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Weight management

L-Carnitine

The shuttle that moves fatty acids into the mitochondria - a classic in energy and fat metabolism.

1 min read 9 sources

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L-Carnitine glass vial with clear solution and the black TPD label on a white podium, next to a large blue 3D molecule model in a bright lab
Approved · since 1985 (levocarnitine)

Summary

At a glance

Sources checked on 26 Oct 2026

Uptake when swallowed
≤18 %

5 to 18 percent reaches the blood as a supplement, from food up to 75 percent3

Carnitine in muscle
+21 %

after 24 weeks, swallowed together with carbohydrate, 14 men1

Fat gained only by controls
+1.8 kg

in 12 weeks, with carnitine fat mass stayed the same, 12 men2

Weight across 43 trials
-1.13 kg

difference to control, only with overweight, body fat percentage unchanged5

Phase 3 with injection or infusion
6 trials

of 14 trials included from ClinicalTrials.gov, as of 26 Oct 20267

  • L-carnitine carries long-chain fatty acids into the mitochondria, where they are burned. The body makes it itself and recovers most of it through the kidneys.3
  • When swallowed as a supplement only 5 to 18 percent is absorbed. As levocarnitine it is an approved drug substance.38
  • Swallowed together with carbohydrate, muscle carnitine rose by 21 percent after 24 weeks. The men used 55 percent less glycogen during light exercise and performed 11 percent more in the test.1
  • In a second study the control group gained 1.8 kg of fat in 12 weeks, the carnitine group did not.2
  • Meta-analyses found 1.1 to 1.3 kg more weight loss, only with overweight and without a change in body fat percentage.45
Profile

Updated June 2026

Class
Amino acid derivative

carnitine

Use
Subcutaneous or intramuscular
Half-life
several hours
Status
Endogenous

IV infusions restricted in sport

Sizes
4 sizes

120mg/ml, 500mg/ml, 30ml/500mg/ml …

Contents 12 sections
  1. At a glance
  2. What is L-Carnitine?
  3. How it works
  4. Use and dosing
  5. What the research shows
  6. Research status
  7. Side effects
  8. Storage
  9. Related compounds
  10. FAQ
  11. Glossary
  12. Sources

What is L-Carnitine?

L-Carnitine is an endogenous amino acid derivative that shuttles fatty acids into the mitochondria, where they are burned for energy. In research and fitness contexts the injectable form is used for fat metabolism and endurance.

This information is for research and educational purposes only. No medical advice.

Comparison

L-carnitine alone and in blends

Components according to the TPD lexicon. MIC stands for methionine, inositol and choline. Tap a card to open its entry.

Single substance L-Carnitine MIC L-carnitine B12 B complex 1 of 4 components
MIC plus L-carnitine Lipo-C FOCUS MIC L-carnitine B12 B complex 2 of 4 components Highest concentration Lipo-C FAT BLASTER MIC L-carnitine B12 B complex 3 of 4 components Amino acid-vitamin blend Lipo-C 120mg MIC L-carnitine B12 B complex 2 of 4 components With extended B complex Lipo-B 216mg MIC L-carnitine B12 B complex 3 of 4 components Lipotropic blend Lipo Mino Mix MIC L-carnitine B12 B complex 1 of 4 components

Simplified: the amounts per component differ. More components do not automatically mean more effect.

How it works

Without carnitine, long-chain fatty acids cannot cross the inner mitochondrial membrane. L-Carnitine is the shuttle for that - more available carnitine can support fatty acid oxidation. Injected, it bypasses the limited oral uptake.

Where it acts

Where L-carnitine acts

Tap a point or a card. Values from human studies, mostly swallowed.

  1. Skeletal muscle

    21 percent more carnitine after 24 weeks, less glycogen use during light exercise1

    L-carnitine
  2. Fat tissue

    No fat gain in 12 weeks, the control group gained 1.8 kg of fat2

    L-carnitine
  3. Heart muscle

    Heart and skeletal muscle form the carnitine store that fills most slowly3

    L-carnitine
  4. Kidney

    Recovers most carnitine, any excess goes into the urine3

    L-carnitine
  5. Gut

    When swallowed as a supplement only 5 to 18 percent is absorbed3

    L-carnitine

Targets in the ChEMBL database9

Compound Levocarnitin (CHEMBL1149): three recorded mechanisms, type of action on each card.

Carnitine transporter OCTN2
Gene
SLC22A5
UniProt
O76082
ChEMBL
CHEMBL2073693
Action
Transporter, brings carnitine into the cell together with sodium
Carnitine palmitoyltransferase 1, muscle form
Gene
CPT1B
UniProt
Q92523
ChEMBL
CHEMBL2216739
Action
Enzyme, attaches long-chain fatty acids to carnitine so they can enter the mitochondria
Carnitine palmitoyltransferase 2
Gene
CPT2
UniProt
P23786
ChEMBL
CHEMBL3238
Action
Enzyme in the mitochondria, releases the fatty acid from carnitine again for burning
Glass mitochondrion with a double envelope, a golden chain of fatty acids is guided through the membrane into the interior by blue molecule models
Without carnitine long-chain fatty acids cannot cross the inner membrane. Symbolic image.

Use and dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts
Glass vial with clear liquid, a blue cap and a black TPD label for L-Carnitine, a disposable syringe beside it
Ready-made solution, subcutaneous or intramuscular. Symbolic image.

What the research shows

Wall et al. (J Physiol, 2011) showed that chronic L-carnitine intake together with carbohydrate raises muscle carnitine content and alters muscle metabolism during exercise - less glycogen use at moderate intensity. Data on pure fat-loss effects in humans are mixed.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Muscle metabolism after 24 weeks1

Change in percent, 14 healthy men

Carnitine in muscle1 compared with the start
Control (carbohydrate only) 0% unchanged
Carnitine with carbohydrate +21%
Output in the 30-minute test1 compared with the start
Control (carbohydrate only) 0% no change
Carnitine with carbohydrate +11%
Glycogen use during light exercise1 compared with control
Carnitine with carbohydrate -55%
Muscle lactate during hard exercise1 compared with control
Carnitine with carbohydrate -44%

Carnitine was swallowed here together with carbohydrate meant to raise insulin. All effects only appeared after 24 weeks. There is no such study with injection under the skin.

Weight and fat after 12 weeks2

Change in kg, 6 men per group

Body weight2
Control (carbohydrate only) +1.9 kg
Carnitine with carbohydrate 0.0 kg unchanged
Fat mass (DXA)2
Control (carbohydrate only) +1.8 kg
Carnitine with carbohydrate 0.0 kg unchanged

In the carnitine group muscle carnitine rose by 20 percent and energy expenditure by 6 percent. The control group got the carbohydrate only and gained weight from it. Very small study.

Weight loss in meta-analyses45

Difference to the comparison group in kg

Weight, 9 trials4 911 people
With carnitine, difference to control -1.33 kg
Weight, 43 trials5 effect only with overweight
With carnitine, difference to control -1.13 kg
Fat mass, 43 trials5 body fat percentage and waist unchanged
With carnitine, difference to control -1.16 kg

Small effects. In the first analysis the weight loss became smaller with longer duration. In dialysis patients body measures did not change.

Glass mitochondrion model on a wooden base on a bright table, next to a skipping rope and a green plant in front of a large window
Human studies mostly gave carnitine by mouth. Symbolic image.

Research status

Where the research stands

Registered trials in which L-carnitine was given by injection or infusion. Most concern dialysis, the heart and intensive care. As of 26 Oct 2026. 7

  1. Preclinical Endogenous substance, uptake and excretion well described
  2. Phase 1 no registered trial
  3. Phase 2 2 trials, 0 completed, 1 stopped early
  4. Phase 3 6 trials, 4 completed, 1 stopped early
  5. Approval since 1985 (levocarnitine)
1,189 participants in phase 3 Planned figures for running trials Approved as the drug substance levocarnitine, according to ChEMBL first in 1985. It is used for carnitine deficiency, for example during dialysis.8
Show all 14 trials on a timelineHide timeline 9 completed 2 running 3 stopped early 0 with results
Phase 2
Phase 3
Phase 4
Without phase

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 26 Oct 2026, grey = stopped early.

Side effects

  • Overall very well tolerated.
  • Occasional fishy body odor at high doses (TMAO formation).
  • Mild gastrointestinal discomfort possible.

Storage

Store at room temperature, protected from light - no fridge needed. Out of reach of children.

Related

Related compounds

Blends with L-Carnitine or a different path: all in the TPD lexicon.

L-Carnitine
Lipo-C FOCUS Contains L-carnitine plus MIC Lipo-C FAT BLASTER Contains L-carnitine plus MIC and B12 Lipo-C 120mg Lipotropic blend without L-carnitine Lipo-B 216mg Lipotropic blend with B vitamins NAD+ Inject Coenzyme in mitochondrial energy metabolism MOTS-c Peptide from the mitochondria B12 Vitamin for energy metabolism

FAQ

Common questions about L-Carnitine

Short answers, each backed by the sources below.

What does L-carnitine do in the body?

It carries fatty acids into the mitochondria, where they are burned. The body gets carnitine from food, makes it itself and recovers most of it through the kidneys. Heart and skeletal muscle are the store that fills most slowly.3

Why inject instead of swallow?

From supplements the gut absorbs only 5 to 18 percent, from normal food up to 75 percent. Injected, this bottleneck is gone. Whether that brings more for fat loss is not shown by the studies here, they gave carnitine by mouth.312

Does more carnitine reach the muscle?

Only under certain conditions. Together with carbohydrate that raises insulin, muscle carnitine rose by 21 percent after 24 weeks. The men then used 55 percent less glycogen during light exercise and performed 11 percent more in the test. A second study found 20 percent more muscle carnitine after 12 weeks.12

Does L-carnitine help with weight loss?

A little and only with overweight. A meta-analysis of 9 trials with 911 people found 1.33 kg more weight loss, one of 43 trials found 1.13 kg less weight and 1.16 kg less fat mass. Body fat percentage and waist did not change, with longer duration the effect became smaller.45

Is L-carnitine approved?

As the drug substance levocarnitine, yes, according to ChEMBL first in 1985. It is used for carnitine deficiency. During dialysis carnitine is lost through the dialyser, so some patients receive it there.83

What does L-carnitine have to do with TMAO?

Gut bacteria turn swallowed carnitine into TMA, which becomes TMAO. In mice this promoted deposits in the vessels. In 2,595 people a high carnitine level was linked to more cardiovascular events when TMAO was also high. The study looked at swallowed carnitine.6

Where is injected L-carnitine studied?

The registry lists the 14 trials with injection or infusion included here, 6 of them in phase 3. They are mainly about dialysis, heart failure, preterm infants and intensive care, not about fat loss in healthy people.7

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Bioavailability
The share of a substance that actually reaches the blood. For swallowed carnitine from supplements it is 5 to 18 percent.
CPT1
An enzyme that attaches fatty acids to carnitine. Only then can they enter the mitochondria.
Dialysis
Blood cleaning in kidney failure. Carnitine is also lost in the process.
Fatty acid oxidation
Breakdown of fatty acids in the mitochondria to make energy, also called beta-oxidation.
Glycogen
The storage form of sugar in muscle and liver. Less glycogen use means the muscle uses more fat.
Inner mitochondrial membrane
Tight envelope around the inside of the mitochondrion. Long-chain fatty acids only pass with carnitine.
Levocarnitine
The name of L-carnitine as a drug substance.
Meta-analysis
A combined analysis of several studies on the same question. It is only as good as the studies it includes.
Mitochondria
The power plants of the cell. Here energy is made from fat and sugar.
TMAO
Trimethylamine N-oxide. Formed when gut bacteria break carnitine or choline down to TMA, which is then converted further.

Evidence

Sources

Show all 9 sourcesHide sources 6 Studies1 Trial registry2 Database checked 26 Oct 2026

Studies

  1. Carnitine with carbohydrate over 24 weeks, muscle metabolism

    Wall et al., Journal of Physiology, 2011

    DOI 10.1113/jphysiol.2010.201343 PMID 21224234
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. Muscle carnitine, energy expenditure and body fat over 12 weeks

    Stephens et al., Journal of Physiology, 2013

    DOI 10.1113/jphysiol.2013.255364 PMID 23818692
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Uptake, distribution and excretion of L-carnitine (review)

    Evans und Fornasini, Clinical Pharmacokinetics, 2003

    DOI 10.2165/00003088-200342110-00002 PMID 12908852
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Carnitine and weight loss, meta-analysis of 9 trials

    Pooyandjoo et al., Obesity Reviews, 2016

    DOI 10.1111/obr.12436 PMID 27335245
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. Carnitine and body weight, meta-analysis of 43 trials

    Askarpour et al., Pharmacological Research, 2020

    DOI 10.1016/j.phrs.2019.104554 PMID 31743774
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  6. Gut bacteria turn carnitine into TMAO (humans and mice)

    Koeth et al., Nature Medicine, 2013

    DOI 10.1038/nm.3145 PMID 23563705
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Trials with L-carnitine on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Levocarnitine in ChEMBL (phase 4, approved 1985)

    ChEMBL, EMBL-EBI (CHEMBL1149)

    Checked 26 Oct 2026 via ChEMBL API
  2. OCTN2, CPT1B and CPT2 in UniProt

    UniProt (O76082, Q92523, P23786), Target-IDs aus ChEMBL

    Checked 26 Oct 2026 via UniProt REST, ChEMBL API

In the shop

L-Carnitine in the catalog

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