Quick answer: MCT oil contains medium-chain fats that are absorbed quickly and converted into ketones, which can make ketosis easier. Because keto limits fruits, grains and legumes, pay attention to magnesium, potassium and B vitamins by eating plenty of leafy greens, avocado, nuts, seeds and quality protein. Research also suggests ketones may support mitochondrial function.
Key takeaways
MCTs are medium-chain fats that go straight to the liver, where they are burned for energy or turned into ketones.
MCT oil is best started in small amounts, since it can upset the stomach, and it is still a concentrated source of calories.
Magnesium, potassium and other micronutrients need attention on keto, and ketones may also serve as an efficient fuel for mitochondria.
What are MCTs?
Medium-chain triglycerides have fatty acids 6 to 12 carbons long. Unlike long-chain fats, they go straight to the liver, where they are burned for energy or turned into ketones. Coconut oil is a natural source.
Using MCT oil
Start with small amounts and increase slowly, since MCT oil can cause stomach upset and diarrhea. It is still a concentrated source of calories. Discuss the amount with your provider.
Micronutrients that need attention
- Magnesium: muscle and nerve function, heart rhythm (leafy greens, nuts, seeds)
- Potassium: fluid balance and muscle function (avocado, leafy greens, salmon). See balancing electrolytes
- B vitamins: energy production and brain function (meat, eggs, fish)
Keto and mitochondria
Ketones as fuel
Beta-hydroxybutyrate is an efficient fuel for mitochondria.
Lower oxidative stress
Lower blood sugar may reduce reactive oxygen species that damage mitochondria.
Mitochondrial biogenesis
Animal research suggests keto may encourage new mitochondria to form.
Nutrients for ATP production
ATP production relies on magnesium, B vitamins, zinc and vitamin C, along with calcium, copper, chromium and manganese.
Healthy aging lens
Mitochondrial function declines with age. Movement, sleep and a nutrient-dense diet support it. See mitochondrial health.
What the research shows
MCT oil is one of the better-studied keto-friendly fats.
MCTs across 13 trials (Mumme 2015, meta-analysis). This review pooled 13 randomized trials with 749 adults that replaced regular long-chain fats with medium-chain triglycerides. MCTs were linked with about 0.5 kg more weight loss and about 1.5 cm less waist size, with no change in blood lipids. The authors noted that many trials were poorly reported and some showed signs of commercial bias, so the effect, while consistent, is modest.
MCT oil vs. olive oil (St-Onge 2008, randomized trial). 49 adults with overweight used 18 to 24 g a day of either MCT oil or olive oil as part of a 16-week weight-loss program. Among the 31 who finished, the MCT group ended about 1.7 kg lighter than the olive oil group and had less trunk and abdominal fat. A limitation is the high dropout rate (18 of 49 did not finish) and the small size.
Six weeks of keto in healthy adults (Urbain 2017, before-and-after study). 42 healthy adults followed a ketogenic diet (about 72% fat, 21% protein and 8% carbohydrate) without calorie limits for 6 weeks. They lost about 2 kg, split equally between fat and lean mass. Peak power dropped 4%, LDL cholesterol rose about 11%, and insulin fell 22%. A limitation is that there was no control group, so changes can’t be fully separated from other factors.
Strength of the evidence: MCT oil has small but consistent effects; keto may also lower intake of fiber-rich plants, so planning for micronutrients matters.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have diabetes or take insulin, sulfonylureas or SGLT2 inhibitors (risk of low blood sugar or ketoacidosis), or if you take blood pressure medication or diuretics. The same is true if you have kidney, liver, gallbladder or pancreas disease, or high cholesterol, if you are pregnant, breastfeeding, or have a history of disordered eating, or if you want a keto plan tailored to your labs and goals.
See a medical provider promptly for nausea and vomiting, abdominal pain, confusion, fruity-smelling breath with rapid breathing, or very high blood sugar or ketone readings, which can signal ketoacidosis.
Want a keto plan that’s safe for your health?
A free 15-minute consultation with Dr. Kneessi. No cost, no obligation. In-office in Odenton, MD or by telehealth.
Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Would MCT oil be appropriate for me, or could it bother my digestion or cholesterol?
Could MCT oil alongside a ketogenic diet interact with any of my current medications or other supplements?
Would any labs or health history details help us decide whether MCT oil alongside a ketogenic diet makes sense for me?
How would we tell whether MCT oil alongside a ketogenic diet is a good fit for me, and when should we check in again?
Frequently asked questions
What is MCT oil good for on keto?
It is quickly turned into ketones, which can help with ketosis.
Does MCT oil have side effects?
It can cause digestive upset, especially in larger amounts.
Which nutrients can run low on keto?
Magnesium, potassium and B vitamins are common concerns.
Does keto help mitochondria?
Early research suggests it may.
Sources
- St-Pierre V, et al. Plasma Ketone and Medium Chain Fatty Acid Response in Humans Consuming Different Medium Chain Triglycerides During a Metabolic Study Day. Front Nutr 2019. PMID: 31058159. https://pmc.ncbi.nlm.nih.gov/articles/PMC6481320/
- Schönfeld P, Wojtczak L. Short- and medium-chain fatty acids in energy metabolism: the cellular perspective. J Lipid Res 2016. PMID: 27080715. https://pmc.ncbi.nlm.nih.gov/articles/PMC4878196/
- de Baaij JH, Hoenderop JG, Bindels RJ. Magnesium in man: implications for health and disease. Physiol Rev 2015. PMID: 25540137. https://pubmed.ncbi.nlm.nih.gov/25540137/
- Bough KJ, et al. Mitochondrial biogenesis in the anticonvulsant mechanism of the ketogenic diet. Ann Neurol 2006. PMID: 16807920. https://pubmed.ncbi.nlm.nih.gov/16807920/
- Sun N, Youle RJ, Finkel T. The Mitochondrial Basis of Aging. Mol Cell 2016. PMID: 26942670. https://pmc.ncbi.nlm.nih.gov/articles/PMC4779179/
- NIH ODS: Magnesium
- MedlinePlus: Dietary Fats
- Mumme K, Stonehouse W. Effects of medium-chain triglycerides on weight loss and body composition: a meta-analysis of randomized controlled trials. J Acad Nutr Diet 2015. PMID: 25636220. https://pubmed.ncbi.nlm.nih.gov/25636220/
- St-Onge MP, Bosarge A. Weight-loss diet that includes consumption of medium-chain triacylglycerol oil leads to a greater rate of weight and fat mass loss than does olive oil. Am J Clin Nutr 2008. PMID: 18326600. https://pubmed.ncbi.nlm.nih.gov/18326600/
- Urbain P, et al. Impact of a 6-week non-energy-restricted ketogenic diet on physical fitness, body composition and biochemical parameters in healthy adults. Nutr Metab (Lond) 2017. PMID: 28239404. https://pubmed.ncbi.nlm.nih.gov/28239404/
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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