# L-Carnitine

> L-Carnitine is a naturally occurring amino-acid derivative that transports long-chain fatty acids into mitochondria for beta-oxidation. It is one of the most extensively studied nutritional compounds related to fat metabolism and exercise performance. Meta-analyses of oral supplementation report modest average reductions in body weight and fat mass, generally smaller in magnitude than pharmaceutical weight-management agents. It is widely available as an over-the-counter supplement rather than a prescription therapy.

- URL: https://www.lifeconverted.com/peptides/l-carnitine
- Also known as: Levocarnitine
- Primary category: Weight Management
- Effectiveness rank: #14 in Weight Management; #6 in Metabolic
- Evidence level: Well studied
- Route: Oral (Intravenous and intramuscular forms are used in some clinical and research settings, but oral supplementation is the most common route for weight-related use.)
- Dose range: 500-2,000 mg
- Dose tiers: low 500 mg; moderate 1000 mg; high 2000 mg
- Half-life: Approximately 15 hours for oral elimination half-life, based on published pharmacokinetic studies
- Timing: ~30 min before exercise
- Cycle: Commonly used continuously as a daily supplement on, No established off-cycle is required for typical supplemental doses off
- Storage: Store at room temperature in a sealed container, away from moisture and direct light, per product labeling.

## Mechanism of action

L-Carnitine shuttles activated long-chain fatty acids across the inner mitochondrial membrane via the carnitine-acylcarnitine translocase system, a required step for mitochondrial beta-oxidation of fat. Adequate carnitine availability is proposed to support fat-based energy metabolism, particularly during exercise, though endogenous synthesis and dietary intake are typically sufficient in most healthy individuals, which may limit the additional benefit of supplementation.

## Reported benefits

- Modest reductions in body weight and fat mass reported in meta-analyses
- May support exercise recovery and reduce exercise-induced muscle damage
- Well-characterized long-term safety profile
- Widely available and inexpensive compared with pharmaceutical alternatives

## Reported side effects

- Gastrointestinal upset, including nausea and diarrhea, at higher oral doses
- A fishy body odor has been reported, related to gut microbial metabolism of carnitine
- Rare reports of interactions with anticoagulant medications
- Effects on weight are generally modest and may not be noticeable for all users

## Common protocols

- Daily oral supplementation, often taken with a meal containing carbohydrate to support absorption
- Sometimes timed before exercise in research on performance-related outcomes

## Stacking notes

Sometimes combined with exercise or other metabolic supplements; evidence for added benefit from stacking is limited.

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