We all know that the type of oil you use can make or break a dish—and as it turns out, it can also impact your health and waistline. While certain oils like olive or avocado oil are known for their anti-inflammatory and heart-healthy benefits, other staples in your kitchen may be doing more harm than good. In fact, some of the most common cooking oils you’ve got in your pantry could be increasing your risk of inflammation, disrupting metabolism, and even contributing to unwanted weight gain.
We spoke to health experts to highlight a few of the worst inflammatory oils out there, from sunflower and corn oil to less obvious culprits like cottonseed and palm oil. Find all of their warnings below.
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1. Corn oil
Many commercially processed corn oils may contain trans fats. Trans fats raise LDL cholesterol while lowering HDL (good) cholesterol.
Dr. Peter Brukner, nutritionist, dietitian, and author of Fat Lot of Good, elaborates on this type of oil and reveals, "Even though corn oil is often sold as a healthy option, it can make trouble when you cook with it. When you heat corn oil, it makes free radicals. These are unstable molecules that can harm your cells, including the ones in your heart. This makes the oxidative stress in your body go up, which can cause inflammation." The high amount of omega-6 polyunsaturated fats and calories can also contribute to weight gain.
2. Sunflower Oil
Sunflower oil is another potentially inflammatory vegetable oil that may be best to avoid if you're watching your weight. Like other oils, the omega-6 fatty acid content could support your body's inflammatory response, especially if your diet is low in omega-3 fatty acids.
"When eaten in large amounts, it can result in calorie consumption greater than an individual’s energy needs," Stephani Johnson, D.C.N., R.D.N tells Prevention.com. "This contributes to weight gain, increasing the risk of overweight and obesity, and their related health issues."
Choose high-oleic sunflower oil, which contains more monosaturated fats, whenever possible for a healthier choice.
3. Soybean oil
You may have noticed that soybean oil is a common ingredient in many processed and fast foods. These foods are almost always high in calories, low in nutritional value, and contribute to unhealthy eating habits. Just like the other oils on this list, soybean oil’s inflammatory effects can contribute to heart disease and weight gain.
"Soybean oil is present in many foods that are processed, but it’s not very good for your heart. Similar to vegetable oil, soybean oil contains a lot of omega-6 fats, which lead to inflammation. With time, this can harm the inside of your arteries and cause plaque to build up. This makes it more difficult for your heart to move blood. Also, many kinds of soybean oil have bad trans fats that increase your 'bad' cholesterol," says Dr. Brukner.
3. Canola oil
Canola oil is a popular option that’s often marketed as a heart-healthy choice because of the low saturated fat content. However, this type of oil is high in omega-6 fatty acids, which, while essential in moderation, can increase inflammation and and add inches to your waist when consumed in excess or not balanced with omega-3 fatty acids. "Canola oil is not heart-healthy as advertised. It is highly processed, contains trans fats, and promotes inflammation. It should be avoided," says Dr. Ralph Waldo.
4. Cottonseed oil
Cottonseed oil is another one that is rich in omega-6 fatty acids. An imbalanced intake of omega-6 relative to omega-3 fatty acids can lead to chronic inflammation, a potential factor in the development of cardiovascular issues and unwanted weight gain. "Cottonseed oil is a byproduct of the cotton industry that is highly processed and inflammatory. It is used in snack foods and should be eliminated from the diet," says Dr. Waldo.
5. Lard
Lard has a high content of saturated fat, and saturated fat has been linked to increased levels of LDL (bad) cholesterol and weight gain. "Lard is a rendered pig fat and is high in saturated fats. While it contains some monounsaturated fats (similar to olive oil), the high saturated fat content can raise LDL ("bad") cholesterol. It contains around 40% saturated fat, which may result in plaque buildup in arteries (atherosclerosis), restricting blood flow, and increasing the risk of heart attacks and strokes," says Catherine Gervacio, registered dietitian and nutrition writer for Living.Fit.
7. Palm oil
Gervacio says to use palm oil in moderation because this type of oil is known to contribute to chronic inflammation in the body—a major cause of weight gain. As for heart health, the high omega-6 fatty acids can come with a risk, as she notes, "Inflammation plays a key role in the development of various cardiovascular diseases and metabolic disorders, including type 2 diabetes. It also contains a higher ratio of omega-6 fatty acids relative to omega-3s. Consuming excessive omega-6 fats while having low omega-3 intake can promote inflammation, further increasing the risk of chronic diseases, including heart disease."
