What Is Carnitine?

Carnitine, or L-carnitine as it’s commonly referred to, is classified as a non-essential amino acid. The liver, brain and kidneys produce it from the essential amino acids methionine and lysine. Amino acids stimulate protein synthesis. However, carnitine is different. This is because it transports long-chain fatty acids into the mitochondria for energy production. The result of this process is to provide muscular energy by burning fat. Its name comes from the fact that it was first isolated from meat in 1905 ( carnivore or meat eater), and initially termed vitamin B-t.

It can also be the generic term for a number of compounds that include L-carnitine, L-acetyl carnitine, acetyl-L-carnitine, and L-propionyl carnitine. However, most people see it as a common fat loss ingredient found in numerous fat loss products. More recently, there have been a few specialized formulas which combine different types or versions of carnitine into one product. The advantage is that this combination results in numerous benefits not obtainable with standard l-carnitine. However, most people will use this as part of their fat loss strategy.

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Benefits Of Carnitine

  • The primary benefit is that carnitine helps burn fat for energy, contributing towards fat loss and muscular energy.
  • Research is ongoing regarding other potential benefits of carnitine, such as: heart health, brain health and infant nutrition, among others.

In these supplement guides, specifically creatine, I have talked about the energy systems of the body. Read about carnitine and it’s role in energy production to see how it ties into the discussion regarding creatine. It ties in with the Aerobic Glycolytic System, or the Oxygen System.

The main source of energy for this system is carbohydrates from muscle stores and the blood stream, and stored fats. In order for this system to work there needs to be oxygen present. The waste products are carbon dioxide, which we exhale, and water. This system, if the activity is not too intense, can continue indefinitely assuming the body has glucose, fat, and oxygen. However, if the activity is too intense then glucose may run out, and the body will produce lactic acid. This is oxygen deficit.

Also, no single system works by itself. The duration and intensity of the activity will determine which system is the primary one. However, they are all used to some degree.

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Studies Done On Carnitine

Additionally, carnitine is a mainstay of various fat loss formulas, from thermogenics to stim-free products. Numerous studies have been done on carnitine as far back as 1937. Included here are two examples.

Study # 1

The effect of l-carnitine on fat oxidation, protein turnover, and body composition in slightly overweight subjects. Metabolism. 2004 Aug;53(8):1002-6. We used a combined tracer technique with the stable isotopes (13)C and (15)N to gain further insight into the metabolic changes that accompany supplementation of l-carnitine. The aim of the present study was to investigate whether l-carnitine supplementation can influence fat oxidation, protein turnover, body composition, and weight development in slightly overweight subjects.

Twelve volunteers received an individual regular diet either without or with l-carnitine supplementation of 3 grams a day for 10 days. Bio-electric impedance analysis calculates fat mass, total body water, and lean body mass. L-carnitine supplementation led to a significant increase in protein synthesis indicating that the increased dietary fat oxidation in slightly overweight subjects was not accompanied by protein catabolism.

Study # 2

Caffeine, carnitine and choline supplementation of rats decreases body fat and serum leptin concentration as does exercise. J Nutr 2000 Feb;130(2):152-7 The effect of a combination of caffeine, carnitine and choline with or without exercise on changes in body weight, fat pad mass, serum leptin concentration and metabolic indices was determined in 20 male, 7-wk-old Sprague-Dawley rats. They were given free access to a nonpurified diet without or with caffeine, carnitine and choline at concentrations of 0.1, 5 and 11.5 g/kg diet, respectively. In a 2×2 factorial design, one-half of each dietary group was exercised, and the other half was sedentary.

Food intake of the groups was not different, but the body weight was significantly reduced by exercise in both dietary groups. Fat pad weights and total lipids of epididymal, inguinal and perirenal regions significantly reduce with supplements and exercise.


Regardless of exercise, supplements significantly lowered triglycerides in serum but increased levels in skeletal muscle. Supplements and exercise lowered serum leptin concentrations. Serum leptin correlates with body weight, fat pad weight and serum glucose. We conclude that the indices of body fat loss due to dietary supplements with carnitine were similar to those due to mild exercise, and there were no interactive effects of the two variables.

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Carnitine Supplements, Timing and Dosage

L-carnitine is very popular as a stand-alone product, coming in tablet, capsule and liquid forms. Potency will vary anywhere form 250mg to 1000mg on average, with 500mg being  common. Timing is usually product dependent so label reading is a must. As part of formula products, L-carnitine is in a wide array of products. This includes fat loss as well as pre and post workout products. While not a overly common ingredient in “pump” based products, it is in several. Therefore, it does have a hand in the sarcoplasmic hypertrophy concept I’ve mentioned over the course of these guides.

What about timing and dosage? You would usually purchase a formula product for the specific purpose of the product. Therefore, take it as that product suggests. The main formula that’s actually based on carnitine is manufactured by Beverly Nutrition. It’s a combination of 4 different versions of carnitine and claims to have 21 benefits. This is a unique product offering and at this time is pretty much the only one of it’s kind in the marketplace. Finally and as always, careful label reading is a must. Your use of carnitine, especially in fat loss formulas, requires a complete understanding of the product you are purchasing.

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