We’ve been obsessed with fat for more than half a century. And this spring, the fervor hit a new level. Headlines screamed “Butter Is Back,” “Bacon Is Good for You” and “Ending the War on Fat”—stories suggesting everything we’d known was wrong and that we’d done a nutritional one-eighty on fat. So, understandably, a lot of questioning hands shot up in the air. Yours was likely one of them. Does this mean Julia Child—the original queen of butter and foie gras—had it deliciously right all along? Are we moving away from the idea of good and bad fats? Should we embrace marbled beef? Most of all, what does a heart-healthy diet look like now?
That feeling of being nutritionally adrift is understandable. After all, our aversion to so-called artery-clogging fatty foods—if not flat-out fear—is as ingrained as the advice to get eight hours of sleep a night and exercise regularly. It all started back in the 1950s, when scientist Ancel Keys made headlines by discovering that saturated fat raised cholesterol levels. Since cholesterol was known to increase heart disease risk, the logic went, we should avoid foods with saturated fat—and shortly thereafter, dietary guidelines were born and the idea of eating low-fat took off.
Then, about 15 years ago, the concept of “good” and “bad” fats was introduced. We were told to be eagle-eyed about saturated fat—trans fat joined the no-no list a few years later—and to embrace unsaturated fats like oils, nuts and avocados. So when a recent study in the Annals of Internal Medicine concluded that saturated fat does not, in fact, appear to increase heart disease risk (and sparked those headlines), our collective jaws hit the floor. Wait, what?! How could this be? The researchers analyzed data from 76 studies involving more than 600,000 people and found that those who ate the most of this so-called “bad” fat did not have a higher risk of cardiovascular disease than those who ate the least. (Trans fats remain a villain: in the study, they were associated with a higher risk.)
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Is Bacon Beneficial?
So should we end the war on fat? You’ll find answers on the next few pages. But first, let’s dispel one key myth about the Annals study: despite the news headlines, no one (at least in nutrition circles) is saying that all saturated fat is healthy. “Lack of harm is not the same thing as being beneficial,” explains David Katz, M.D., M.P.H., director of the Yale University Prevention Research Center and an EatingWell advisor. “We found saturated fat is on average neutral compared to everything else we eat—it doesn’t seem to affect heart disease risk,” adds Dariush Mozaffarian, M.D., Dr.PH., dean of the Friedman School of Nutrition Science and Policy at Tufts University and a co-author on the study.
Now to the question on every omnivore’s mind: How could this be? Was the research that has informed our eating habits that wrong? Not entirely. “Our initial science was just focused on ‘bad’ LDL cholesterol—and showed that saturated fat raises LDL levels, which in turn raises heart disease risk. That’s all the evidence we had,” says Mozaffarian. “But nutrition science—which isn’t even 100 years old—has advanced rapidly, and the data has changed.” It’s true that sat fat raises LDL cholesterol; that finding from the 1950s holds up. But what researchers have since discovered is that it also raises HDL, the “good” cholesterol. And saturated fat does not increase the number of LDL particles, one of the most important predictors of cardiovascular risk. Saturated fat makes LDL particles larger and that’s pretty benign in terms of cardiovascular disease.
Goodbye to Good and Bad
It’s worth noting, too, that this isn’t some newfangled theory. Evidence that saturated fat may not raise heart disease risk has been in the literature for decades. It’s just that 2014 happened to be the year it went viral. To be sure, the issue is still being studied—and debated. Not everyone agrees on the degree to which saturated fat impacts our health. But, for now, the bottom line appears to be this: “We’ve evolved our thinking and the ‘good’ and ‘bad’ stuff has got to go,” says Pamela Peeke, M.D., clinical assistant professor at the University of Maryland School of Medicine. “Let’s think in terms of beneficial and not-so-great. There is no bad, except for trans fats.”
There is even preliminary evidence that suggests some types of saturated fat may be more neutral than others—and possibly even beneficial. Stearic acid, a kind of saturated fat in dark chocolate and beef, for example, has been shown to have no heart-harmful effects, notes Katz. And, in the context of an overall healthy diet, it may possibly offer some pros: a recent study in the Journal of Human Hypertension found that a DASH-style diet (low in salt and sugar, rich in fruits, veggies and whole grains) that swapped in lean beef as the main protein source (about 4 ounces a day) lowered blood pressure and improved blood vessel function. An earlier study concluded that a similar diet can also improve cholesterol levels.
Then there’s coconut oil. It was once demonized for its super-high sat-fat content (92 percent!). But the kind of fat it’s primarily composed of (lauric acid) now appears to have no impact on cholesterol. There’s also mounting evidence that full-fat dairy products may actually improve your health compared to low-fat. Still, this is complex stuff—because, as Mozaffarian points out, foods like beef, dairy, nuts, tropical oils and vegetable oils contain multiple types of saturated and unsaturated fats, and how the body reacts to them (not to mention the other nutrients in the food) can impact their health effects. At the moment, there’s no need to get in a twist about specific saturated fats until scientists sort out more of the details.
Replace with Something Worse
The Annals study also sparked a serious conversation about another health issue at play: what replaced the fat in our diets when we banished it. We started eating more sugar and processed carbohydrates. “We replaced one thing with something worse,” says Mozaffarian. “These types of refined carbs do lower LDL levels, but they also lower HDL levels and increase triglycerides [a type of fat in your blood]. They’re also linked to higher blood glucose and weight gain. So we’re not just talking about an increased risk of heart disease, but also obesity and diabetes.” That may be part of the reason why the group in the Annals study who ate the least saturated fat didn’t have lower rates of cardiovascular disease than those who ate loads of it—because they were subbing in unhealthy processed carbs and sugar instead.
It also helps explain why, despite the fact that we’ve lowered our saturated fat intake over the past several decades, obesity rates have continued to climb and heart disease is still our number-one killer. “What the study really tells us is that there’s more than one way to eat badly,” says Katz.
The Right Amount of Fat
So what, exactly, should we be eating, given all this new evidence? A diet that’s almost forehead-smackingly simple—and which most experts agree on, no matter where they fall on the saturated-fat issue: eat a diet rich in a variety of fruits, nuts and vegetables, some healthy protein like fish, poultry and dairy, and minimally processed, whole-grain carbs—the kind that are high in fiber and have been fiddled with the least, like brown rice and whole-wheat bread. Also key: limit sugary foods and processed carbs like white bread, white rice and low-fiber breakfast cereals. If it has a lot of unpronounceable ingredients and a long shelf life, keep walking. (Any of this sounding familiar?) And fats? How should we think about those?
For the record, the Dietary Guidelines for Americans recommend limiting saturated fat to less than 10 percent of total daily calories—and instead emphasizing foods containing unsaturated fat. Eating way more of these genuinely healthy fats than saturated ones is advice worth following. But many experts have a different take: “We shouldn’t be thinking about fat at all,” says Mozaffarian. “It’s about the overall quality of the foods you eat. Depending on the foods you choose, you can eat a low-fat diet that’s terribly unhealthy and raises your heart disease risk, and you can eat a high-fat diet that does the same, or you can eat very healthy versions of either.”
He and other experts believe we get too hung up on grams and percentages, and what we really need to do is take a big-picture view of what we’re eating. “Foods are complicated,” explains Mozaffarian. “We can’t just look at one aspect and judge their overall healthfulness.” Katz agrees: “It’s time to stop focusing on macronutrients like fat and think in terms of what should make up the majority of your diet. If you do that, you can’t go too far wrong.” So... if you want to have the occasional cheeseburger, it’s fine.
Looks like Julia Child was onto something, after all. Her wise words: “I think one of the terrible things today is that people have this deathly fear of food: fear of eggs, say, or fear of butter. Most doctors feel that you can have a little bit of everything.”
Shaun Dreisbach is a Vermont-based writer who specializes in health and fitness.