L-carnitine is a popular supplement among athletes and those seeking to manage their weight. It's often touted for its fat-burning capabilities and potential to enhance exercise performance. But with so much information available, it can be difficult to separate fact from fiction. This article will explore what L-carnitine is, its benefits, how it works, the different types, optimal dosages, food sources, potential side effects, and, most importantly, the best time to take it for weight loss.
What is L-Carnitine?
L-carnitine is a non-essential amino-acid-like compound, meaning that the body produces it naturally. It plays a vital role in energy production by transporting long-chain fatty acids into the mitochondria of cells, where they are oxidized to produce energy. More than 95% of the body's L-carnitine is stored in skeletal muscle, with trace amounts in the liver and blood.
While the body produces L-carnitine, it can also be obtained through diet, primarily from red meat. Plant sources like avocado and soybean contain smaller amounts. Supplements can be beneficial for those who struggle to get enough L-carnitine through diet alone.
Benefits of L-Carnitine
Weight Loss
One of the primary reasons people use L-carnitine is for weight loss. L-carnitine may aid weight loss by allowing you to train for longer and increase your calorie expenditure. It has been theorized that L-carnitine could help the body produce energy by utilizing the body’s fat stores, allowing you to work out for longer and ultimately aiding in fat loss. Evidence suggests it may promote weight loss by increasing calorie expenditure. Taking an L-Carnitine supplement daily has been proven to increase the blood and muscular concentrations of this amino acid-like compound, which could enhance fat metabolism as a result with increased muscle carnitine concentrations.
Improved Exercise Performance and Recovery
L-carnitine optimises how your body uses fat for fuel, allowing you to exercise for longer. Supplementing with L-carnitine could also play an important role in recovery from strenuous exercise, with suggested doses of 2-4g daily to optimise results. There’s initial evidence that this could lead to a reduction in various markers of metabolic stress and muscle soreness which is replicated in many studies. However, research is still limited and further studies are needed. Some research has also found that three weeks’ supplementation with an L-carnitine supplement reduces muscle damage from high intensity exercise bouts.
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Support for Heart Health
L-carnitine may boost energy levels as it increases the amount of fuel availability that the heart requires to function. Research supports medically supervised use of L-carnitine for treating cardiac related issues and is often given by IV by a medical professional. L-carnitine may also play a role in keeping cholesterol levels in a healthy range. In a systematic review by the Mayo Clinic, carnitine was associated with a 27% reduction in all-cause mortality.
How L-Carnitine Works
L-carnitine enhances the transportation of long-chain fatty acids into the mitochondria of the muscle cells and increasing fuel availability during low-moderate intensity exercise. When you exercise, thousands of biochemical reactions are taking place inside your body. One of these is the action of your enzymes starting to break down stored fat into fatty acids and glycerol, a sugar alcohol. These are then used as fuel throughout exercise. Studies have theorized that L-carnitine is a compound that plays an important role in this process of fat metabolism as its key role is to transport the long-chain fatty acids across the inner membrane. These fatty acids are thought to be the main energy sources used during low- to moderate intensity exercise.
Types of L-Carnitine and Their Uses
The two main variations of L-carnitine that are supplemented in the diet are L-carnitine tartrate and acetyl L-carnitine.
L-Carnitine Tartrate
L-carnitine tartrate has a rapid absorption rate and helps with fatty acid metabolism. L-carnitine tartrate is one of the most common forms of L-carnitine found in sports nutrition supplements due to its rapid absorption rate. It’s created in the body from the amino acids lysine and methionine and is mainly synthesized in the liver and kidneys before being transported for use in other tissues in the body. L-carnitine tartrate is found in its highest levels in tissues that use fatty acids as the main fuel source, such as the skeletal and cardiac muscles. It should be taken in conjunction with a healthy, balanced diet and exercise regime.
Acetyl L-Carnitine (ALCAR)
Acetyl L-carnitine has an acetyl group attached to the carnitine making it more bioavailable and easier to absorb. ALCAR has an acetyl group attached to the carnitine molecule. This allows it to pass through the blood-brain barrier making it the most bio-available, and thus most easily absorbed, form. ALCAR is ideal for athletes and active people who take part in regular exercise or anyone looking for an easy-to-consume source of L-carnitine that can be taken throughout the day. Acetyl L-carnitine is created in the body from the amino acids’ lysine and methionine.
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Dosage
Studies suggest varying doses for each form of L-carnitine for best results, the following is deemed optimal for each form of carnitine:
- Acetyl-L-Carnitine: 600-2,500 mg per day.
- L-Carnitine L-Tartrate: 1,000-4,000 mg per day.
- Propionyl-L-Carnitine: 1,000-4,000 mg per day.
A usual carnitine dose is between 500mg and 2g per day, and this is sufficient to aid fat burning, promote endurance, enhance recovery and benefit from the ergogenic effects of this amino acid. It may be taken in it form of powder or capsule and drunk with water.
Best Time to Take L-Carnitine for Weight Loss
The best time to take L-carnitine can depend on the individual and their specific goals. However, for optimizing energy during your workout, it’s best to take it prior to working out. Most scientific studies recommend taking L-carnitine about one hour prior to exercise. However, if you want to take advantage of the other benefits (recovery and weight loss support), taking it after exercise can also be effective.
Here are a few general guidelines for when to take L-carnitine:
- Before exercise: Taking L-carnitine before exercise can help to increase energy levels, endurance, and fat burning during a workout. Intake of L-carnitine 60-90 minutes before exercise will allow your body to digest the supplement and benefit from improved energy production when you need it.
- After Exercise: Some users take L-Carnitine afterwards to enhance their recovery. Research has shown that post-workout L-carnitine supplementation can reduce muscle soreness and reduce markers of muscle damage when taken post-workout.
- With Carbohydrates: Consuming L-Carnitine with carbohydrates may improve its uptake and increase insulin levels, which in turn helps in transporting L-Carnitine into muscle cells. The ingestion of fast-digesting carbohydrates will facilitate an insulin spike and can maximize the transport of L-carnitine to your muscle cells. An insulin spike from carbohydrates may improve the transport of L-carnitine to the muscles.
- In the morning fasted: Some people like to take L-carnitine in the morning, in a fasted state, then combine this with exercise. Users who do this believe the combination of L-carnitine supplementation, being fasted and working out accelerates fat loss goals.
- Before bedtime: Taking L-carnitine before bedtime can help to support fat burning and muscle recovery during sleep. Many users we have seen over the years use this strategy.
A good compromise is to split the desired dose into two and take half before and a half after training, making sure to pair it with a source of carbohydrates. Because L-carnitine accumulates in muscle, it is fine to take at any time of day, and because of the carbohydrate requirement for absorption, it is best taken with a main meal.
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L-Carnitine & Carbohydrates
Uptake is a very important consideration with carnitine, and a lot of research has shown that it is best absorbed when it is taken together with a large dose of carbs, 60-80g. Carbohydrates in general stimulate the release of insulin, which can help to increase the uptake of amino acids, including L-carnitine, into the muscle cells. This in turn may enhance Lcarnitines benefits.
Which foods contain L-carnitine
Although this supplement can be made by the body, you can also up your L-Carnitine intake from your diet. It’s highest in animal products like beef, lamb, pork, poultry, fish, and dairy products. Whey (made from milk) naturally contains some L-carnitine, and plant-based sources contain it in small amounts, like nuts, seeds, whole grains and some fruits and vegetables (like avocados and asparagus).
L-Carnitine Side Effects
Side effects of this supplement are mild because it’s naturally found in our food. Following dosage recommendations did not show serious adverse side effects when taken for less than 12 months, but included stomach upset, breath and urine odor, and seizures in some cases. Consult a GP if you’re considering L-carnitine.
How Long to Take L-Carnitine
Oral carnitine has been shown to increase the levels of muscle carnitine, but some studies have shown that meaningful increases can take up to six months to occur. People commencing L-carnitine supplementation should commit to at least six months of use and evaluate effectiveness after this time.
Should I Cycle L-Carnitine
It is not necessary to cycle carnitine. There is no scientific evidence that suggests cycling L-carnitine is necessary. However, some people do choose to cycle L-carnitine as a way to maximize what they believe is its effectiveness, there is however little science to support this theory. Carnitine comes as a powder that mixes easily into most beverages, or as an easily swallowed capsule.
L-carnitine for Vegans and Vegetarians
L-carnitine is a common form of carnitine, an amino acid found in animal products, especially red meat. L-carnitine levels are often lower in vegetarians and vegans since they restrict or avoid animal products.
Therefore, vegetarians and vegans may want to consider L-carnitine supplements, which can help normalize carnitine levels in the blood and muscles.
Precautions
According to the NIH, several drugs have the potential to interact with L-carnitine. People who are taking certain types of antibiotics and anticonvulsants should speak with a doctor before taking L-carnitine, as this supplement may interact with the medications.
Conclusion
L-Carnitine is a versatile supplement with numerous benefits for energy production, fat burning, endurance, recovery, & muscle growth. To maximize its effectiveness, it is recommended to take L-Carnitine in a dose of 500mg to 2g per day, preferably in the form of powder or capsules mixed with water. Pairing L-Carnitine with a carbohydrate-rich meal or consuming it before a workout can enhance its absorption & promote energy levels & fat loss. Long-term supplementation for at least six months is advised to experience the full benefits of L-Carnitine. While there is no scientific evidence supporting the need for cycling L-Carnitine, some individuals choose to do so. The best time to take L-Carnitine varies based on personal goals, but options include before exercise, after exercise, in the morning while fasting, with meals, or before bedtime. Ultimately, understanding individual preferences and experimenting with different timings may help optimize the use of L-Carnitine for specific fitness goals.
While there are some positive results with L-carnitine supplementation, it must be considered that the overall scientific evidence is lacking. The various forms of L-carnitine are perfect supplements for people who don’t easily acquire it from natural food sources as a part of their normal diet.
FAQs
When is the best time to take L-carnitine?
It is recommended to take this supplement with fast acting carbohydrates. Whether it is taken pre or post workout isn’t considered an important factor.
What is L-carnitine?
This supplement is a non-essential amino-acid-like compound, responsible for transporting long-chain fatty acids to your cell’s mitochondria, where energy is produced from the fat’s oxidization.
What are the benefits of L-carnitine?
Evidence suggests that this supplement may promote fat loss and optimize exercise performance and recovery.
How does L-carnitine work?
This supplement transports fatty acids across the inner membrane. These fatty acids are thought to be the main energy source during low to medium intensity exercise.