For decades, health organizations and governments have encouraged people to limit how much fatty foods they eat. Now, it looks like the U.S. government is slowly retreating from its low-fat diet crusade to realign its views with modern science.

Every five years, the U.S. government issues updated dietary guidelines and will release new ones this year. In a preliminary report in December, an advisory panel said dietary cholesterol is no longer "considered a nutrient of concern for over-consumption," and that finding is expected to be part of its new guidelines, which are expected shortly.

The last set of guidelines, issued in 2010, instructed people not to consume more than 300 milligrams of dietary cholesterol daily.

Dietary cholesterol comes only from animal products — like eggs, dairy, fish and meat. But the body also makes cholesterol, a waxy substance that can clog arteries, from certain types of fat and the health concerns about ingesting too much saturated and trans fats in particular are still in place. 

Under the old guidelines, a large egg has 186 mg, according to the U.S. Department of Agriculture. Add two slices of cheddar cheese and two tablespoons of salted butter to that and you've surpassed the daily limit.

However, despite setting clear limits on dietary cholesterol in 2010, the U.S. backed away from doing the same for total fat consumption.

Previous reports had included a maximum percentage of a person's daily calories that should come from fats.

'Soft science' sparked low-fat policies

This slow tip-toeing away from the glorified low-fat diet, by eliminating maximum cholesterol and fat intake recommendations, points to "the overall soft science that has been behind our nutrition policies for so many decades," says Nina Teicholz, author of The Big Fat Surprise: Why butter, meat & cheese belong in a healthy diet.

Nina Teicholz

Nina Teicholz is the author of The Big Fat Surprise: Why butter, meat & cheese belong in a healthy diet. (Nina Teicholz)

The low-fat trend all started with a persuasive physiologist in the mid-1900s by the name of Ancel Keys, many nutritionists say. Legend paints him as the kind of man who could convince anyone of anything.

In the midst of America's rising panic about heart disease, which was suddenly killing large numbers of men — even then president Dwight Eisenhower suffered a heart attack that sidelined him for several days — Keys became determined to prove that fat and cholesterol consumption were at the root of the problem.

He secured funding for an epic Seven Countries Study that surveyed 12,000 men and their dietary habits to show that countries with high-fat diets had more cases of high cholesterol levels and heart attack deaths.

Keys's study was highly flawed and ignored some contradictory research, Teicholz says. Regardless, his findings showed a link between high-fat diets and poor health, and in 1961, he convinced the American Heart Association to recommend Americans eat less fatty foods.

"The American Heart Association guideline is what was the little, tiny acorn that grew into the giant oak tree of recommendations we have today," says Teicholz. "And it became dogma."

The U.S. government issued its first low-fat diet recommendation in the 1980s.

Low-fat diets 'useless'

Those policies prompted Americans — and others, like Canadians, whose governments were using the same findings to promote low-fat meals — to load up on carbohydrates.

In 1992, the U.S. Department of Agriculture released a food pyramid that showed how much of each food group people should eat daily. Bread, cereal, rice and pasta claimed the largest spot at the bottom with six to 11 recommended servings.

Food pyramid

In 1992, the U.S. Department of Agriculture released this food pyramid, which was eventually replaced in April 2005 by MyPyramid. (U.S. Department of Agriculture)

"So, it was get rid of meat, butter, dairy, cheese, eggs and switch over to pasta, grains, rice, potatoes — and those are all carbs," says Teicholz.

Over the next 35 years, Americans started eating about 25 per cent more carbohydrates than they did before, she says.

Recent scientific research, as well as previously ignored research that has since been re-examined, shows little support that a low-fat diet is healthier.Unfortunately, it turns out that carbohydrates are uniquely fattening, she says, because they skyrocket a person's blood sugar temporarily and when it plummets, they're hungry again. 

Clinical trial evidence shows a low-fat diet is "at best useless" at preventing obesity, diabetes, cancer and heart disease, says Teicholz, "and at worst, possibly provoking them."

Bad versus good fats

Recent studies have shown a diet that restricts carbohydrates is more effective in fighting obesity, controlling diabetes and managing heart disease, she says.

The U.S. government seems to be following this shift in thinking. The U.S. Department of Agriculture replaced the carbohydrate-heavy pyramid in April 2005 with MyPyramid, which suggested adults consume at least three ounces of whole grains each day. The U.S. dietary guidelines no longer include daily fat intake maximums and may soon eliminate suggesting a maximum intake for dietary cholesterol, too.

"We know fat is essential. Fat is important in the diet," says Cara Rosenbloom, a registered dietitian. "We just have to make sure we're eating the right fats."

There are many different kinds of fats, but man-made trans fat is "the number one bad fat," she says. It's found in processed foods like baked goods or snack foods, and is often labelled as partially hydrogenated oil or hydrogenated oil.

She encourages people to stay away from trans fat, but include good fats in their diet by eating more whole foods. Then they'll naturally consume good fats, including:

  • Olive oil or oils derived from nuts and seeds.
  • Fatty fish, like salmon, mackerel, rainbow trout, sardines or tuna.
  • Nuts and seeds.

"It's kind of getting back to basics," she says of eating more natural and less packaged foods. "Then the type of fat naturally just works out to be better for you. There is no trans fat in a diet that's like that. There's no hydrogenated fat in a diet that's like that."