How does L-Carnitine work to help speed weight loss? What evidence is there that it works?

In a study of 18 overweight subjects, carnitine greatly increased weight loss. The subjects were split into two groups of 9. For 12 weeks, both groups ate a healthy diet and performed moderate exercise. One group was given 2000 mg of carnitine, and the other a placebo. In the placebo group, the average weight loss after 12 weeks was one pound. In the carnitine group, weight loss averaged 11 pounds. That’s an eleven-fold increase in weight loss, simply by increasing carnitine levels. Body fat percentage levels also decreased markedly in the carnitine group.

However, not everyone will experience such a dramatic effect of weight loss with carnitine. In a recent study, individuals taking carnitine for 8 weeks did not experience increased weight loss. So, how does one know if it is even worth trying this supplement. Well, in my experience, individuals following a reduced carbohydrate diet, and incorporating aerobics and strength training, usually find it easier to lose weight while taking carnitine on an empty stomach, 30 minutes before breakfast, when compared to those following the same protocol minus L-carnitine.

We hope all is well with you and that you find this information useful.

If you want to learn more about increasing or decreasing metabolism, losing or gaining weight, and how to use natural approaches to achieve your goals, please have a look at the new book!


Articles of interest:

  • Rebouche CJ, Paulson DJ. Carnitine Metabolism and Function in Humans. Ann Rev Nutr 1986; 6:41-66.
  • Avogaro P, Bon GB, Cazzolato G, Rorai E. Acute Effects of L-carnitine on FFA and Beta-OH-Butyrate in Man. Pharmacol Res Commun 1981; 13 (5): 443-50.
  • Int J Sport Nutr Exerc Metab 2000 Jun;10(2):199-207

Good Luck!

Robert L. Pastore, Ph.D., CNC, CN
Senior Nutritionist at

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  • Don

    Could you please provide more details on this study? What institute carried it out? What year was conducted? Do you have a link to the full study?

  • Dr. K.L. Planken

    Interesting story about L-Carnitine. I looked up the references and I think you should also list the title of the third article: “L-Carnitine supplementation combined with aerobic training DOES NOT promote weight loss in moderately obese women”.

  • amanda

    Thanks for the tip, i lose 10 lbs in 7 days, followed the meal plan given by the Cosmo Body, im currently taking Cosmo Body L- Carnitine Supplement

  • Matin

    I started taking alli 3 days ago and today was the first time I noticed anything different happening with my body. First, I had to go to the bathroom really bad after my breakfast+alli and there were floating drops of fat. Then, I cannot stop passing really nasty smelling gas, and I’m continuously afraid to pass gas for fear I will pass something more. However, seeing the fat come out kind of makes me happy. Fat is good for you, but I don’t mind sending a bit of it down the shute. This experiment is pretty cool so far. And it does make me watch what I eat a little more.

    • john

      You are probably taken way in excess. I have never had any side effect.

  • jason

    Matin, if you’re shitting or pissing fat then you should see a doctor. That is NOT a healthy result for any kind of supplement.

  • I WOULD NOT RECOMMEND anything that CAUSES MALABSORPTION which can quickly lead to MALNUTRITION. This medication is designed to prevent absorption of nutrients (fat specifically in this case) but it also can interfere with fat soluble vitamin status. Drug induced nutrient depletions is a serious issue to be considered. Also, instead of trying to not absorb fat, the best thing to do is find out which fats are healthiest for us and eat them in moderation!

  • angie


    About the Alli that Matin takes, fat if absorbed in your body and is then released by dumping. It’s orange and it stinks.

  • It is a supplement that should only be taken if you are in perfect health due to its contraindications and, preferably even if you are in perfect health, only after seeking advice from your physician.

  • sarah

    it only has been a week of me taking godex, i lost 6 lbs no side effects so far. thank you for sharing your knowledge that i should take it 30 mins before meal. my doctor didnot instruct me about that

  • jen

    Should i be taking the whole 2g of l-carnitine in just 1 dose beforebreakfast? or i can divide it in 2 doses? Thanks.

  • Eric

    Has anyone here tried using carnitine for weight loss?

  • Al

    L-carnatine will not help with weightloss in moderatly obese women if those women have either insulin resistance, hyper thoroid or PCOSmainly with any of those 3 female hormones are thrown “out of wack”….best way to lose weight in moderately obese women with any of the above 3 problems mentioned should take metformin bewarned tho it will increase your fertility

  • Andrew

    L-Carnitine helps if you are on a fat burning diet,meaning lower carbs than normal,same amount of protein and non saturated fat like oil,omega 3 etc.
    500mg-1000mg prior to workout helps burning a bit more fat.
    No supplement can be compared to healthy nutrition diet though.If you do not eat properly do not use it.

  • duane

    i have table form 45 capsules 499mg How do I take them and how many a day for fat loss and I train at the gym.

  • Jason and Matin, while taking Allli you will notice fat/oil floating on the top of the water with your shit.. however, this is normal and if anyone has looked up or spoken to a doctor about this they will tell you that you will or may need to wear a pantie liner to protect yourself if you think you are going to have gas it may be poop. they also suggest to take extra clothing to work and some in your car just in the event you poop your pants. so before telling someone they are full of shit.. think twice do your research and by all means if you are a doctor go back to school

  • Rosa

    When is the best time to take L-Carnitine. Before workout? Before meal? At bedtime? Empty stomach?? Please advise.

  • adrianjt

    i would greatly appreciate if someone could explain the differences between Acetyl L-Carnitine & L-Carnitine Fumarate.
    I wish to both reduce my weight & and fell less lethargic

    thanks in advance

  • jenny

    Can I take Acetyl l carnitine with tumeric?

  • MelissaO

    I’ve been taking L-Carnitine for about 6 weeks and can see a HUGE difference in my energy level and i’ve gone from a size 6/8 to a 4. However, I also do a 30-40 minute cardio workout either internal training (walk/run) or a brisk walk 5 to 6 days a week. I always through in some stretching and a quick abb workout and it TRULY WORKS! Don’t give up on this product because it does work if your consistant and you workout/eat well. 😉 Best of Luck everyone!

  • Deena

    MelissaO, how much are you taking, what form, and when? I am curious because I just started a few days ago. I am on Atkins, exercise almost every day, doing an hour on an inclined treadmill, drink only water and started taking the L-Carnitine. I am taking the liquid form,1100mg, twice a day, one hour before eating or workouts. Although it’s only been 4days, I am anxious to see some results. I read that for weight loss 3,000-5,000 mg should be taken daily. I am happy to hear that it has worked for you and am hoping it will for me too!



  • andy

    Can we hear from few people that have taken it for over 3 months? Can you please report how it worked for you? Did you lose weight? If so how much?

  • anel

    plz i would like to know what exactly should eat with the L’Carnitine?and 30min before breakfast and lunch but how about the 30 minutes of tredmile when it should take place?plz really would like to know.
    its been 6 days and no difference, seems there is sthg wrong with my scedule.

  • Barry

    I am a Doctor who works with lots of weight loss patients. I sometimes giver patients L-carnitine intramuscular injections and the results are good. However, I have not personally seen and significant results with oral supplementation. It may have to do with dose/absorption levels. The injections have been used in race horses and race dogs for a long time. I have found that whatever they use tend to be very effective supplements.

  • Richi

    Hi everyone I just came back from a long trip and put on some weight. Considering taking L-carnitine to complement my workout routine. Any advise on brands or other supplements that may help enhance my weight loss? Thanks!


    I’ve been taking L-C for about a month now, and I feel great. It’s also helped with my sex drive – I wake up almost every morning now with a huge hard-on. I’ve been having to see whores and skanks to satisfy my crazy-awesome sex drive. It’s almost like I’m on Viagra or something, I can go for hours now 🙂 Anyway, thats the only side-affect I’ve had, and its been a really pleasant experience 😉 Lost 15 pounds so far, btw.

  • jasmine

    hey i’am jasmine i’am fat and i want lose some pounds and they tell me to use l-C but i practice sports and we can’t doping so i wanna ask if the is do-page in l-C plz answer me because i wanna lose some pounds in this mounth

  • JennsaWinner

    Ok I’m hypothyroid and pcos, I take synthyroid and cytomel. I discovered Carni Fuel by twin labs back when my thyroid crashed. I took it daily, once or twice a day. Ate low carb high protein. Minimum exercise… I lost 25-30lbs fast with this. I swear by L-Carnitine I am always sharing the info with ppl because its natural, it works if you do it right and have discipline with your meals. Increase water so it can do its job in your mitochodria inside your cells. If you don’t eat clean and lean max your water its not going to work. It’s a lipotropic process, and needs adequate h20 to transport the long fatty acid chains to the mitochondria to be burned then passed via sweat, urine, or pooptypoop. Someone asked the difference between the different types…

    L-Acytle Carnitine breaks the blood barrier of the brain and supports more cognitive, and heart support. Not metabolic like plain L-Carnitine that’s for weightloss, endurance, cutting up, leaning out, increasing vascularity, reducing plaques ect… Very amazing amino acid I must say. I will take it for life for plaque and fat prevention. I have plaque related diseases in my family I fight not to get with this stuff. Stay away from D-Carnitine its toxic to us and no good. The only one you want is pure L-Carnitine and some times it may say L-Carnitine-Tartrate which is the purest form. I stack CLA, Carni Fuel, Betagen w/ Revigor, Jay Robbs egg protein, Spirulina powder, Cinnamon, Folic acid, Chromium picolanate, Astaxanthan, Krill oil, and Opti Women multi… They have men’s too 🙂 f**king fantastic energy and perfect stack/ regimine… I don’t work out much but I’m already built, just retained it from sports and rotc… Honesty Carni Fuel gives best results, second would be Cuts ll… Or combination… Goodluck hope this helped. I study preventative medicine, and health. Sorry for my typos dam cell.

  • JennsaWinner

    Jasmine, you can’t dope a naturally occuring amino acid you get from your diet already. It’s is what transports fat into your cells for them to be burned. I don’t just take Carnitine to keep my weight down. I take it for longevity… You have been getting it since the day you were created. It’s the building blocks of our DNA… Everything I listed in my last post is all natural and legal. None of it is concidered dopeable LOL

  • L-Carnitine 500 twice a day did not work for me … but then I do have a thyroid disorder… slow.. and it is very costly… I tryinbg CLA and Raspberry Ketone… see how that works…

  • Jerry

    Oh goodie, I get to review this stuff called Lcarnitine. ELvis Presley would have loved this puppy. I took this 2 years ago, not the 2000mg which is suggested, more like 500 mg morning before jogging & 500 mg at night. My weight was between 290 & 300 when I started, I only did a month supply just to kick start my metabolism. 3 months later, my weight was 250 pounds, a whooping 50 pounds lost. remember, I only took the product for one month. I’m not a big fan of fat burners or crazy products that make promises. The body does fine without these, we just need to give it a boost sometimes. Once your body gets use to doing something such as burn fat, it will keep doing it rather you take some product to get there or not. Take a person who reaches a point where the body no longer is effective at burning fat, a slow down if you will.. no problem, just give the body a short term kick in the butt, you do not need to live on any product therefore stay on it till the results come then get off of it & do it natural. You will find, the body will have no problem in doing off the product what it does on the product once the body has had the time to adjust to do what we would like such as burn fat. If you wanna be lazy by gosh, your teaching the body not to burn fat & surly it will do just that given the time to adjust to that life style. As for Lcarnitine, give it a try. In doing so, it works best when blood sugar is low, you can still eat normal just make sure 2 hours before you exercise the meal is no carbs, extra protein, healthy fats. Also take a vitamins, calcium, magnesium, zinc & some amino’s to provide the body what it needs prior to a wrk out. My diet was average, nothing fancy, no calorie counting, 2000 calories a day. For me my objective was not to burn fat throughout the day but to burn fat in my workouts which worked well for me. There is no reason to starve the body.

  • Deborah

    After being on Depakote for 17 years, I had 10 dietary deficiencies (and arthritis from high calcium.) L-carnatine was one of them. If I was epileptic, it wouldn’t be safe to augment it, but I’m not. It has made a world of difference in my life. I’m not yet losing weight (I have to increase everything slowly), but good things are happening. It’s nice to know I’ll be able to weight again soon, as well as walk right and many other things. (The arthritis in my legs is long gone.)

  • Simon

    I have used L-Carnitine for 4 months. I was originally introduced to the product as a post workout energy booster. It worked, I take it before my workout because it gives energy. Has it helped with weight loss, Yes but I think it was because it has raised my energy levels. I have lost over 50 punds in the last 7 months BUT that was a mixture of things, Daily workout ( Cardio every day weight training 3 days a week.) New Diet of mostly fish and chicken on occasion and Vitamins. I used the liuid version of L-Carnitine but next week I am going to try the tablets. One thing to point out, the effects of additional energy were more noticable when I started, Not as much now.