A Fat Loss Myth or Supplement Staple

Sometimes there is a chemical so central to a process in human physiology that it would defy logic that supplementing the amount or function of the molecule should do anything other than make our health better.

Certainly, the example of creatine monohydrate and the benefits of creatine supplementation on not only muscle mass and strength, but also bone density, neurological function, and other vital processes is an obvious demonstration.

Insofar as fat loss is considered, a number of key molecules have been investigated, such as ketones, beta-2 and beta-3 agonists, specific fatty acids, monoacylglycerides and diacylglycerides, and various hormones.

Yet, in the process of transporting free fatty acids from the cytosol (insides) of a cell to the mitochondria where fatty acids are “burned” to generate energy (ATP) and heat, there is one key molecule— L-carnitine.1

L-carnitine acts like the hostess at a restaurant, escorting you to your table.

Free fatty acids are either taken up from the bloodstream or released from fat stores in metabolically active cells (e.g., skeletal muscle, heart) into the cytosol (cell’s “insides”).

In the absence of L-carnitine, the fatty acids would pretty much stand around or get converted into stored fat.

It is similar to walking into a restaurant when the hostess is on break— you end up standing around in clusters, while some wander to a random table or just leave without “fueling up.”

For purists, L-carnitine’s action relative to beta-oxidation occurs between the outer and inner mitochondrial membrane, but let’s keep it simple for clarity’s sake.



Much like creatine, L-carnitine can be made in many tissues, so healthy people tend to have “enough” L-carnitine. As the “L” form suggests, carnitine is an amino acid, so the body is able to convert precursor amino acids (L-lysine and L-methionine) to L-carnitine in the kidney, liver, and brain.

Related: Capsaicin – A Potent Fat Loss Supplement

However, there are recognized cases of carnitine deficiency. Also, endogenous (in the body) production can only produce a limited amount, so the diet is the primary source of L-carnitine in omnivores, sourced primarily from meat; red meat has the highest concentration, with poultry and fish containing much less.

Vegans are nearly dependent upon endogenous production, accounting for 90 percent of their total L-carnitine. This sounds very similar to creatine’s story, if you are familiar with that. Also, when L-carnitine supplies are low, the kidneys will work harder to pull back any that spills into urine so it is not excreted.1



So, is there any need to supplement L-carnitine? Certainly, there are people who have been identified with L-carnitine deficiency, often due to transporter issues (difficulty getting L-carnitine into cells, or absorbing it from the diet).2

Additionally, newborns and infants may have a greater need for L-carnitine. But what about athletes, or healthy adults looking to lose fat? Initially, the answer appears to be “no.”3 Certainly, L-carnitine has not made a splash as a stand-alone product in the supplement market; it is not a banned substance; and there aren’t even any celebrity endorsers.