L-carnitine and the weight loss theories

What the research is saying.

Mitochondria are one of the organelles within the cell.

L-Carnitine is one of the chemicals which acts as a carrier transporting long chain fatty acids across the mitochondrial membrane. Mitochondria are small bodies or organelles within your body's cells, that help the cell produce energy.

L-carnitine is synthesized in the liver and kidneys and then transported around the body^[1]. Some think that L-carnitine can burn fat by increasing fat oxidation instead of allowing the fat to be stored.

L-Carnitine and Weight Loss Research Title:

The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects.

Year Published: 2004

Research Summary: Researchers used a technique called a tracer technique to find out if L-carnitine supplements effect fat oxidation, protein turnover, body composition, and weight development in the overweight. 3 g per day were given to the treatment group over 10 days. These researchers found that the L-carnitine supplementation led to a significant increase in fat oxidation, while protein synthesis was relatively unchanged.

National Library of Medicine Wutzke KD, Lorenz H. The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects. Metabolism. 2004 Aug;53(8):1002-6. Abstract

L-Carnitine and Weight Loss Research Title:

Carnitine supplementation fails to maximize fat mass loss induced by endurance training in rats.

Year Published: 2004

Research Summary: This study aimed to evaluate the effect of L-carnitine supplementation on wistar rats, and what if any effect it would have on fat mass loss in the animals.

The rats were divided into groups where some were given a daily dose of 28 mg per kg of L-carnitine, some were exercised as well as receiving the supplementation and some received only the supplementation. A control group of rats were used as a baseline and a group was also included in the study that were exercised only without any supplementation being given.

After 14 days, the animals were killed and their carcasses assessed for fat content as well as weight and fat content of the adipose tissues. It was observed by the researchers that although the L-carnitine was present in the mitochondria the presence did not have an effect on fat mass loss for the rats. Effective fat mass loss was observed for the rats who received only exercise. In other words the L-Carnitine supplement had no effect on losing body fat.

National Library of Medicine Saldanha Aoki M, Rodriguez Amaral Almeida AL, Navarro F, Bicudo Pereira Costa-Rosa LF, Pereira Bacurau RF. Carnitine supplementation fails to maximize fat mass loss induced by endurance training in rats. Ann Nutr Metab. 2004;48(2):90-4. Abstract

L-Carnitine Weight Loss Research Title:

Effect of L-carnitine on weight loss and body composition of rats fed a hypocaloric diet.

Year Published: 2002

Research Summary: 36 rats were divided into treatment and control groups. The treatment group was given 5 g per kg of L-carnitine over 23 days, all rats underwent a calorie controlled diet. The rats did lose weight however, the group receiving the L-carnitine did not show significant improvement in body composition.

National Library of Medicine 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. Abstract

L-Carnitine Weight Loss Research Title:

Pharmacokinetics and safety of l-carnitine infused i.v. in healthy subjects.

Year Published: 1988

Research Summary: Researchers tested dosages of 20, 40 and 60 mg per kg of l-carnitine on 10 healthy subjects through I.V infusions. The researchers observed no objective or subjective side effects to the drug when administered by IV at any of the dosage levels, so is considered to be safe at the above dosage levels.

Conclusions about L-Carnitine and Weight Loss:

L-carnitine is a natural chemical that is synthesized by our bodies assisting the mitochondria to perform its vital functions. There are differing views as to whether its supplementation actually does produce an increase in fat oxidation and fat mass loss.

While the above studies have shown that it fails to cause fat mass loss in rats, it does result in fat oxidation within human cells, giving rise to the theory that it may be able to burn fat at the cellular level. L-carnitine seems to be a safe supplement to take.

No ill effects have been reported in the studies done and within I.V. infusions, it seems to be safe for humans to take dosages up to 60 mg per kg. Some studies have given 3 grams of L-carnitine with no side effects. The use of L-carnitine in weight loss supplements may be beneficial in losing weight when used under medical supervision.

References:

[1] Oregan State University Linus Pauling Institute

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