Are you gonna finish that?

If you don’t, somebody probably will, even if they don’t need it. Perhaps especially if they don’t need it.

As we’re deciding whether to dollop the mashed potatoes on the side or smear them directly onto the leftover turkey sandwich - whichever retains more gravy - consider that holiday feasts are only the highest peaks on a rising range of rich foods, much richer than human bodies are used to but which we take for granted.

As the everyday standard rises, holiday meals must become ever more elaborate to avoid mundanity. And we just eat it up, so to speak.

The Centers for Disease Control and Prevention announced that more than one-quarter of all adults in 30 of the 50 states are so severely overweight they’re considered obese. The “winners” in this competition are Mississippi and West Virginia, where two-thirds of all adults are overweight - but it was close. Kentucky is only a couple of percentage points behind both.

The body naturally craves sweets, fats and starches because our distant ancestors didn’t get too many of them. Our stomachs say, “Given a choice, go for the rich stuff! You may not get more anytime soon!”

But now we do. Our agricultural capacity has outstripped our normal stomach volume, an anomaly in human history. And so we get fat. Our bodies, unprepared for the influx, develop things like diabetes and heart disease.

Usually, humans have fought to get enough to eat, not to keep weight off. But even the feeling of being full can be deceptive, as writer P.J. O’Rourke found on a trip to the Soviet Union during its last days. He noticed how many refrigerator-sized Russians were stumping around, even as the farm economy sputtered. The reason? Lard and potatoes. That’s about all they got. Filling, but not very nutritious. That deficiency made them want more. As one woman he interviewed said, “The two biggest problems we have are losing weight and getting enough to eat.”

Very few countries have had too much to eat; those that did were usually at the top, economically or politically, and displayed their power through food.

According to Cecil Adams’ column “The Straight Dope,” debunking rumors and answering weird questions for more than three decades, it’s not really true that gluttonous Romans deliberately threw up so they could eat some more. But we do have an indication in contemporary fiction of how ostentatious they could get around the table.

The first-century Roman author Titus Petronius Arbiter - probably lampooning his boss, the Emperor Nero - described the incredible vulgarity and indulgence of the nouveau riche in a famous passage. “Trimalchio’s feast” makes for great after-dinner reading, describing how a freed slave showed off his sudden wealth to dinner guests - who were all just flattering him to cadge a free meal. Petronius told of pastry-covered eggs, a roast pig full of live birds, fake birds shaped from pork (ancient Spam?), fruit stuffed with saffron, dormice dipped in honey and other exotic or ridiculously elaborate courses. While the piece was obviously written for comedic effect, it had to be fairly close to reality in order to be funny.

In fact, fat has been rare enough throughout history to be seen as a mark of wealth, and sometimes beauty. Of course, some of those who saw it that way had serious problems of their own. Ibrahim the Mad, a 17th-century Turkish sultan, decided that the fattest woman in the Ottoman Empire would be the most beautiful too. His servants eventually found him a gigantic Armenian woman he dubbed “Sugar Cube,” whom he showered with gifts and honors. Eventually he made her governor-general of Damascus, a position not normally earned by eating.

On the Pacific island of Tonga, fat has traditionally been a mark of beauty. Of the island nation’s 100,000 or so residents, about 90,000 are overweight, enabled by a diet high in starchy vegetables and fatty pork. As a result, 20 percent of Tongan adults are diabetic, compared with 8 percent of Americans. But we’re catching up.

Sub-Saharan Africa is generally thought of as a place where people regularly starve, so you can imagine how distinctive a round body would be there. And that’s what traditionalists in Mauritania aim for. A generation ago, more than a third of young women in Mauritania were seriously overweight, according to the BBC. Now that’s down to one in 10, but causes serious health problems for them.

Again, “skinny” means “poor” to old-fashioned Mauritanian men, so young girls can be shipped off to special “fat farms” that are the opposite of such places in America. There girls are force-fed dates and couscous until they balloon past Mississippian proportions.

The result is an obvious statement of wealth and (momentary) health in an otherwise very poor country. As in Tonga, as in Rome, taking seconds and thirds is a way of showing off.

Who are we showing off for?

— Jim Gaines is a reporter for the Daily News. He can be reached at 783-3242 or by e-mailing jgaines@bgdailynews.

com.