The benefits of L-carnitine for weight loss are perhaps the main marketing ploy that drives the sales of this supplement today.
Theoretically, L-carnitine should be a good fat burner: after all, its main distinguishing feature is its direct involvement in transporting fats into the cell for conversion into energy.
The key word here is “theoretically.”
In practice, it turns out that the human body is a rather complex system, and the results of scientific studies on the effectiveness of L-carnitine for weight loss are very contradictory. Let’s take a look at some of them.
Main thoughts:
Examine.com: scientific studies do NOT confirm the benefits of L-Carnitine for weight loss
L-carnitine Fat Burner: Scientists AGAINST Sellers
L-carnitine is one of the most controversial weight loss supplements in the world of sports nutrition. This controversy is evident both in the reviews of ordinary users and in the opinions of authoritative portals and individuals. Let’s demonstrate this with an example.
Let’s compare the opinions of a popular online store and an independent scientific portal about the same topic: the benefits of L-carnitine for weight loss.
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Online store bodybuilding.com “on the incredible effectiveness of L-carnitine for weight loss“
It is characteristic of all sellers to exaggerate the advantages of any supplements and drugs, as their earnings depend on it. Look at how this large English-speaking online sports nutrition store bodybuilding.com 3 does it:
“The effectiveness of L-carnitine as a fat burner is unequivocally confirmed. It can be particularly useful during muscle mass gain to protect against fat accumulation. When calorie intake is restricted (for example, during “cutting”), carnitine helps utilize fat cells for energy.
The most important function of carnitine is the transport of fat cells, especially long-chain fatty acid molecules, into the mitochondria of cells. There, they are used as energy to create ATP molecules. This is how fat is burned.
L-carnitine works both when you are resting and when you are training, although its effectiveness is much higher when combined with exercise.
Without sufficient amounts of L-carnitine, most dietary fats cannot enter the mitochondria for burning. With a deficiency of carnitine, the human body is unable to burn fat. A deficiency can lead to muscle weakness, slowed growth, liver enlargement, and a number of other problems.
For this reason, L-carnitine is considered a conditionally essential ingredient: theoretically, the body can synthesize carnitine, but if it is produced in insufficient amounts, it can cause serious harm to health.”
So, what do you think? Is there really any doubt that without carnitine, achieving the perfect body is impossible?
Bodybuilding.com: the effectiveness of L-carnitine for weight loss is unequivocally confirmed; it works as a fat burner both at rest and during workouts, but is especially effective when combined with exercise. With a deficiency of carnitine, the human body is unable to burn fat.
Such bold claims are typical for most sports nutrition sellers.
It is noteworthy that the author of the article is “bodybuilding guru” Jim Stoppani, well-known for his close relationships with certain sports nutrition manufacturers: for them, he conducts scientific experiments and writes articles highlighting the importance and benefits of necessary supplements.
One striking example of this scientist’s “scientific” activity was discussed in the article on the uselessness of BCAA amino acids, where he demonstrated the incredible advantages of BCAA for muscle growth compared to whey protein.
The scientific portal Examine.com on the uselessness of L-carnitine for weight loss
Now consider the alternative viewpoint of scientists from Examine.com – a portal whose mission is to provide an objective scientific perspective on the benefits or uselessness of various supplements based on the analysis of scientific data 4:
“From a theoretical point of view, the fat-burning effect of L-carnitine is explained by its involvement in the transport of fatty acids into the mitochondria of cells for use as fuel.
This property partly explains the accumulation of carnitine in muscles and the heart – tissues that use fat cells as fuel.
However, for the most part, scientific research on both humans and animals DO NOT confirm the benefits of L-Carnitine for weight loss 1,2.
Exceptions are conditions of its deficiency: veganism, vegetarianism, old age, where additional intake of carnitine can indeed be accompanied by a fat-burning effect 7,8.“
Examine.com: scientific research DOES NOT confirm the benefits of L-Carnitine for weight loss
Below we will provide scientific evidence of the questionable effectiveness of L-carnitine for weight loss.
Scientific studies on the effectiveness of L-Carnitine for weight loss are contradictory
Examine:
“At the cellular level, the consumption of carnitine as a supplement does indeed cause some changes in the body that increase the potential for more efficient burning of fat cells for energy, especially in combination with physical exercise, but the rate of burning total fat mass, glucose, and glycogen does not change, the weight loss process is not initiated” 4.
1: Experiment: The Uselessness of L-carnitine for Weight Loss in Overweight Women
The study involved 36 moderately overweight women. They were paired with approximately the same body mass index: one group took L-carnitine, while the other took a placebo (“dummy”). The dose of carnitine for weight loss was 2 g twice a day. The placebo group took lactose instead of carnitine. All participants walked for 30 minutes a day at a moderate pace, 4 days a week.
After 8 weeks of the experiment, the researchers found no changes in body weight and concluded that the consumption of L-carnitine is useless for weight loss. Five women taking carnitine did not complete the experiment due to nausea and diarrhea that began 1.
In the experiment involving overweight women, the benefits of L-carnitine for weight loss were not confirmed
1 Experiment: The Uselessness of L-carnitine for Weight Loss in Dieting Rats
24 rats were divided into two groups; all were fed food with a caloric value half of the basic needs for sustaining life; one group was given 5 g/kg of L-carnitine, while the other was not. The duration of the experiment was 23 days.
Result: the administration of carnitine to rats did NOT show advantages for “weight loss” and improvement of body composition (ratio of muscle and fat mass) 9.
3 Experiment: The Benefits of L-Carnitine for Weight Loss in Swimming Rats 😉
Hypothesis: if rats leading a “sedentary” lifestyle are “given” L-carnitine for 5 weeks, it will lead to weight loss, and the effect will be enhanced with additional physical activity in the form of swimming.
Result: additional administration of carnitine did NOT lead to a reduction in fat mass, including visceral fat. Moreover, those rats that received L-carnitine gained weight while consuming the same caloric intake 10.
Scientific studies refute the effectiveness of L-Carnitine for weight loss in animal experiments (rats)
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4 Experiment: Intense Cycling + L-Carnitine for Weight Loss?
In this study, scientists attempted to determine how L-carnitine affects fat burning when cycling for 90 minutes every day.
15 cyclist athletes were divided into two groups: one group takes 3 g of L-carnitine-L-tartrate daily, while the other receives a placebo (“dummy”).
The scientists’ conclusion after 4 weeks of the experiment: the intake of L-carnitine for weight loss has no effect under any physical loads 5.
Similar results have been obtained at different times in other experiments.
L-carnitine in combination with intense physical activity is useless for weight loss
To be fair, it should be noted that there are studies that confirm some effectiveness of L-carnitine for weight loss.
In one meta-analysis of 9 scientific studies, the author notes that, on average, L-carnitine helps to lose 1.3 kg more than without it. It also mentions that the effectiveness of fat burning when consuming carnitine significantly decreases over time 6.
It is also important to note that the participants in most of the studies taken as a basis were individuals suffering from obesity or elderly people.
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Conclusion
Theoretically, L-carnitine should be a good fat burner, which is explained by its role in transporting fats into cells for energy production.
However, based on the available data, it is impossible to definitively state that L-carnitine is effective for weight loss. More research is needed across different age groups and people of varying activity levels.
The degree of fat burning observed in some positive experiments is comparable in effect to that seen with simple, relatively mild calorie restriction in the diet.
The benefits of L-carnitine for weight loss have not been definitively proven scientifically either in rats or in humans.
Theoretically, L-carnitine has several mechanisms for increasing the rate of fat burning, but in practice, its effectiveness lacks definitive confirmation.
