Eating the right kinds of fats feeds both the body and brain, all while keeping us full longer, so we’re not as tempted to overeat or binge on sugary, crash-inducing snacks.
In fact, studies have shown no evidence of a link between how many daily calories a person gets from fat, and how likely they are to gain weight or develop heart disease. Besides, when food manufacturers lower the amount of fat in a food, they typically up the sugar and carbohydrates instead, so it’s better to embrace the role of fat in your diet instead of swapping it out for more sugary, cakey sweets.
But don’t assume that just because fats serve an important role in fuelling the body and protecting cells that you have a free pass to slather a layer of lard on everything you eat, or consume large portions of red meat every day.
Not all fats are created equal. Some can help your heart stay healthy, while others can do real damage to the body, increasing the risk of heart disease and early death.
Here’s how to choose the right fats.
We know some fats do damage to the body. One of the worst offenders is trans fat.
Trans fats come from both artificial and natural sources.
Artificial sources of trans fat include vegetable oils that are laboratory-heated to prevent spoilage, as well as deep-fryer oils, margarines, and packaged foods like frozen pizzas and cookies.
Researchers estimate that during the heyday of trans fats in the 1990s, they led to roughly 50,000 preventable deaths every year in the US.
The FDA rolled out a near-universal ban on trans fats in June.
“There’s clear evidence that trans fats are bad,” said professor Gary Fraser of the Loma Linda School of Public Health, who’s studied fats for decades.
Some small amounts of trans fats are naturally found in some meat and dairy products like butterfat and beef, but it’s not clear whether they are as harmful as artificial trans fats.
Many food manufacturers have replaced artificial trans fats with interesterified fat, which may not be any better.
Interesterification is a process a lot like hydrogenation that rearranges fatty acids to change a fat’s melting point – or to make it last longer without spoiling.
One small study of 30 people released in 2007 raised serious alarm bells when it suggested that interesterified fat might help raise blood sugar levels, while also lowering “good” HDL cholesterol. (The interesterified fats used in that study were much more potent than a lot of what’s on the market today, so it’s hard to know if they’d have a similar effect on consumers.)
Still, it’s clear from numerous otherstudies that we don’t yet know enough about the long-term effects of interesterified fats on our bodies and our immune systems. It’s probably best to stay away from the fats, when you can, and generally avoid processed foods whenever possible.
Saturated fat isn’t quite as bad as trans fat, but it’s good to limit intake of saturated fats from things like red meat, coconut oil, and cheese.
Most naturally-occurring saturated fats come from animal sources, like beef, pork, skinned poultry, butter, cream, and cheeses.
The popular notion that saturated fatty acids in coconut oil may be good for you is not backed up by sound science.
Karin Michel, a professor at the Harvard TH Chan School of Public Health, is not a fan of the coconut oil trend. She argues that the saturated fat content in the oil is worse for your arteries than lard.
“Coconut oil is pure poison,” she said in a recent lecture.
Michel thinks it’s “one of the worst foods you can eat,” and points out that there’s really no evidence that coconut oil has any significant health benefits. So it’s probably best not to have much of the stuff at all.
One 2010 Harvard study found that people who swapped out saturated fat for polyunsaturated fat in their diets reduced their risk of developing heart disease by 19%.
There are good fats out there. Some of the best fats are monounsaturated fats that come from plant sources.
Plant-based oils that are liquid at room temperature, as well as nuts, nut butters, seeds, and avocados all carry high doses of monounsaturated fat.
Like the name indicates, monounsaturated fats are fat molecules containing one (unsaturated) carbon bond. They come from plant sources, and include many liquid-at-room-temperature oils like olive, peanut, and sesame.
One of the reasons that monounsaturated fats like those found in nuts and seeds are so good for you is because they can actively lower your bad, LDL cholesterol. They do this while adding a dose of Vitamin E to your diet, which keeps your eyes and your immune system healthy.
Source: American Heart Association
Polyunsaturated fats are good for us, too. Like monounsaturated fats, foods high in polyunsaturated fats include many oils that are liquid at room temperature.
They too help lower bad, LDL cholesterol levels. Foods high in polyunsaturated fat content include fish, sesame seeds (and tahini spread) chia, and flax, as well as many nuts.
Some of the best polyunsaturated fats are omega-6 and omega-3 fatty acids. These fats help repair and build our cells, reduce instances of heart disease, and can also have anti-inflammatory effects. They are essential fats the body can’t produce on its own.
Omega-6 fatty acid-rich foods include sunflower seeds, pine nuts, sunflower and soybean oils, and pecans.
Omega-6 fatty acids can help control your blood sugar and may reduce your risk for developing diabetes.
Source: National Institutes of Health
Omega-3’s are likewise great fatty acids. They can reduce the risk of abnormal heartbeat, slow the rate of heart-clogging plaque growth, reduce the amount of fat in your blood, and lower blood pressure a bit.
For these reasons, The American Heart Association recommends adults eat oily fish twice a week or more.
“Fatty fish like salmon, mackerel, herring, lake trout, sardines and albacore tuna are high in omega-3 fatty acids,” the AHA says.
Foods rich in omega-3’s include walnuts, flax seeds and their oils, as well as oily fish like salmon and albacore tuna.
Scientific studies suggest omega-3’s may even slow cognitive decline in older adults without dementia.
Source: National Institutes of Health
Eggs, chicken, and beef also have some omega-3’s on board.
New research suggests that foods like nuts and seeds may be heart-healthy not simply because of their mono and polyunsaturated fat content, but also because they’re infused with more heart-helping proteins than, say, a piece of red meat.
Professor Gary Fraser from Loma Linda University has been studying fat for more than 20 years, and says that while low-fat diets clearly aren’t the catch-all answer to a healthy diet, the solution is not to consume more fatty animal products, which can hurt heart health.
Instead, he suggests a plant-based, Mediterranean style diet, which is many dietitians’ favourite suggestion too.
“There’s clear evidence that trans fats are bad, probably saturated fats are bad, but the monos and the polys really shouldn’t be under the microscope,” Fraser said. “I think the focus should be on very low meat, or no meat, and lots of vegetables and nuts and seeds.”
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