By Melissa Kravitz

In the second edition of the U.S. Department of Agriculture's (USDA) Dietary Goals for the United States, published in 1977, Americans were advised to limit their intake of fats, replacing their regular fat sources (meat, butter) with complex carbohydrates and manufactured substitutes (margarine).

And just as low-fat, fat-free and "lite" products began cluttering grocery shelves with their fat-less promises and shiny packaging tempting grocery shoppers to pick the skinnier, chicer lifestyle purchase, obesity rates began to grow and eventually soar in the U.S.

Avoiding fats has made America even fatter than before.

The percentage of Americans who are obese has been steadily increasing since the low-fat campaign began in the 1970s. National Institutes of Health

"The 40-year-old campaign to create low- and nonfat versions of traditional foods has been a failure: We've gotten fat on low-fat products. Why? Because removing the fat from the foods doesn't necessarily make them nonfattening. Carbohydrates can also make you fat and many low- and nonfat foods boost the sugars to make up for the loss of flavor," Michael Pollan explains in Food Rules. "By demonizing one nutrient—fat—we inevitably give a free pass to another, supposedly 'good,' nutrient—carbohydrates in this case—and then proceed to eat too much of them instead."

Since the low-fat campaign began in the late 1970s, Americans have actually been eating more than 500 additional calories per day, most of them in the form of refined carbohydrates like sugar. The result: The average man is 17 pounds heavier and the average woman 19 pounds heavier than in the late 1970s. The takeaway here is that you're better off eating the real thing in moderation than bingeing on lite products packed with sugars and salt.

A 2015 study conducted by American and British doctors concludes that the dietary fat recommendations introduced to 220 million Americans and 56 million UK citizens in the late 1970s and early '80s were completely unsubstantiated by clinical trials. As a result, "clinicians may be more questioning of dietary guidelines, less accepting of low-fat advice (concomitantly high carbohydrate) and more engaged in nutritional discussions about the role of food in health."

The Spread of the Low-Fat Myth

Intuitively or at least to those not versed in nutrition and medical science, eating less fat to be less fat may add up. And when politicians and the media perpetuate this myth, one can see how easy it is to buy into. When low-fat snacks are sitting next to traditional packaged cookies on the shelf, just feet away from the aisle-cap magazine boasting the newest tricks to eat less fat, what are Americans going to buy?

In the February 2008 article How the Ideology of Low Fat Conquered America, published in Oxford's Journal of the History of Medicine and Allied Sciences, scientist Ann F. La Berge points to popular 20th-century magazines like Prevention, Family Circle and the now-defunct Ladies' Home Journal, as well as the New York Times, for popularizing the half-baked science that low-fat foods were the solution to America's weighty woes. Combine the ever-steady stream of articles on how to eat less fat with clever marketing and tasty products like Snackwell's line of low-fat baked goods and it's easy to see how America ate into the myth.