= remove what is not needed = eliminate the nonessential The company trimmed the fat by cutting 1000 jobs.

As background, the phrase has a literal meaning. Muscles are surrounded by fat, and trimming the fat from a piece of meat means to remove it skillfully. When I was a kid butchers did not customarily trim fat from meat unless asked. My mother always looked steaks and roasts with a layer of fat still on them. They was served on the plate with a centimeter of fat surrounding them. Some people ate the fat, some cut it off.

I usually see it used as a slang term in business and finance that means to remove excesses that are not needed or no longer needed. For example, there is an article on the internet called "9 Ways to Trim the Fat From Your Spending" and what they mean is to cut excess spending on things you don't really need to you can reallocate that money to something more valuable. Another article was "Trim the Fat From Your Startup" which means eliminating waste or poorly used resources and focusing those resources where they will improve the business most. Sometimes you hear trimming the fat in conjunction with cutting jobs and firing people from their jobs...as those jobs are seen as not valuable and so are cut to run more lean (so to speak).