Let's chew the fat (late 19thC.) a bit, chewing having long been associated with talking — the same muscular movements required for mastication and conversation. Just don't talk and chew at the same time. Little consensus exists as to the origins of the fat. Some point to grousing of 19th century sailors engaged in conversation while sinking their teeth into the standard ration of tough and rancid pork. Grousing, indeed, considering all that murmuring and grumbling simply imitating the Greek gru, for a "grunt."
Others emphasize instead how little sustenance you get from fat and how that measures up nicely with the substance of most conversations. That was, of course, well before we learned the difference between trans-fat that kills and the "good fat" found in nuts, etc.
In a more nutritional vein, Mom always stressed taking small bites and chewing our food thoroughly. We responded by reducing the size of the information we have to swallow. Candidates for public office did their part by shortening discourse into sound bites. Each year, sound bites get smaller and smaller. The average bite was 42.3 seconds in the '70s, 9.8 seconds in the '80s, and 5 seconds or less today.
Cattle don't buy that philosophy, however, swallowing grass whole into a special stomach and bringing it back later for leisurely mastication. This process is called rumination, from the Latin, rumen, "throat," or "gullet" and ruminari, "to chew the cud." Ruminate — then chew on that a bit.