abandon the complexities of modern society to simply "live off the fat of the land." This meaning is almost the opposite of another modern connotation that equates the expression with affluence and excess.
In cases where the idiomatic expression "living off the fat of the land" refers to first-world affluence, the implication is that this bounty has come relatively easily to whomever has it. A negative value judgment is sometimes attached to this usage of easy prosperity, but not always. When the idiom references great wealth, there is often an implied complacency, false entitlement or sense of wealth taken for granted.