Does L-Carnitine work?

Does L-Carnitine supplementation really lose fat?

L-Carnitine is one of the most well-known supplements when it comes to losing fat, whether in ampoules or capsules, liquid or powder, if you haven't taken it, you certainly know someone who has already taken it.

The big question is… does it work?

First of all, L-Carnitine has several benefits, but we will rely on only one: fat loss.

That is, it can even be effective for several things, but here we will only evaluate its effectiveness in this regard.

So let's get started.

What is L-Carnitine?

AL Carnitine is a compound that is synthesized by the body, through lysine and methionine.

In addition to being able to be synthesized through these amino acids, it is found naturally in some foods, mainly in meats.

FoodAmount L-Carnitine per 100g
Chicken breast3.9mg


The great theory behind the use of this supplement by those who want to lose weight, is that this compound promotes a greater use of fats.

This on paper makes sense, since L Carnitine binds to fatty acids and allows them to enter the mitochondria to be used as energy.

Theoretically, by increasing Carnitine levels, we would get more fatty acids to be used for energy, and thus more fat would be burned.

But what makes sense in theory is not always confirmed in practice.

l-carnitine works

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The absorption of L-Carnitine through food is 54% to 87%, while through supplementation it is only 14% to 18%. (1)

That is, when you drink that vial with a horrible taste, only 14% to 18% is really absorbed.

In addition, it is important that this L-Carnitine reaches the muscle, and that is not quite what happens. (9)

But let's get to what really matters, burning fat.

Does not work

Unfortunately, there are not many studies in relation to L-Carnitine in fat loss, but we will use what exists.

Second This one study, a low-calorie diet supplemented with L-Carnitine, had no advantage in terms of fat loss over a low-calorie diet without L-Carnitine. (2)

This study was done on rats.

Now let's move on to humans.

In this study, moderately obese women were compared, in which one group used 4g of L-Carnitine per day for eight weeks, while the other group did not. (3)

There was no difference between groups in terms of results.

In this study looked at whether L-Carnitine could actually promote greater use of fats, and the results indicate that it did not.(4)

In this study, it was evaluated whether L-Carnitine could promote fat loss in medicated bipolar people.

Two groups were created, both following similar diets, in which one group used a L-Carnitine supplement and the other did not, for 26 weeks.

The results were similar between the two groups.(5)

It is complicated.

Doesn't L-Carnitine really work?

l-carnitine works

It works

In this study, 66 people were recruited to test the effectiveness of this supplement. (6)

These 66 people were separated into two groups, one received 2g of L-Carnitine per day, while the other did not.

The results were positive, with not only a decrease in body fat, but also an increase in muscle mass.

The only problem is, the people used in this study were centenarians, that is, people over 100 years old.

If you are over 100 years old, this study shows that this supplement works.

This one study proves the same, loss of fat mass and increase of muscle mass.(7)

For the end, we left the best.

In 2011 a study was presented that showed that supplementation with this compound can really be effective.

This one study shows that L-Carnitine supplementation, in conjunction with carbohydrates, leads to a significant increase in carnitine in the muscle, and a consequent increase in fat oxidation.

The form of Carnitine used in this study was L-Tartrate, in a dose of 2g together with 80g of carbohydrates, twice a day. (8)

The bad news is that the efficacy only exists in the long term, and it takes 6 months for L-Carnitine to show good results.


L-Carnitine if it works in healthy people, in a fat loss component, it will only be in the long run.

Those who may also benefit from this supplement are people with low carnitine values, such as the elderly, where studies show that there is a benefit, and vegetarians, who do not have a significant dietary source of L-Carnitine.

The balance we can make is that if you are thinking of using this supplement for a month to gain some beautiful abs, good luck, you will need it.

The typical approach of buying a box of ampoules, or a bottle of L-Carnitine, and taking it for a few weeks, does not work.

If, on the other hand, you are willing to use this supplement for the long term, or have low carnitine levels, L-Carnitine may be a good bet.

The big problem with this supplement to move from theory to practice, seems to be absorption, and the levels of carnitine in muscles in most studies have not increased.

Insulin seems to favor the absorption of L-Carnitine into the muscle, so it will be a good strategy to use this supplement in conjunction with a high carbohydrate meal.

Oh, and use for at least 6 months!


(1) Rebouche CJ. Kinetics, pharmacokinetics, and regulation of L-carnitine and acetyl-L-carnitine metabolism. Ann NY Acad Sci. 2004 Nov; 1033: 30-41. (2) Brandsch C, Eder K. Effect of L-carnitine on weight loss and body composition of rats fed a hypocaloric diet. Ann Nutr Metab. 2002; 46 (5): 205-10. (3) Villani RG, Gannon J, Self M, Rich PA. L-Carnitine supplementation combined with aerobic training does not promote weight loss in moderately obese women. Int J Sport Nutr Exerc Metab. 2000 Jun; 10 (2): 199-207. (4) Broad EM, Maughan RJ, Galloway SD. Carbohydrate, protein, and fat metabolism during exercise after oral carnitine supplementation in humans. Int J Sport Nutr Exerc Metab. 2008 Dec; 18 (6): 567-84. (5) Elmslie JL, Porter RJ, Joyce PR, Hunt PJ, Mann JI. Carnitine does not improve weight loss outcomes in valproate-treated bipolar patients consuming an energy-restricted, low-fat diet. Bipolar Disord. 2006 Oct; 8 (5 Pt 1): 503-7. (6) Malaguarnera M, Cammalleri L, Gargante MP, Vacante M, Colonna V, Motta M. L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial. Am J Clin Nutr. 2007 Dec; 86 (6): 1738-44. (7) Pistone G, Marino A, Leotta C, Dell'Arte S, Finocchiaro G, Malaguarnera M. Levocarnitine administration in elderly subjects with rapid muscle fatigue: effect on body composition, lipid profile and fatigue. Aging Drugs. 2003; 20 (10): 761-7. (8) Wall BT, Stephens FB, Constantin-Teodosiu D, Marimuthu K, Macdonald IA, Greenhaff PL. Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. J Physiol. 2011 Feb 15; 589 (Pt 4): 963-73. (9) Barnett C, Costill DL, Vukovich MD, Cole KJ, Goodpaster BH, Trappe SW, Fink WJ. Effect of L-carnitine supplementation on muscle and blood carnitine content and lactate accumulation during high-intensity sprint cycling. Int J Sport Nutr. 1994 Sep; 4 (3): 280-8.

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