The fat composition of a ketogenic diet has implications beyond its macronutrient ratio. Different fatty acids have distinct biological effects on inflammatory signalling, cardiovascular risk markers, and long-term health outcomes. On a conventional animal-fat-based ketogenic diet, the high saturated fat content from meat and dairy raises LDL cholesterol in a significant proportion of participants. On a plant-based ketogenic diet, the fatty acid composition can be actively optimised toward health-promoting fats while maintaining ketosis.
Monounsaturated Fat Sources
Extra-virgin olive oil and avocados are the highest-quality monounsaturated fat sources available. Oleic acid, the primary fatty acid in both, has documented cardiovascular protective effects, improves insulin sensitivity, and has anti-inflammatory properties when combined with the polyphenolic compounds present in extra-virgin olive oil. These should form the primary fat sources in a plant-based ketogenic diet. Avocado oil has a similar fatty acid profile with a higher smoke point and is appropriate for higher-temperature cooking.
Coconut Oil: A Nuanced View
Coconut oil is popular in ketogenic diets because its high medium-chain triglyceride content, particularly caprylic and capric acid, is rapidly converted to ketones and may enhance ketosis. However, the dominant fatty acid in coconut oil is lauric acid, a 12-carbon saturated fat that raises both LDL and HDL cholesterol. The cardiovascular consequences of this LDL elevation remain debated, but given the abundance of monounsaturated fat options with clearer health benefits, coconut oil is best used in moderate quantities specifically when its ketone-producing properties are desired, rather than as a primary fat source.
Nuts and Seeds
Nuts and seeds provide a combination of monounsaturated, polyunsaturated, and saturated fats alongside protein, fibre, and extensive micronutrients. Walnuts have the highest omega-3 ALA content and the strongest cardiovascular evidence base. Macadamia nuts are the highest in oleic acid and the lowest in polyunsaturated fats, making them the most shelf-stable and oxidation-resistant nut. Pecans and hazelnuts are rich in oleic acid. Brazil nuts provide selenium, a micronutrient commonly low in plant-based diets. Chia and flaxseeds provide ALA omega-3s and high fibre.
MCT Oil
MCT oil, fractionated coconut oil containing primarily C8 and C10 medium-chain triglycerides, rapidly produces ketones and can help maintain ketosis even with slightly higher carbohydrate intake. It is useful for people transitioning to plant-based keto, for athletes who need to fuel performance while maintaining ketosis, and for people finding ketosis difficult to achieve with whole-food fat sources alone. The appropriate dose is typically 10 to 30ml per day, starting at the lower end to avoid the gastrointestinal symptoms that MCT oil commonly produces at higher doses in people not yet adapted to it.