L-Carnitine
L-Carnitine is a naturally occurring amino-acid derivative that shuttles long-chain fatty acids into the mitochondria to be burned for energy. In injectable form it is used in research and aesthetic settings to support fat metabolism, exercise energy, and recovery.
Best for
Individuals pursuing body-recomposition or endurance goals who want to support mitochondrial fatty-acid oxidation alongside diet and training.
What to expect
No acute felt effect; any metabolic or endurance benefit accrues gradually over weeks of consistent use combined with exercise.
Pairs with
Often paired with a caloric deficit and regular cardio/resistance training; sometimes stacked with GLP-1 agents or other metabolic compounds, though it is frequently run standalone.
Typically administered intramuscularly or subcutaneously at roughly 200-600 mg per injection, 2-3 times per week; conservative research protocols start at the low end (200 mg) and titrate based on tolerance.
- How often
- 3×/week
- When
- Morning
- Route
- Intramuscular
- Vial & water
- 1,000 mg vial in 1 mL = 1,000 mg/mL · 200 mg = 20 units on a U-100 syringe
- Cycle
- Commonly run continuously alongside diet and training; some protocols cycle 8-12 weeks on with breaks.
The same numbers the goodtides app and the Dose Calc use — a research reference, not a prescription. Responses are individual; research protocols start at the low end.
L-Carnitine (beta-hydroxy-gamma-trimethylaminobutyrate) is a small quaternary-ammonium compound synthesized in the body from the amino acids lysine and methionine, and also obtained from red meat and dairy.
Injectable L-carnitine is not an FDA-approved weight-loss therapy; the injectable formulations marketed for aesthetics and body composition are sold for research use only and have not been reviewed for that purpose.
Its central physiological role is as an obligatory cofactor in the carnitine shuttle: it binds long-chain fatty acids at the outer mitochondrial membrane via carnitine palmitoyltransferase-1, transports them across the inner membrane, and releases them into the matrix for beta-oxidation, the primary pathway by which fat is converted to ATP. By facilitating this transport, L-carnitine influences the balance between fat and carbohydrate use for fuel.
Clinical research firmly supports supplementation in genuine carnitine-deficiency states (certain metabolic disorders, dialysis patients, some cardiac conditions), where it has established therapeutic value. In healthy, non-deficient individuals the evidence for meaningful fat loss or performance enhancement is mixed and generally modest, and injectable 'fat-burning' claims outpace the controlled data.
Anyone considering it should do so under qualified physician guidance, particularly given individual variation in baseline carnitine status. This information is educational and is not medical advice.
References3
- Longo N et al. - Carnitine transport and fatty acid oxidation (Biochim Biophys Acta)
- Pooyandjoo M et al. - The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials (Obes Rev)
- Rebouche CJ - Kinetics, pharmacokinetics, and regulation of L-carnitine and acetyl-L-carnitine metabolism (Ann N Y Acad Sci)
Log every dose, count every vial, and verify your batches — free in the goodtides app.
This page is educational reference material about compounds studied in research settings. It is not medical advice, and nothing here is a recommendation to buy, possess, or use any compound. Research findings described are from published literature; individual compounds may not be approved for human use. Talk to a licensed clinician about anything that affects your health.