If the Academy of Nutrition and Dietetics is saying that Kraft Singles are good for us, surely schmaltz is next.

The metaphoric meaning of schmaltz is sentimentality – a heart-tugging moment, accompanied by real or virtual violins. The literal meaning of schmaltz is rendered poultry fat, a heart attack on a plate, the Jewish lard indispensable for making the crackly fried chicken skin treats called gribenes.

The metaphoric meaning of Kraft Singles is blandness – the absence of taste, texture or variety. (See also: Velveeta.) Its literal meaning is as American as American cheese: shiny, rubbery, yellow-orange, imperishable plastic-wrapped slices of processed “pasteurized prepared cheese product,” as it says on the label, perfect for a lunch box or apulled pork and red onion melt.

Kraft Singles is the first product on which the Academy of Nutrition and Dietetics has bestowed the privilege of putting its “Kids Eat Right” logo on the package. You might think such a logo is a nutritional seal of approval, just as you might think the academy is a reliable source of guidance for parents. But though Kraft does call it an endorsement, the academy denies it. Though the Academy represents 75,000 registered dietitians and other nutritional professionals, the New York Times calls it “a trade group” and notes that it “has been criticized by some of its members and by health advocates over what they say are its overly cozy ties to industry.” A founder of Dietitians for Professional Integrity, which the Times identifies as “an organization for disenchanted academy members,” says that when he heard the academy had awarded its first endorsement to Singles, “My jaw just hit the floor and my eyebrows just hit the ceiling.”

You can’t blame parents, or any of us, for being baffled by wellness advice.

In the 1980s, products labeled “fat free” flew off the shelves. But now we know that the high-fructose corn syrup, salt and chemicals in them made them worse than fat, and higher in calories and carbs, than the products they were simulating.

In the 1950s and 60s, wheat germ was considered a “health food.” Today it’s shunned for its gluten, and millions of people not suffering from celiac disease or Crohn’s disease have nevertheless made what the Wall Street Journal calls “the Gluten-Free Craze” the grocery business’s new cash cow.

“Butter Is Back,” New York Times op-ed columnist Mark Bittman wrote last year, citing an Annals of Internal Medicine review. I can’t believe I used to buy “I Can’t Believe It’s Not Butter! Light” by the tubful. What was I thinking?

It’s not just butter. “Eggs Are Back,” too. That headline in the Atlantic last month was prompted by the recommendations of the U.S. government’s 2015 Dietary Guidelines Advisory Committee. It turns out that dietary cholesterol and blood cholesterol aren’t as tight with each other as we once thought. Or maybe not.

Oh, and coffee – the high test, caffeinated brew – is back, too.

And so is salt.

On the other hand, the medical evidence – or rather, the lack of medical evidence – is stacking up that the vitamin and mineral supplements we take to compensate for deficiencies in our diet don’t do us any good. Herbal supplements may be worthless, too, or at a minimum bogus, according to the New York State attorney general’s office, which found that four out of five top-selling brands at GNC, Target, Walgreens and Walmart contained none of the herbs listed on their labels, though they probably provide a full day’s nutritional requirements for powdered rice and houseplants. As long as senator Orrin Hatch (R-Ut.) is standing guard, don’t expect this to change.

Exercise is also subject to pendulum swings. Stretching before working out used to be gospel; now we’re warned it can actually cause injury. Yoga is good; yoga can wreck your body. High-impact exercise is good for you (1980s); no, it’s bad for you (1990s); no, wait, it’s OK after all. But only in moderation. “A Danish study,” reports the Los Angeles Times, “recently concluded that high-intensity, high-mileage joggers die at the same rate as channel-surfing couch potatoes.”

And don’t get me started on sunbathing.

If you’ve seen Woody Allen’s 1973 film “Sleeper,” a story set 200 years in the future, you’ll remember the doctors discussing “the charmed substances” – like wheat germ, organic honey and tiger’s milk – “that some years ago were felt to contain life-preserving properties.”

Dr. Melik: You mean there was no deep fat? No steak or cream fries? Or hot fudge?

Dr. Agon: Those were thought to be unhealthy, precisely the opposite of what we now know to be true.

Dr. Melik: Incredible.

That moment is funnier, sadder and truer now than when the movie came out. Our wellness knowledge and ignorance are moving targets. As each new study seems to contradict the previously contradictory advice that we’ve barely re-rejected, skepticism toward all studies looks like a reasonable response. Unstable norms make it easier for Kraft to cut a mutual endorsement deal with the Academy of Nutrition and Dietetics. It makes it likely that when Carl’s Jr. introduces a new Mile High Bacon Thickburger, weighing in at half a day’s recommendedcalories, and a full day’s salt and fat, hardly a jaw drops or an eyebrow hits the ceiling. When accepted wisdom about healthful living keeps getting turned on its head, the odds of beating epidemics like obesityand diabetes get longer.

A recent study in Science by two professors at Johns Hopkins School of Medicine reports that bad luck – not bad health habits, not heredity or environmental factors, but random mutations – may account for two-thirds of the risk of getting many types of cancer. I hate a universe that metes out morbidity and mortality like a casino dealer. I’d much prefer a cosmos where randomness were a bit player. I hope another study quickly comes along to counter that one. Until it does, I wish I knew which eating strategy – savoring gribenes, denial or “everything in moderation” – will do me less harm than good.

But even if everything really is a crapshoot, I gotta tell you: Kraft Singles are off the table.