For decades, it’s been nearly impossible to miss the message that fat is bad: The more we banished fat from our plates, the better off (thinner, healthier) we’d be. Eating fat, we were told, made you fat and increased the risk of heart disease and other illnesses.

That notion really took hold following the release of a 1977 Congressional report called “Dietary Goals for the United States,” which suggested Americans eat less fat; the National Institutes of Health soon joined the low-fat chorus. Food manufacturers raced to create low-fat processed food products — Snackwells, anyone? — to take advantage of Americans’ shifting eating patterns.

But once we started eating less fat, it was inevitable we’d start eating more of something else. Carbohydrates started taking up a larger and larger portion of our meals. Today, more than half of the average American’s daily caloric intake comes in the form of carbohydrates — twice what nutritionists recommend. Over the years, annual grain consumption has risen by almost 60 pounds per person, according to a story called “What if It’s All Been a Big Fat Lie?” in the New York Times. We also started eating more total calories — 400 more a day — perhaps, in part, because fats are more filling than other foods. Without them, we’re hungrier.

But we didn’t get thinner or healthier; in fact, what’s come to be called “the obesity epidemic” started just a few years later, in the early 1980s. While Americans ate less fat, the percentage of obese Americans, which had previously hovered around 13 percent, shot up to about 25 percent by the late 1980s. Diabetes and heart disease rose, too.

So fat’s reputation is starting to be rehabilitated, while carbohydrates come into the crosshairs. “Fat is not the problem,” Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health, told the Los Angeles Times in “A Reversal on Carbs.” “If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugary snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases.” Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health, told that newspaper, “The country’s big low-fat message backfired. The over emphasis on reducing fat caused the consumption of carbohydrates and sugar in our diets to soar. That shift may be linked to the biggest health problems in America today.”

Even the designation of good and bad foods is turning out to be overly simplistic, as different kinds of fats can be found in most foods. That’s good news for beef. Much of beef’s fat is unsaturated, but, according to the New York Times article, even the rest of its fats are not simply bad: “…even saturated fats…will elevate your bad cholesterol, but they will also elevate your good cholesterol. In other words, it’s a virtual wash… More than two-thirds of the fat in a porterhouse steak, for instance, will definitively improve your cholesterol profile… If you work out the numbers, you come to the surreal conclusion that you can eat lard straight from the can and conceivably reduce your risk of heart disease.”

So perhaps eating fat doesn’t necessarily make you fat, or unhealthy, after all — but that message might take a few years to sink in with consumers who are used to looking for the low-fat label.