The One Thing You Need To Know About Healthy Fats, According To An MD

Healthy fats have become more a part of diet trends in recent years, and the era of low-fat and fat-free diets has waned in favor of options like the keto diet and the Mediterranean diet—which advises 35% of the diet be made up of fats. But how can we know if a fat is a "healthy" option, other than reading its name on a list?

"Nature does not make an unhealthy fat," says Cate Shanahan, M.D., in her appearance on the mbg podcast. "We do, in our factory. "

"If we're talking about fat that's a whole food, that's good," she explained. "That's natural fat, and human beings have been consuming it since there were human beings."

So the real key? Whole-food-based fats. Yep, when it comes to healthy fats, it's not that different from defining healthy foods: The closer something is to its natural form, the healthier it is.

The buzziest healthy fats have their own sort of superfood status, like coconut and avocado, but "eggs, cheese, dairy fat, animal fat," can be part of a diet with healthy fats, too.

Even butter, which certainly doesn't get called a superfood, can be a healthy fat: really, it's just "two simple steps away from milk. You don't need high heat, refining machinery," to get to butter, explained Shanahan.

In the world of oils, it's not as simple as buying a bottle labeled "olive oil" or "coconut oil" to get the benefits of that healthy fat superfood.

"Olive oil, you start with plump green olives and the oil squirts out," says Shanahan, "you collect it all...it's dark green and full of sediment in it and loaded with antioxidants and minerals. That's good stuff." That's part of why extra-virgin olive oil is prized—in its virgin form, it's packed with the most nutrients that make it a good fat.

Another oil that keeps its healthy quality well? "Avocados are also fruit," she says. "It's very easy to get the oils from these things."

But on the other end of the oil spectrum, "There's a quality of olive oil that is so bad, called lampante1, that we put it in lamps and burn it," she says. "Good for fuel but not good to consume. The problem comes down to the taste and structure of the olive oil, which in lampante olive oils is so poor, it's literally deemed not fit for human consumption.

"You can get every last drop out of the original product in such a way that you're damaging it, and when you refine it, you strip away all the beneficial antioxidants, nutrients, and minerals," explained Shanahan.

According to Shanahan, the oils to look out for are the ones that are most processed most often—seed oils, in particular, don't make the cut for the "healthy fat" title. "Nature doesn't make stupid things," she says, a good reminder that focusing on a diet of whole foods extends past just produce and snacks to our cooking oils too.