Gone are the days when all fats are bad.
Low-fat diets have—for the most part—been knocked off their health pedestal because health experts now know that eliminating fat altogether is not the healthiest choice. In fact, dozens of studies have found that low-fat diets are no better for your health than moderate or high-fat diets, and for many people, they may be worse, according to Dr. Walter Willett of Harvard University’s School of Public Health.1
It’s been nearly four decades since the low-fat diet craze swept through, and today there are types of fat that we’re actually advised to eat on the regular (we’re looking at you, omega-3 fats!).2,3
Yes, some fats are still less worthy (health-wise) than others. Trans fats are an absolute no-no and saturated fats (think: butter, red meat, etc.) should be limited to no more than 10 percent of your diet, per the Dietary Guidelines for Americans.4 (The American Heart Association advises a lower cap of 5 to 6 percent of your diet from saturated fat.5)
But 20 to 35 percent of your diet should be healthy fats.6 What are those healthy fats, what makes them good for you, and which foods are considered healthy fats?
The Healthy Fats—and Where to Find Them
How fats differ is based on their chemical structure (i.e., how they’re built). Then, based on how they’re built, they function differently in the body. All fats are made up of a chain of carbons with hydrogen atoms attached. The so-called healthy fats are unsaturated, which means that not all of the carbons are linked to (or “saturated” with) hydrogen atoms.7 This structure is also what makes unsaturated fats, like oils, liquid at room temperature.
Then, within the category of unsaturated fats, there are two main subcategories—monounsaturated fats and polyunsaturated fats.
Foods rich in monounsaturated fats include5,8:
- Olive oil
- Canola oil
- Peanut oil
- Tree nuts, such as almonds, cashews, hazelnuts, pistachios, and pecans
- Peanut butter
- “High-oleic” safflower and sunflower oils
Foods rich in polyunsaturated fats include:
- Corn oil
- Soybean oil
- Sunflower seeds
- Hemp seeds (and their oil)
- Chia seeds (and their oil)
- Flax seeds (and their oil)
- Oily, cold-water fish (salmon, tuna, mackerel, herring, trout, sardines, anchovies, etc.)
Why Healthy Fats Are Healthy
Both monounsaturated and polyunsaturated fats have heart health benefits, though polys seem to have a slight edge over monos. That conclusion stems from studies where participants cut back on their saturated fat intake and replaced it with either mostly polyunsaturated fat or mostly monounsaturated fat. When experts reviewed those studies, they concluded that polyunsaturated fats were better at lowering “bad” LDL cholesterol, as well as the risk of developing heart disease.
There’s also a type of polyunsaturated fat that is particularly healthy: omega-3 fatty acids. A lot of scientific data shows omega-3s have brain- and heart-health benefits, as well as other potent anti-inflammatory properties that are beneficial for various conditions.3 Hemp seeds (and the oil made from hemp seeds), as well as chia, flax, and walnuts all contain a plant-based version of omega-3 fat called ALA. Although ALA isn’t considered as beneficial for your health as other omega-3 fats EPA and DHA, ALA is the form of omega-3 that’s most common in our diet (from there your body converts it to EPA and DHA). For EPA and DHA, look to oily, cold-water fish and seafood. Hemp—as well as other plant-based sources—are said to be ‘cleaner’ sources of omega-3 fats because fish get their omegas from eating microalgae and microalgae can concentrate toxins and heavy metals.