Eating foods high in fat is important on a ketogenic diet. However, not all fats are created equal. Many people enjoy using cooking oils to prepare food, but the type of oil and the fats it contains can be the difference between a healthy and unhealthy meal. Before you heat up the frying pan, take time to consider which oil will complement both your meal and ketogenic lifestyle.
What Makes a Cooking Oil Good for You?
When choosing a cooking oil, there are two main factors to consider: the level of refinement during production (less is generally better) and the type of fat the oil consists of, which determines how it responds to heat.
Cooking oils change their chemical structure when they’re heated (a process that’s known as oxidation) and release toxic products that can cause harm to your body. An oil that’s stable at room temperature can lose its stability during cooking. In general, oils that are rich in polyunsaturated fats produce more oxidative products than those that contain more monounsaturated or saturated fats, so it’s better to avoid or limit their use.
Healthy cooking oils rich in saturated fat are found in fruits — olives, avocados, and coconuts — rather than highly processed nuts and seeds. These oils can easily replace the standard canola or vegetable oils used in everyday cooking.
What is Smoking Point? Does It Matter?
The smoking point is the temperature at which cooking oils breakdown and turn into smoke. Highly refined and processed cooking oils have a high smoke point, whereas most unrefined oils have a low smoke point. Overheating a cooking oil leads to the destruction of beneficial nutrients and the creation of free radicals. Judging the viability of low and high temperatures depends on the cooking activity:
- Pan-frying (sauté) on stovetop heat: 248 °F
- Deep frying: 320 °F – 356 °F
- Oven baking: 356 °F
The table below displays the smoking points of cooking oils mentioned in this article (source: Wikipedia).
Smoking Point Temperatures of Cooking Oils
| Cooking Oil | Smoking Point Temperature (Fahrenheit) |
|---|---|
| Extra Virgin Olive Oil | 320 °F |
| Avocado Oil | 520 °F |
| Virgin Coconut Oil | 350 °F |
| Ghee | 482 °F |
| Butter | 302 °F |
| Sunflower Oil | 441 °F |
| Corn Oil | 446 °F |
| Soybean Oil | 453 °F |
| Vegetable Oil | 448 °F |
Healthy Cooking Oils
Extra Virgin Olive Oil
This oil is made of pure, cold-pressed olives without extra chemical or industrial processing — important because additional processing lowers its nutritional value. It contains a compound called “oleocanthal”, which has been proven to have similar anti-inflammatory effects as ibuprofen.
Olive oil has a mild, distinct flavor that’s great for green salads and vegetables, cooked or raw. Since it has a relatively low smoke point, olive oil is best suited for sautéing and low-heat baking.
Avocado Oil
Avocado oil is relatively new in the culinary world, but it has quickly become a favorite due to its beneficial properties. It’s rich in monounsaturated fat and vitamin E and has an unusually high smoke point, which makes it great for high-heat pan frying and oven roasting.
Virgin Coconut Oil
Virgin coconut oil is unrefined and extracted from the fresh milk of the coconut (as opposed to the dried kernel used in the production of coconut oil). The lauric and capric acids, the major fatty acids found in coconut, have been proven to have antibacterial, antiviral, and antiprotozoal properties. Some have even referred to it as a “drugstore in a bottle” because of its antioxidant effects.
This versatile oil is stable at high temperatures and is often used to sauté, fry, and bake. However, its strong coconut flavor may be too much for some, so many people prefer to use it for desserts and certain savory dishes.
Butter/Ghee
Butter and ghee are very similar in their content since they’re both rich in monounsaturated and saturated fatty acids. Ghee doesn’t contain the milk proteins present in butter, which become denatured at high temperatures. This makes ghee better for high-heat cooking. Butter, on the other hand, has a lower smoke point and can be used for sautéing and low-heat cooking.
Butter and ghee are nutritious and typically cheaper than several other options on this list. They’re rich in flavor and make a good staple in place of unhealthier oils.
Unhealthy Cooking Oils
Sunflower Oil
Sunflower is one of the most widespread, easily accessible oils. This oil is rich in linoleic acid (an omega-6 fatty acid), which can be inflammatory. While the body needs these fatty acids as well, the ratio is important. Many people eat a diet that’s lacking the proper amount of omega-3 fatty acids.
Unfortunately, omega-6 fatty acids are present in many other processed foods. If over-consumed, this can increase inflammation and lead to further health issues. It’s better to avoid sunflower oil for this reason.
Corn Oil
Corn oil is made by extracting oil from the germ of the corn. It’s highly refined, very cheap to produce, and has a high smoke point, making it a popular frying oil. When heated, corn oil releases high levels of the oxidative product known as aldehydes. These highly reactive compounds can interfere with enzymes and hormones in your body.
Corn oil is a common ingredient in processed foods like cookies, candy bars, and granola. Healthy substitutes can be made with coconut oil and many grocery stores carry these alternatives nowadays.
Soybean Oil
Soybean oil is just as widely used as sunflower oil, and it’s just as bad (if not worse) for your health. In some people, a high intake of phytoestrogens can negatively impact thyroid function. Moreover, studies conducted in mice have shown that soybean oil is one of the major contributors to the obesity epidemic in the United States and can negatively impact genes linked to inflammation, diabetes, and cancer.
Vegetable Oil
Oil producers use “vegetable oil” as a catch-all phrase to refer to oil that’s made of one or more blends of different vegetable oils. This can include soybean, rapeseed, canola, or corn oil. Vegetable oils are highly processed and have significantly reduced antioxidant content. They also have high levels of polyunsaturated fats (usually two-thirds of their composition), which produce many toxic by-products during the cooking process.