Spending tons of money on supplements is great, and if you agree with that statement, then this article may not be for you. You see, I prefer to spend as little as possible on supplements, so the money I do spend is definitely going to be on a supplement that is going to benefit me a lot. In the past L-Carnitine has been on the receiving end of quite a bit of poo-pooing by those who tried it and didn’t immediately turn into a fitness model. I believe these folks, and their claim that L-carnitine did not work for them the way they expected, but the same can be said for jumping into a lamborgini and not being able to drive stick. A great product, not used properly, makes for crappy results.
Approximately 95% of the body’s carnitine is located in skeletal muscle. Carnitine is a substrate for an enzyme which is a rate limiting step in fatty acid oxidation in the mitochondria. A recent study has shown that when total muscle carnitine content is increased, body fat mass accrual associated with carbohydrate supplementation was prevented. In the study 2 groups of healthy males were given 80g of carbohydrates (control group) or 80g carbohydrates with 1.36g of L-carnitine (carnitine group). Each group supplemented 2 times a day for 12 weeks. The researchers concluded that not only was carnitine responsible for preventing fat gain in the carnitine group vs. the control group, but also that the prevention of fat gain was associated with an upregulation of genes and gene networks relating to fuel metabolism. They also found an increase in energy expenditure and fat oxidation during low intensity exercise (<50% of max oxygen consumption). In this particular study, after 12 weeks of L-carnitine and carbohydrate supplementation, muscle total carnitine increased by 20%, Long-chain acyl-CoA increased by 200%, and whole-body energy expenditure increased by 6%1.
Here are some things that you can do to take advantage of L-carnitine:
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The doses used in the studies averages about 3g L-carnitine per day.
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The studies were conducted over 12-24 week periods. So be patient.
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Take your L-carnitine with carbohydrates. Carbohydrates spike insulin, and insulin as a nutrient driver helps load the muscle with carnitine at a faster rate than ingestion of L-carnitine alone2. If you use an intra-workout drink, that would be a pretty good opportunity to take advantage of increased carnitine uptake by spiked insulin levels.
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Weight train. Why not burn a higher percentage of fat during your training, and retain a fuller look to the muscle by sparing muscle glycogen?
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Cardio. I realize the huge debate between steady state and HIIT cardio. Consider for a second that if you do your HIIT first and then just cruise at a nice slower steady pace for a little while after, you could take advantage of the EPOC from the HIIT, and also the higher amount of fat oxidized while you walk due to your new friend L-Carnitine.
-Brad Hull
References:
1.Stephens, F. B., Wall, B. T., Marimuthu, K., Shannon, C. E., Constantin-Teodosiu, D., Macdonald, I. A., & Greenhaff, P. L. (2013). Skeletal muscle carnitine loading increases energy expenditure, modulates fuel metabolism gene networks and prevents body fat accumulation in humans. , (Pt 18), 4655–
2.Wall, B. T., Stephens, F. B., Constantin-Teodosiu, D., Marimuthu, K., Macdonald, I. A., & Greenhaff, P. L. (2011). Chronic oral ingestion of l-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. , (Pt 4), 963–
Dylan Vondra says
I was curious on your thoughts with injectable l carnitine ? John meadows is a big believer in it and isnt to fond of the oral version. I was curious as to your opinion between the two pros cons etc?
Justin Harris says
Oral is pretty much worthless IMO. You’d just have to take too much.
Injectable works well–but the number and volume of injections is high enough that it becomes a burden to keep them up (especially when considering all the other things you’re likely to be doing/taking during contest prep). The biggest issue I’ve seen with injectable L-carnitine is that people get tired of the daily injection volume and quit taking it after a few weeks.
bradley hull says
Agreed. The injectable kind is where its at, and it works…. but the frequency of injections is a pain in the ass, or leg, etc…