24 January 2006

L-carnitine and slimming

L-Carnitine is all the rage at the moment and countless slimming products that contain this compound claim that it will melt your fat away. So what are the facts?

Readers keep on asking me if L-Carnitine will help them to lose weight. L-Carnitine is all the rage at the moment and countless slimming products that contain this compound claim that L-Carnitine will melt your fat away or help you to burn excess fat.

Can L-Carnitine help you lose weight?

The answer to this question is a resounding no. To understand why Carnitine does not promote weight-loss, we need to have a look at what this compound actually does in the human body.

Biochemistry of Carnitine

Carnitine is synthesised in humans from two of the so-called ‘essential amino acids’, lysine and methionine. It is also believed that vitamin B6 is necessary for the synthesis of Carnitine.

Research has shown that Carnitine plays an important role in transporting fatty acids into the mitochondria. The mitochondria are those parts of body cells, which act like power houses and make energy available to the body.

So if Carnitine helps produce energy in the human body, why can’t it help with weight-loss? Carnitine does transport fatty acids into the mitochondria, but it cannot fetch fat stored in the hips and thighs and tummy and burn it up. Sad, but true!

The amount of Carnitine made by the human body is generally not sufficient to meet bodily requirements, so we need to obtain some Carnitine from our diet. Meat and dairy products like milk, cheese and yoghurt, are rich sources of Carnitine.

Carnitine deficiency

A Carnitine deficiency can cause a condition called acute encephalopathy with vomiting, mental confusion and sleepiness. Patients with a Carnitine deficiency tend to suffer from muscle weakness, as is the case in babies with ‘floppy-baby syndrome’.

A lack of Carnitine can also affect brain function and it is essential that baby formulas contains some L-Carnitine to ensure proper brain development.

L-Carnitine supplements are used for individuals with a defined Carnitine deficiency, babies with ‘floppy-baby syndrome’ and individuals who develop a deficiency, because they take certain of the anti-epileptic drugs which contain a chemical called ‘valproic acid’. In such cases, the use of L-Carnitine is indicated and plays an important role in improving muscle tone, and brain function and preventing encephalopathy.

Children at Risk of Carnitine deficiency

People at risk of Carnitine deficiency are mainly children with floppy muscles or hypotonia, failure to thrive, repeated infections, encephalopathy, hypoglycaemia and heart muscle infections. If these children are treated with L-Carnitine their symptoms generally improve.

It stands to reason that anyone who eats a strict vegetarian or vegan diet, which excludes all milk, dairy products, meat, fish and eggs, also runs the risk of developing a Carnitine deficiency. It may, therefore, be a good idea for strict vegetarians and vegans to take an L-Carnitine supplement.

L-Carnitine and Exercise

L-Carnitine has been hailed as a so-called ‘ergogenic compound’. In other words, L-Carnitine is supposed to increase athletic performance. The logic goes like this - if Carnitine improves fat oxidation (efficient energy release obtained from burning fat) then it should also improve athletic performance.

Because of this possible link between L-Carnitine and athletic performance, a number of carefully controlled scientific studies were conducted to determine if supplementation with L-Carnitine boosts muscle levels of Carnitine and therefore provides athletes with more energy. All these studies found no increase in muscle Carnitine levels when athletes took L-Carnitine supplements.

There is thus no scientific evidence that L-Carnitine can improve athletic performance. Always remember that the best way of boosting your athletic performance is to eat a high-carbohydrate diet.


Thanks to scientific studies we now know the following about Carnitine:

  • Carnitine is important to prevent certain diseases like ‘floppy-baby syndrome’ and encephalopathy
  • L-Carnitine supplements can be used for children suffering from the above mentioned diseases, individuals who are at risk of Carnitine deficiency, because they take anti-epileptic drugs or eat a Carnitine-deficient diet
  • L-Carnitine does not promote weight-loss
  • L-Carnitine does not promote athletic performance

The promises made by manufactures of slimming products and sports performance boosters that contain L-Carnitine are therefore just so much wishful thinking. You will achieve more weight-loss if you eat a low-fat, high-fibre diet and improve your athletic performance dramatically if you eat a high-carbo diet, than if you swallow all those expensive L-Carnitine supplements.


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