Want the perfect workout program?Take Quiz
Fact checked by Andrew Lenau, ISSA CPT & Sports NutritionistFACT CHECKED
June 21, 2023
Do you ever feel overwhelmed trying to find the perfect weight loss supplement? Or even worse, have you wasted money on some "miracle pill" that claimed it would help burn fat but gave you nothing but side effects?
Don't fall for the false claims and bogus products. Instead, let science-based research guide you toward the best weight loss products.
Enter L-carnitine, a naturally occurring amino acid produced in the body that helps us turn fat into energy.
So what does science say about L-carnitine for weight loss? In this article, we will explore the research to discover everything regarding L-carnitine, including finding the best L-carnitine for weight loss.
Table of Contents:
L-carnitine is a chemical, referred to as a quaternary ammonium cation compound, that plays a significant role in metabolism and other important bodily functions.
L-carnitine is a naturally occurring derivative of one of the amino acids, lysine, that's produced in the brain, kidneys, and liver but stored in the muscles. While you can get L-carnitine in certain foods, many supplement it for added benefits. The primary role of L-carnitine is to transport fatty acids into cells' mitochondria, which results in energy production.
To keep it simple, L-carnitine encourages fatty acid oxidation, so we can use fat to create energy. It also has other minor bodily roles, like supporting healthy brain function and muscle movement.
As if finding the perfect supplement for weight loss wasn't hard enough, you also have to distinguish between different types. This section will break down the different types and find the best L-carnitine to lose weight.
Acetyl L-carnitine, or ALCAR, is most commonly used to improve cognitive function and support brain health. It's one of the two most commonly used types, along with carnitine L-Tartrate, which is typically the preferred L carnitine for weight loss. You can read more about this in our article: Is L Carnitine Good For Weight Loss?
Acetyl L-carnitine, however, is absorbed the fastest and can also be used for fat loss. People with a healthy diet typically get between 20-135 milligrams of L-carnitine a day from foods. However, it comes from animal-derived products, so vegetarians and vegans could potentially be getting zero milligrams.
The best foods to eat to get acetyl L-carnitine naturally include:
Other foods that contain small amounts of less than 1 mg per serving include asparagus and whole wheat bread, which are especially important for vegans and vegetarians1.
One of the less conventional ways of taking L-carnitine for weight loss, l-carnitine injections are used to lose weight, increase energy, improve athletic performance, and sometimes in male fertility treatments.
With injections, the typical L-carnitine dosage for weight loss is between two and six grams, taken daily for up to one month. A medical professional typically does L-carnitine injections intravenously, but they also sell home kits that can be injected intramuscularly, usually in the front thigh region.
While injections are typically reserved for those with deficiencies or medical issues like kidney disease, some prefer them due to the higher absorption rate. L-carnitine injections allow amino acids to enter the bloodstream directly and enhance lipid metabolism faster than oral doses.
Injections have a 90-99% absorption rate, whereas oral supplements are much lower. Studies have found that oral bioavailability is only around 14-18%, compared to 54-87% dietary absorption2. This extremely high absorption rate makes the injections popular, but they are not for everyone.
Many people prefer not to use needles, as they can be scary and not taken as easily. Oral supplements are much easier to use, less expensive, and more readily available, making them a more popular choice.
While the list of benefits is long, most gym-goers turn to L-carnitine supplements to boost energy to help support protein synthesis for muscle growth and weight loss.
L-carnitine supplements most commonly come in pill form, with the typical dose or serving size of 500 milligrams. You can also get them in tablet, powder, and liquid form, including single-serving ready-to-drink bottles. At the end of the day, it comes down to personal preference, as some people like tablets while others prefer to add powder to shakes.
My favorite option readily available on Amazon is NOW L-Carnitine. NOW Supplements is one of the leading brands in the industry, offering high-quality products at affordable prices. A 60-count bottle is only $13, which is a one-month supply at 1,000 mg daily.
Most products are around 500 mg, as the best L-carnitine dose for weight loss is between 1,000-2,000 mg daily. While several different types of supplements contain L-carnitine, many people turn to convenient standalone products to support overall health at an affordable rate.
While standalone products are great for overall health, people looking to lose weight by burning fat should consider a fat burner supplement that contains L-carnitine.
One of the best all-natural fat burners containing L-carnitine is Kaged Muscle Clean Burn. Kaged is widely regarded as one of the top fat burners on the market and is my favorite for natural products. It's a non-stimulant and contains only five ingredients, including 1,000 mg of L-carnitine L-Tartrate.
This particular L-carnitine is a patented version called Carnipure, which is the highest grade and backed by research, making it widely used in supplements. Kaged also contains green tea extract, chromium, Gymnema sylvestre leaf extract, and Capsimax, a thermogenic derived from red chili pepper extract.
My second favorite option is Transparent Labs Stim-Free. While this product is similar in that it is all-natural and stimulant-free, it is slightly different in that it uses 750 mg of acetyl L-carnitine per serving.
Acetyl L-carnitine is the fastest absorbed of any type, so it's useful around a workout to repair muscles, improve energy, and increase endurance rapidly. So although the dosage is slightly less than the 1,000 mg in Kaged, it works quickly in combination with the other ingredients to fuel weight loss.
Transparent Labs also contains a wide range of popular fat-burning ingredients such as green tea leaf extract, Capsimax, Cayenne pepper, 5-HTP, and vitamin B12, among others.
L-carnitine targets fat loss, starting with transporting long-chain fatty acids into cell mitochondria, where they are oxidized. Once it enters the mitochondria, it breaks down the fat stored for energy use. Simply put, L-carnitine helps convert stored fat into usable energy, resulting in fat loss.
A scientific review of nine studies found that participants using L-carnitine lost an average of 2.9 pounds more than the control and had a decrease in body mass index3.
It also helps with weight loss because of its ability to increase energy, improve physical performance, and improve workout recovery. These benefits allow the body to work out efficiently and maintain lean muscle mass, which in turn helps burn fat faster.
While l carnitine supplements can certainly assist anyone on a weight loss journey, there are a few other things to consider.
If you ask people how to lose weight, the most common answer is exercising regularly or dieting. While this is a vague generalization, both are highly successful fat-burning strategies.
An overview of 12 systematic reviews featuring 149 studies concluded that exercise programs led to significant weight loss, fat loss, and visceral fat loss4. You have to be at a caloric deficit to lose weight, which means you need a way to burn calories. The method of exercise or cardio is your choice, such as walking, running, or playing sports, as long as it burns calories and is done consistently.
If you are anything like me, you avoid cardio as much as possible. Luckily, weight training is one of the best ways to lose weight.
One study sought the effects of resistance training on fat loss compared to aerobic training and a combination of both. Lean body mass significantly increased in the resistance and combination training groups but not in the aerobic training group.
While the results showed a more significant loss in body weight and fat mass in the aerobic group compared to just resistance training, they found a combination of both to be the best method to lower body fat percentage5.
These results confirm the general idea among gym-goers that a combination of lifting weights and cardio is the most effective way to burn fat. Find a good workout split and stick to it!
To burn fat and lose weight, your body has to be at a caloric deficit, burning more calories throughout the day than you take in. While exercise is essential to burn calories, your diet is arguably more important.
A recent study from the Journal of the American Heart Association found that counting calories and eating less is more effective at fat loss than time-restricted eating, such as intermittent fasting6. Following a meal plan and meal-prepping is a great way to count calories and ensure your macronutrient breakdown is conducive to fat loss.
The most common macro breakdown for overall health and body composition is 40% carbohydrates, 30% protein, and 30% fat. Your exact macro breakdown will depend on your diet plan, as there are low-carbohydrate and high-fat diets. If you're looking for an effective way to shed pounds, check out our meal plan for weight loss.
While we've been focusing on the weight loss aspect of L-carnitine, there are several other benefits.
One of the most desired benefits of L-carnitine for athletes and gym-goers is its ability to increase athletic performance.
L-carnitine can improve athletic performance in multiple ways, including boosting energy, promoting fat oxidation, and preserving muscle glycogen. A systematic review from 2018 examined 11 different trials that tested L-carnitine for exercise performance and recovery.
Results showed that L-carnitine supplementation reduced lactate levels and heart rate with increased lipid metabolism, VO2 max, oxygen consumption, and improved performance7. These results also show our next benefit: reduced muscle soreness.
As we just touched on, one of the benefits of L-carnitine is reduced muscle soreness and improved recovery.
L-carnitine attacks muscle soreness in multiple ways, including by increasing blood flow and oxygen supply to muscle tissue. It also helps your body use fat for energy, which helps preserve stored muscle glycogen, therefore helping to prevent soreness.
One study tested how L-carnitine supplementation helps with recovery after exercise. The results showed that L-carnitine supplementation significantly improved muscle soreness at 0, 24, 48, 72, and 96 hours compared to a placebo8.
These results show that L-carnitine supplementation helps with muscle soreness immediately following a workout and up to five days later.
One non-exercise benefit of L-carnitine is its ability to reduce high blood pressure. Since one of the primary functions of L-carnitine is lipid metabolism, and effective lipid metabolism can help lower insulin resistance, its supplementation can lead to a reduction in blood pressure.
A meta-analysis of ten trials confirmed this when the results showed reduced diastolic blood pressure without changing systolic blood pressure9. In addition to helping lower blood pressure, L-carnitine has also been shown to help improve heart health and help prevent cardiovascular disease.
As we mentioned above, with muscle soreness, L-carnitine helps increase blood flow in certain areas.
One study examined the effects of injections versus oral dose and control in rats with ischemic skin flaps. Ischemic refers to reduced blood flow to an area of the body, and L-carnitine is often used for ischemic conditions like heart disease.
The results showed survival rates of 65.89% for the control, 69.03% for oral L-carnitine, and 77.47% for L-carnitine injections, suggesting that L-carnitine can be used to treat other blood flow issues10.
The rule of thumb to avoid side effects is to keep the dosage under three grams a day maximum. The most common side effects include abdominal cramps, nausea, diarrhea, vomiting, and a fishy body odor.
Long-term use may also produce mild side effects such as heartburn and indigestion. There are more serious potential side effects for those with existing medical conditions, including seizures for those with seizure disorders and muscle weakness for those with uremia. There's also a risk for severe allergic reactions, especially with certain medications like blood thinners or antibiotics.
L-carnitine is perfectly safe for pregnant women and is recommended for those with an L-carnitine deficiency. Its ability to break down fats and remove waste may help your baby's health if you don't take too high a dose. As always, it's best to speak to your doctor before starting any supplement.
The ideal L-carnitine dosage for weight loss is around 2 grams per day.
If you follow a strict diet, try adding chicken, steak, avocados, and other healthy foods containing L-carnitine to maximize weight loss efforts. These foods should be considered an added bonus, as the majority of your L-carnitine will come from supplements.
It's much easier to accurately track your daily intake with a supplement rather than rely on food, and l-carnitine supplements are a safer and more convenient alternative to injections. Like cancer patients, people who use L-carnitine medically are usually on a lower dose, between 250 milligrams to 3 grams a day.
There are mixed opinions regarding when to take L-carnitine, and no conclusive studies.
One school of thought is that it should be taken on an empty stomach first thing in the morning. The idea is that the body will absorb it much faster on an empty stomach, providing energy for the day.
A second opinion suggests taking L-carnitine pre-workout to maximize workouts and fat loss, particularly acetyl L-carnitine, due to its rapid absorption. Taking it pre-workout can boost energy and help improve performance by reducing lactic acid.
Lastly, it is recommended to take L-carnitine L-tartrate post-workout for its ability to help fight soreness and improve muscle recovery. If you use L-carnitine L-tartrate, you will need a higher dose, somewhere between 2-4 grams. This is more for people seeking improved performance and muscle recovery rather than those trying to burn fat.
L-carnitine can be extremely useful when trying to lose weight, but it is often compared to other weight loss supplements. In this section, we will see how it stacks up against other popular weight loss supplements.
Green tea, which can be drunk in tea form or taken as an extract in pill form, is one of the more popular weight loss supplements and makes our list of Best Natural Fat Burners.
Green tea contains powerful antioxidants called catechins, specifically epigallocatechin gallate (ECCG). These potent antioxidants help aid fat loss by increasing fat oxidation, which is also what L-carnitine does.
Green tea also helps burn fat by increasing metabolism. Both green tea and L-carnitine help increase energy, which is essential during caloric deficits. I personally drink green tea instead of coffee or other caffeinated beverages, and I can attest to the boost in energy it provides.
Although both are effective, studies regarding green tea's effectiveness in helping fat loss are much more extensive than L-carnitine studies. Many fat burners contain both ingredients to maximize weight loss efforts and overall health benefits.
If you want more information regarding green tea, check out our article Is Green Tea Good For Weight Loss?
Another popular supplement often used for weight loss is conjugated linoleic acid (CLA).
CLA is a type of fatty acid that, like L-carnitine, is found in meat and dairy products, although the average diet only gets about 15-175 mg of CLA per day. While both CLA and L-carnitine attack weight loss by increasing fat oxidation, CLA also impacts metabolism. It is believed that CLA helps aid weight loss by influencing enzymes used in fat metabolism and storage.
There is a need for more research regarding the effectiveness of CLA, as studies have had mixed reviews at best. While both ingredients are common in fat burners, L-carnitine is likely better for weight loss as a standalone product.
While CLA, green tea extract, and L-carnitine are all standalone products that help with fat loss, fat burners combine these products for a synergistic effect. Fat burners are elite weight loss supplements because they combine multiple fat-burning ingredients to attack fat from all sides.
Fat burners impact fat loss through a variety of methods, including thermogenic, appetite suppressants, carb blockers, stimulants, and cortisol blockers. The most effective way to target weight loss is using a product that contains L-carnitine and other all-natural products that can target fat in various ways.
You can learn even more about fat burners' effectiveness in our article: Do Fat Burners Work?
Here are some of the most common questions regarding L-carnitine and fat loss.
Yes, L-carnitine helps the body burn fat by using stored fat for energy.
Yes, you can take L-carnitine and creatine together safely. Using them together will increase protein anabolism, leading to greater lean muscle mass and a better body composition.
Yes, you can take L-carnitine and L-glutamine together. L-glutamine is the most abundant amino acid in the body, so taking both will only improve health and increase benefits.
This will depend on several factors, including diet, exercise routine, and genetics, but a review of multiple studies found the average weight loss to be 2.9 pounds.
L-carnitine has been proven to have many health benefits, primarily related to weight loss and improved physical performance. L-carnitine can help boost energy while also helping you recover quicker from your workouts.
The two most important aspects of losing fat are diet and exercise, but supplementing with natural products backed by science, like L-carnitine, can help you reach your goals.
And for the best results, I recommend you try a fat burner that contains L-carnitine while regularly performing a combination of resistance training and cardio.
For help finding the perfect fat burner, take a look at our articles on the 8 Best Fat Burners For Men and the 9 Best Fat Burners For Women. Looking for a stim-free version? We've got you covered with these 9 Best Non-Stimulant Fat Burners!
Comments will be approved before showing up.
September 24, 2023 1 Comment
September 23, 2023
September 21, 2023
At SFS we strive to equip you with the tools and knowledge needed for your fitness journey. Sign up to get the latest on sales, new releases, killer workouts, actionable fitness content and more. As our motto goes - "You don't have to get ready if you stay #alwaysready!"