L-carnitine | Is it good for weight loss? When to take? Dosage?

When you exercise, a thousand biochemical reactions are taking place inside your body. Glycogen is taken from the inside of muscle cells and broken down into glucose and enters your bloodstream which carries into the mitochondria. Enzymes come into action and start to break down stored fat into fatty acids and glycerol to be used as fuel throughout the exercise.

The intensity and duration that you’ll be able to put in your workout depends on how optimized your body is at using fat for fuel. Wouldn’t it be nice if there was a supplement that could boost fat oxidation and let you keep exercising longer?

Well, in fact there is. It is called L-carnitine and has been used for athletes from different sports around the world to improve performance. It is one of the most popular supplements for weight loss and fat burning.

What is L-carnitine?

L-carnitine is a non-essential (sometimes conditionally-essential) amino acid that plays a crucial role in the transfer of fatty acids to the mitochondria (1). Natural sources of L-carnitine include animal-derived products, such as white and red meat, fish and milk.

L-carnitine weight loss and performance, the effects

Scientific literature shows that supplementation with L-carnitine on a daily basis increases the blood and muscular concentrations of this amino acid, enhancing fat metabolization and subsequent better performance.

Nevertheless, the researchers pointed out that muscle lactate was reduced when performing high-intensity exercise (at 80% VO2max).

This was not the first study to show that L-carnitine supplementation is able to reduce various markers of metabolic stress and of muscle soreness. Similar results were found by Spiering et. al. (2007) (3) and Jacobs et. al. (2009) (4).

When to take L-carnitine? What is the proper dosage?

Studies have shown that the L-carnitine-carbohydrates combo has ergogenic effects and can increase work output by 11%. So you should take your L-carnitine supplement with a reasonable amount of fast-acting carbohydrates (60g of dextrose or maltodextrin.)

The “before or after workout” dilemma doesn’t seem to be the most important factor when considering L-carnitine supplementation. Rather, take it daily for some weeks and you should be able to see some solid results.
As for the dosage, aim for 2-4g of L-carnitine daily.



1 – Altern Med Rev. 1998 Oct;3(5):345-60

2 – J Physiol. 2011 Feb 15;589(Pt 4):963-73

3 – J Strength Cond Res. 2007 Feb;21(1):259-64

4 – J Int Soc Sports Nutr. 2009 Apr 2;6:9

Mr Protein

Mr Protein

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