If you’re an athlete or fitness enthusiast, you know that nutrition plays a huge role in exercise performance. The foods we eat provide the raw materials that power our workouts. In particular, dietary fats are an important energy source for prolonged exercise. But not all fats are created equal when it comes to fueling exercise. Emerging research suggests that a type of fat known as medium chain triglycerides (MCTs) could give your workout an extra boost.
What Are MCTs and Where Are They Found?
MCTs are a form of saturated fat with unique properties. Most dietary fats contain 12-18 carbon atoms per molecule and are known as long chain triglycerides (LCTs). In contrast, MCTs contain only 6-10 carbon atoms per molecule, making them shorter and smaller. This difference in chemical structure gives MCTs unique characteristics.
The most common sources of MCTs are coconut and palm kernel oils. Compared to other vegetable oils, coconut oil contains the highest amount of MCTs – around 65%. MCT oil supplements containing concentrated amounts of MCTs are also available. MCTs comprise about 15-30% of mother’s milk, which is thought to contribute to faster growth and development in breastfed infants compared to formula-fed infants.
Why MCTs Could Boost Exercise Performance
Compared to LCTs, MCTs are more rapidly absorbed and metabolized. They go straight from the gut to the liver, where they are readily burned for energy. In contrast, LCTs require bile salts and transport mechanisms to be broken down and absorbed by the body.
Once in the liver, MCTs don’t require carnitine transport to enter mitochondria like LCTs. This means they can quickly enter the cellular energy producing pathways. The result is that MCTs are preferentially used as fuel during exercise rather than being stored as body fat.
Research in both humans and animals demonstrates that MCTs increase energy expenditure, fat burning, and oxygen consumption compared to LCTs. This suggests that replacing some dietary LCTs with MCTs could potentially enhance exercise capacity and endurance. Let’s explore some of the studies on MCTs and exercise performance.
MCT Study #1: Mice Run Farther and Longer
Researchers wanted to see if an MCT-containing diet could prevent the decreased exercise capacity that occurs in hot environments. Mice were fed either a normal diet or a diet containing 11.6g/kg of MCTs for 7 days. The mice then went through a 14 day exercise training protocol on a treadmill either at room temperature or in a heated chamber.
On day 15, the mice ran on a treadmill until exhaustion. Their endurance capacity was tested using a rotating rod device. Mice fed the MCT diet were able to run for over twice as long as the mice fed the normal diet when exercising in heated conditions! The researchers concluded that dietary MCTs can improve high temperature induced decreases in exercise performance.
MCT Study #2: Combining MCTs, Leucine, and Vitamin D for Muscle Strength
Researchers did a 3 month trial in frail elderly adults comparing a control group to a group taking a supplement containing MCTs, the amino acid leucine, and vitamin D. They found that the combination supplement increased grip strength and walking speed compared to the control. While MCTs alone weren’t tested, this study suggests they may play a role in boosting muscle function.
MCT Study #3: No Effect on Endurance Exercise
Not all studies on MCTs and exercise have been positive. One analysis reviewed several studies comparing diets containing MCTs versus LCTs. They concluded that MCTs don’t enhance endurance exercise capacity or performance under normal conditions in trained individuals. However, none of these studies looked at exercise under stressful hot environments.
How Could MCTs Improve Exercise Performance and Endurance?
The potential beneficial effects of MCTs on exercise don’t appear to be due to influencing metabolism during the workout itself. Instead, studies suggest that supplementing with MCTs induces adaptations like increased mitochondrial biogenesis and enhanced fat burning capability over time. Let’s take a look at some of the proposed mechanisms:
- Increased mitochondrial biogenesis – Mitochondria are the cell’s powerhouses where fat and carbohydrates are burned for energy. MCT supplementation has been shown to increase mitochondrial mass and activity in skeletal muscles. This adaptation could allow more oxygen consumption and greater fat burning.
- Activation of key metabolic signaling pathways – MCT intake activates Akt and AMPK, two important signaling molecules that trigger increases in fat and glucose metabolism. Activating these pathways could potentially increase the muscles’ ability to use fat during exercise.
- Inhibition of TGF-beta signaling – TGF-beta is a molecule that impairs mitochondrial function and suppresses metabolism. MCT supplementation lowers levels of the downstream mediator Smad3, potentially reversing these detrimental effects of TGF-beta on muscle endurance.
- Increased insulin sensitivity – Along with activating Akt, MCT supplementation improves insulin sensitivity. This could allow the muscle to use sugars more efficiently and take up blood glucose at higher rates during exercise.
The increase in mitochondrial biogenesis and fat burning capacity induced by MCTs takes time – likely at least 1-2 weeks. This could explain why studies examining immediate exercise performance after a single dose of MCTs show little benefit. The adaptations happen behind the scenes.
Should You Supplement with MCT Oil?
MCT oil supplements containing concentrated amounts of MCTs are popular among athletes and fitness enthusiasts. MCT oil provides 50-80% more MCTs than coconut oil and is flavorless and odorless. It’s gaining popularity in smoothies, sauces, salad dressings, and coffee drinks.
Replacing some LCTs with MCT oils could provide better fuel for your workouts. The average Western diet contains a large excess of LCTs from vegetable oils, nuts, meat, dairy etc. Substituting around 20% of dietary fat with MCT oils could potentially induce mitochondrial and metabolic adaptations to enhance endurance.
However, keep in mind that MCT oil provides pure calories with no vitamins, minerals, or phytonutrients. Consuming large amounts can lead to excessive calorie intake. Here are some tips for including MCT oil strategically:
- Use MCT oil to replace other oils in your diet rather than adding on top of them
- Limit MCT oil to 1-2 servings per day (1 tablespoon is 120 calories)
- Be cautious if trying a ketogenic diet with very high MCT intake – start with smaller amounts
- Consider a powdered MCT oil that mixes easily into drinks rather than liquid oil
- Purchase high quality MCT oil and store away from heat and light after opening
The optimal amount of MCT oil likely depends on the individual. It’s best to start low (1 tsp per day) and slowly increase intake while assessing exercise performance and recovery. Avoid taking large amounts right before intense exercise since digestive distress could occur.
MCTs don’t appear to be a magic bullet for exercise, but they could provide an edge through their unique metabolic effects. If you’re looking to maximize your gym performance and push your endurance to the next level, MCTs are worth a try!
