Fats and oils on keto can be a slippery slope on any diet, and with oils becoming a huge part of our daily diet, this topic is of increasing interest. Most of the calorie content within processed foods is from oil; we use oil to cook things as well as flavoring for salads and more. Oils come in the “good” form and the “bad.” We are going to consider what part oils should play within a ketogenic diet and focus on their fatty-acid profile as well as their stability when heated.
It is important to separate fats and oils into two sections when looking at a ketogenic diet and weight loss: those with which we cook and those with which we add to food. It is far too easy to use a heap of butter when cooking, failing to precisely measure it and correctly include it within our caloric calculations. In addition, the glugs of olive oil that go onto the salad can soon mount up, and if losing weight is your goal, those extra calories from oils are not going to do you any favors. Despite the keto notion of “add fat to satiety,” these extra calories can limit your ability to burn the body’s fat stores.
We can use that same thought process when looking at which fats and oils are conducive to good health. Certain types of fat are more stable when heated than others. For example, saturated fats can withstand higher cooking temperatures than monounsaturated fats like olive oil and avocado oil. These monounsaturated fats (found within olive and avocado oils) are high in oleic acid (omega-9 fatty acids). This fatty acid is important because it has particularly been shown to be protective against metabolic syndrome and cardiovascular risk factors. [1]
Oils on keto supply large amounts of omega-3, omega-6 and omega-9 polyunsaturated fatty acids (PUFAs), and the balance of these fatty acids within the diet are of interest when looking at health and longevity. Omega-3 fatty acids, known for their positive effect on the brain, are most commonly found within oily fish, but they can also be found in walnuts, flaxseeds, pecans, sesame seeds, and more. Omega-6 fatty acids are found everywhere in the generic diet consumed by most people, where they are usually found within vegetable oils such as soybean oil, canola oil, and sunflower oil. A study on rats comparing iso-caloric diets (calorie matched), found soybean oil to be more obesogenic (causing obesity) and associated with higher incidence of fatty liver than coconut oil [2] ; considering soybean oil is found in so many food products, this is not good. Because of the sheer prevalence of these omega-6 fatty acids within our diets, it is necessary to focus on increasing omega-3 intake. Some groups suggest a ratio of 4:1 (omega-6:omega-3) and others suggest closer to 2:1. As long as you are sticking to a diet mainly comprised of real food that includes oily fish and seeds, you should not have a problem.
Popular within the ketogenic diet are medium-chain triglycerides (MCTs). Primarily found within coconut oil, MCTs are a particularly ketone-friendly fat. MCT fats are easily digested and sent directly to your liver to be rapidly used as fuel for the body’s cells. MCTs have far-reaching benefits including their ability to supply quick energy, anti-oxidant properties, and gut-supporting functions. Some people supplement their diet with MCTs while others get their MCTs through the daily use of coconut oil.
Fats and oils require a larger discussion than one article can cover. Above is an introduction to fats, and in later articles we will cover which fats you should cook with, add as a dressing, and supplement with (or not) as well as cover the negatives associated with oils in greater detail.
Gillingham, L. G., Harris‐Janz, S., & Jones, P. J. (2011). Dietary monounsaturated fatty acids are protective against metabolic syndrome and cardiovascular disease risk factors. Lipids, 46(3), 209-228.
Deol, P., Evans, J. R., Dhahbi, J., Chellappa, K., Han, D. S., Spindler, S., & Sladek, F. M. (2015). Soybean oil is more obesogenic and diabetogenic than coconut oil and fructose in mouse: potential role for the liver. PloS one, 10(7), e0132672.