Written by Garett Reid | NSCA, CSCS, CISSN, M.S.E.S.S
Fact checked by Andrew Lenau, ISSA CPT & Sports Nutritionist
FACT CHECKED
We may earn a commission on purchases made through links on this page at no cost to you. Learn More
Doesn't the search for the perfect weight loss supplement feel like a never-ending quest?
This mission to find an effective weight loss product is made even more challenging due to the fact that pretty much all supplements associated with metabolism or fat metabolism are quickly yielded as miracle drugs. But, remember, just because something claims to aid in weight loss, doesn't mean it actually does.
When in doubt, always let the research guide you.
So, what does the research say about L carnitine? Is it good for weight loss? And if so, how does it work and how much can you expect to lose?
Let's see what science says about it.
Table of Contents:
- What is L Carnitine?
- What Does L Carnitine Supplementation Do?
- Is L Carnitine Supplementation Good For Weight Loss?
- How Is L Carnitine Good For Weight Loss?
- How Much Weight Can L Carnitine Help You Lose?
- Does L Carnitine Burn Fat?
- How Much L Carnitine Should You Take For Weight Loss?
- When Should You Take L Carnitine For Weight Loss?
- Additional L Carnitine Benefits
- Potential L Carnitine Drawbacks & Side Effects
- Who Should & Shouldn't Take L Carnitine
- What Is The Best L Carnitine Supplements For Burning Fat?
- Tips For Taking L Carnitine
- FAQs
What is L Carnitine?
This is a mouthful, so hang in there for the next few sentences.
L-carnitine is a quaternary ammonium cation compound that is found in the muscle mass of humans and animals. In fact, this is where it gets its name, from the Latin word "carus," meaning meat.
It's composed of the two amino acids lysine and methionine¹. To put it simply, L carnitine is a naturally occurring amino acid that's produced by the body and plays a role in energy production, as it transports fatty acids.
Your cells, specifically the mitochondria, take L carnitine and create usable energy with it.
What Does L Carnitine Supplementation Do?
L carnitine supplements will correct an L-carnitine deficiency. Depending on your diet and health, you may or may not have full stores, similar to the way creatine works.
If your body has a lack of L-carnitine, it can lead to suboptimal performance in fat metabolism, causing less fat to be metabolized and less usable energy to be made.
A carnitine deficiency can occur in two ways. The first, as mentioned, is because of your diet. Individuals who eat a small amount of meat, or none altogether, as vegans do, will experience significantly lower levels of L-carnitine.
The second group of people who may lack L carnitine are those with issues related to their kidneys, such as chronic renal failure. Taking a daily L-carnitine supplementation of 20–200 mg/kg/day can help resolve deficiencies¹.
Is L Carnitine Supplementation Good For Weight Loss?
Due to its role in the metabolism of fatty acids, many people have looked to L carnitine supplementation to aid in the loss of fat mass.
Fortunately, there has been a lot of research done on its role in weight loss. And after examining this research, in my professional opinion, L carnitine does, in fact, help promote weight loss in individuals, especially those who are overweight².
We're about to talk about this in detail, but for even more information, you can also check out our article: L Carnitine For Weight Loss: Does It Actually Work?
How is L Carnitine Good For Weight Loss?
L carnitine's primary role in the human body is to support mitochondrial function and energy production. In terms of weight loss, it's this role in energy production that plays the largest role in dropping pounds.
L-carnitine is used to transport fatty acids into the mitochondria. Once inside the cells, L-carnitine transports long-chain fatty acids into the mitochondria, the cell's "powerhouse." Once the fatty acids are inside, it is then broken down to increase adenosine triphosphate (ATP).
By ensuring your L-carnitine stores are maxed out, you are optimizing fat metabolism. This means that more fatty acid oxidation is increased, and more fat is utilized.
How L Carnitine Supplementation Can Help You Lose Weight
Remember, if your natural carnitine levels are low, you are reducing your body's ability to metabolize fat. As a result, L-carnitine supplementation will top out your levels to ensure your metabolism is working at full capacity.
In addition, L-carnitine can bind to certain amino acids that may be potentially used for energy production¹. In fact, this is what happens when we are in too much of a deficit, as the body requires energy.
Unfortunately, this means our muscles can break down. But when our L-carnitine levels are full, we can potentially preserve our muscle mass and force our body to look to other sources, either glucose or fat, for energy production.
This is crucial, as no one wants to put in the work to build muscle, only to have their body use precious muscle mass for energy.
How Much Weight Can L Carnitine Help You Lose?
There are a lot of factors to consider when estimating the magnitude of weight loss a person may see. One review of 9 studies found that those who took L carnitine saw an average of 2.9 lbs (1.3kg) more weight loss compared to those who didn't³.
Another review and meta-analysis found that the weight loss difference was 2.67 pounds (1.21kg)⁴. Being that these numbers are so similar, it's safe to expect to lose an additional 2 to 3 pounds total compared to if you did not supplement with L carnitine.
Does L Carnitine Burn Fat?
Yes! L-carnitine is responsible for transporting fatty acids to the mitochondria to be broken down for ATP. So while L-carnitine doesn't directly burn fat, it plays a pivotal role in the process.
What Are The Best L Carnitine Supplements For Burning Fat?
When you first start looking for an L-carnitine supplement, you first need to keep in mind there is more than one form of carnitine. While L-carnitine is the natural form of carnitine, there are different types that exist.
There are four common forms, so let's review each.
- D-Carnitine: D-carnitine is an inactive form of carnitine. Being so, it can take up room in your carnitine stores, thus preventing the absorption of active forms. You definitely don't want this, so I'd suggest avoiding D-carnitine if you happen to come upon any⁵.
- Propionyl-L-Carnitine: Propionyl-L-carnitine is generally the preferred form for those with circulatory issues. This includes ailments such as peripheral vascular disease and high blood pressure. It may also help increase nitric oxide, which can improve blood flow.
- L-Carnitine L-Tartrate: L-carnitine L-tartrate is generally the form of carnitine most often used to improve athletic performance and increase fat loss. It's believed to have a better ability to burn fat.
- Acetyl-L-Carnitine: Acetyl-L-carnitine is the most common form used to improve brain health and increase cognition. It may also help fend off neurodegenerative diseases.
Generally speaking, most people should look at supplementing with either acetyl-L-carnitine or L-carnitine L-tartrate.
You should always look for the purest forms of an L carnitine supplement, and keep quantity in mind. Two grams a day seem to be the sweet spot for optimal results.
Another factor you need to consider is whether you want to take a single-ingredient supplement or a fat burner with multi ingredients. The fat-burning option can be a great option for those who are looking to maximize their weight loss due to the various other fat-burning compounds included.
Let's take a look at some specific L carnitine supplement options.
1) Fat Burners With L-Carnitine:
For fat burners with L-carnitine, I have two great options. The first non-stimulant option is Kaged Muscle Clean Burn. Each serving packs 1,000mg of carnipure along with several other potent fat-burning compounds such as capsicum and green tea extract.
While most weight-loss formulas only address one of the typical person’s weight management challenges, Clean Burn™ attacks the problem from multiple angles! Losing weight is...
The second fat burner with L-carnitine I'd recommend is Transparent Labs Stim-Free. Unlike Kaged, it used 750mg of acetyl-L-carnitine. However, it hosts a wide range of other fat-burning compounds, such as 5-HTP and cayenne pepper.
With a unique combination of clean and natural fat burning ingredients, PhysiqueSeries Fat Burner Stim-Free is perfect for anyone intolerant to stimulants looking...
2) Single Ingredient L-Carnitine Products:
Now, if you're looking for pure L-carnitine, your main focus should be examining and comparing quality vs. price.
My recommendation for a great L carnitine supplement is from the awesome budget-friendly supplement company NOW. NOW L-Carnitine includes 100 tablets, each with 1,000mg of pure Carnipure, for just under $27. They are a bit more expensive due to being tablets, but they are still cost-effective.
Another option comes from Nutricost, delivering 250 servings of L-carnitine L-Tartrate for about the same price as NOW. While they don't seem to use Carnipure, it is still high quality, and you get 2.5x more for those on a tight budget.
How Much L Carnitine Should You Take For Weight Loss?
Most studies use a range of dosing from 500mg up to 4,000mg. That said, it seems as though 2,000mg daily is the sweet spot for weight loss.
When Should You Take L Carnitine For Weight Loss?
As of today, there is limited information concerning the best times to take l carnitine supplements. Having said that, I'd recommend taking it after your workout.
You can learn more about this in our article: When to Take L-Carnitine: Best Time & Dosage.
Additional L Carnitine Benefits
While L carnitine supplementation is usually used for weight loss, that's not it's the only reason you may want to take it. In fact, the benefits of l carnitine supplementation are quite significant.
Here is a list of additional benefits of L carnitine. Keep in mind these have varying degrees of evidence to back their use.
- Improves brain function
- Increases chance of pregnancy
- Increases production of sperm
- Reduces the risk of myocarditis
- Increases heart health
- Improves athletic performance
Potential L Carnitine Drawbacks & Side Effects
While L-carnitine has a lot of benefits, there are a few drawbacks and unwanted side effects. Here are some things you need to consider.
One of the unwanted side effects of L carnitine supplementation is that it can cause several gastric issues. In one study from 2000, 5 of 18 participants experienced either diarrhea or nausea from L carnitine supplements and were unable to complete the study⁶.
There is also evidence that prolonged L carnitine administration can raise a compound called trimethylamine N-oxide (TMAO). This compound has been found to increase the chance of developing atherogenesis, the formation of fatty acids in the arteries⁷.
The last drawback, which seems to be more common than normal use, is gastric issues. As mentioned above, some people experience nausea or diarrhea, so always start with a smaller dose to see how your body adapts.
Who Shouldn't Take L Carnitine?
Since L carnitine supplements merely raise the level of carnitine, it doesn't make sense for those who already get a lot through their diet. Therefore, people who eat a large amount of red meat and fish are probably less likely to see significant weight loss.
It's important to realize that your body has a threshold for the amount o Ll-carnitine it can utilize. Any extra amount will be stored in the kidneys or even expelled if needed. Alternatively, if you eat a lot of red meat and are concerned about cardiovascular disease, L carnitine supplements may be a smart option for supporting your heart health.
In addition, it seems that L-carnitine supplements work best in those who are overweight. This likely has something to do with a threshold for its effectiveness. Therefore, individuals who have great body composition will likely see fewer results, if any.
In addition, individuals with certain health conditions should stay away. This includes those:
- With a history of seizures
- Who have kidney disease or on dialysis (it places stress on the kidneys)
- Those who take blood thinner
- Women who are breastfeeding or pregnant (not enough is known, so err on the side of caution)
Who Should Take L Carnitine Supplements?
With some basic reasoning skills, we can conclude that everyone that doesn't fit into the above categories can go ahead and take L-carnitine supplements. However, there are some people who will likely see the best results.
Vegans are the first group of people who will probably see great results. This is because their natural levels are low due to them not consuming meat and having an L-carnitine deficiency⁸. As a result, they will see a greater increase in carnitine levels which theoretically relates to greater improvements in performance.
So, if you're following a vegan bodybuilding diet, definitely consider supplementing with L carnitine!
In addition, those who have a high body mass index and are overweight may see the best results from l carnitine supplementation.
How To Optimize Results From L-Carnitine Supplementation
While taking l carnitine supplements can possibly help aid with fat loss, it's not a magic pill. It's not so potent that it can outweigh the effects of poor nutrition and inactivity. Therefore, if you are serious about losing weight, you must combine your supplementation with a healthy diet and regular exercise.
My suggestion? Find a workout split you can stick to and give this meal plan for weight loss a shot!
FAQs
Let's answer any remaining L-carnitine questions you have here.
Does L-carnitine reduce belly fat?
While l-carnitine can be effective in reducing body fat, it does not specifically target body fat. The location where people lose and gain fat first is completely genetic. Generally speaking, you will lose fat in the reverse order you gained fat.
How much weight can you lose with L-carnitine?
There are a lot of factors to consider when estimating the magnitude of weight loss a person may see. However, one review of 9 studies found that people who took L-carnitine lost an average of 2.9 pounds (1.3kg) more than those who didn't.
How does L-carnitine work for weight loss?
L-carnitine supports fatty acid oxidation by transporting fatty acids to the mitochondria to be broken down for energy.
How long does it take for L-carnitine to work?
There is no specific timeline but it seems as though 4 weeks is the minimal amount of time to wait.
Research Shows L-Carnitine Helps With Weight Loss
L-carnitine has been shown to be an effective supplement for some populations. While the results may be mixed, it does seem to be promising enough to try if you're interested.
Further, we also need to consider the plethora of other possible benefits that you may receive.
The bottom line is that L-carnitine is a vital compound for not just fat loss but optimal human performance. As it is relatively cheap, it definitely wouldn't hurt to try if you think you may have a deficiency.
Just be sure to monitor your reactions and how you feel. Only then can you truly determine whether you need it.
Interested in boosting your weight loss with L carnitine? Check out NOW L-Carnitine, a great L carnitine supplement that is effective and reasonably priced. Or, for those looking for a multi-ingredient product, Kaged Muscle Clean Burn is a great fat burner option that contains L carnitine and multiple other weight loss ingredients.
For additional multi-ingredient weight loss products, check out our article on the 9 Best Non-Stimulant Fat Burners.
References:
- Longo N, Frigeni M, Pasquali M. Carnitine transport and fatty acid oxidation. Biochim Biophys Acta. 2016. doi:10.1016/j.bbamcr.2016.01.023
- Talenezhad, N., Mohammadi, M., Ramezani-Jolfaie, N., Mozaffari-Khosravi, H., & Salehi-Abargouei, A. (2020). Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis. Clinical nutrition ESPEN. https://doi.org/10.1016/j.clnesp.2020.03.008
- Pooyandjoo, M., Nouhi, M., Shab-Bidar, S., Djafarian, K., & Olyaeemanesh, A. (2016). The effect of L-carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials. Obesity reviews : an official journal of the International Association for the Study of Obesity. https://doi.org/10.1111/obr.12436
- Talenezhad, N., Mohammadi, M., Ramezani-Jolfaie, N., Mozaffari-Khosravi, H., & Salehi-Abargouei, A. (2020). Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis. Clinical nutrition ESPEN. https://doi.org/10.1016/j.clnesp.2020.03.008
- Matsuoka M, Igisu H (July 1993). "Comparison of the effects of L-carnitine, D-carnitine and acetyl-L-carnitine on the neurotoxicity of ammonia". Biochemical Pharmacology.
- Villani, R. G., Gannon, J., Self, M., & Rich, P. A. (2000). L-Carnitine supplementation combined with aerobic training does not promote weight loss in moderately obese women. International journal of sport nutrition and exercise metabolism. https://doi.org/10.1123/ijsnem.10.2.199
- Samulak, J. J., Sawicka, A. K., Hartmane, D., Grinberga, S., Pugovics, O., Lysiak-Szydlowska, W., & Olek, R. A. (2019). L-Carnitine Supplementation Increases Trimethylamine-N-Oxide but not Markers of Atherosclerosis in Healthy Aged Women. Annals of nutrition & metabolism. https://doi.org/10.1159/000495037
- Rebouche C. J. (1992). Carnitine function and requirements during the life cycle. FASEB journal : official publication of the Federation of American Societies for Experimental Biology.
Garett Reid
Author