MCT Oil: What It Does and What It Doesn’t
The ketogenic diet relies on fats for fuel, and medium-chain triglyceride (MCT) oil has become a staple supplement for many following this approach. Unlike long-chain fats found in most foods, MCTs are rapidly absorbed and converted into ketones by the liver. This makes them particularly useful during the keto adaptation timeline, when the body is still learning to burn fat efficiently.
How MCT Oil Works
MCT oil contains fatty acids with 6 to 12 carbon chains, primarily caprylic (C8) and capric (C10) acids. These bypass normal fat digestion, going straight to the liver where they’re oxidised into ketone bodies. A 2013 review in the European Journal of Clinical Nutrition noted that MCTs increase ketone production more effectively than other fats, which may help bridge energy gaps during carbohydrate restriction.
What MCT Oil Actually Does
1. May support ketosis: Studies like those by Volek and Phinney (2008) show MCTs can elevate blood ketone levels by 2-3x compared to other fats, useful for those struggling to reach nutritional ketosis. 2. Provides rapid energy: Unlike olive oil or butter, MCTs don’t require bile for breakdown. They’re absorbed within minutes, making them ideal pre-workout for keto athletes. 3. Could aid cognitive function: Some research suggests the ketones from MCTs cross the blood-brain barrier, potentially offering mental clarity. Waitrose now stocks brain-boosting keto coffee blends with MCT oil for £7.99 per 250ml bottle.
What MCT Oil Doesn’t Do
Despite marketing claims, MCT oil:
- Doesn’t ‘burn fat’ directly – any weight loss comes from calorie deficit, not the oil itself.
- Isn’t essential for ketosis – many achieve it through whole foods alone.
- Doesn’t replace electrolytes – newcomers often mistake MCT energy for common keto electrolyte mistakes.
What This Means in Practice
For UK keto followers, MCT oil is widely available at Tesco (£12 for 500ml) and Holland & Barrett. During colder months, adding it to bulletproof tea can help maintain energy when seasonal cravings hit. The NHS doesn’t regulate MCT supplements, so opt for brands listing at least 50% C8 content for maximum ketogenic effect.
Frequently Asked Questions
Is MCT oil better than coconut oil?
Coconut oil contains about 15% MCTs naturally, while purified MCT oil is 100% medium-chain triglycerides. For targeted ketone elevation, MCT oil is more effective. For cooking, coconut oil remains practical.
Can MCT oil cause digestive issues?
Yes. Starting with 1 tsp daily prevents the diarrhoea some experience when consuming large amounts abruptly. The gut adapts over 2-3 weeks.
Should I take MCT oil every day?
Not necessarily. Those fully fat-adapted often use it situationally, like before fasted exercise or high-focus work sessions. Daily use isn’t harmful but isn’t mandatory.
The Bottom Line
MCT oil serves specific purposes in a ketogenic diet—primarily boosting ketones and providing quick energy. It’s not a weight loss hack or ketosis requirement. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.
References
- Paoli A, Rubini A, Volek JS, Grimaldi KA (2013). Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition. https://doi.org/10.1038/ejcn.2013.116
- Volek JS, Phinney SD, Forsythe CE, et al. (2008). Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids. https://doi.org/10.1007/s11745-008-3274-2
