From the Guidelines
The recommended dose of L-carnitine for weight loss is not supported by strong evidence, and its use should be approached with caution due to potential side effects, particularly at high doses of approximately 3 g/day, which can cause nausea, vomiting, abdominal cramps, diarrhea, and a “fishy” body odor, as noted in the espen micronutrient guideline 1. When considering L-carnitine supplementation for weight loss, it's essential to weigh the potential benefits against the risks. While some studies suggest that L-carnitine may help with weight loss by increasing fat oxidation, the evidence is not conclusive, and the optimal dosage is not well established.
- Key considerations for L-carnitine supplementation include:
- Starting with a low dose, such as 500 mg per day, to minimize side effects
- Gradually increasing the dose if needed and under medical supervision
- Combining L-carnitine supplementation with regular exercise and a calorie-controlled diet for optimal results
- Being aware of potential interactions with certain medications or underlying health conditions, such as kidney or liver disease, or seizure disorders, as highlighted in the espen micronutrient guideline 1
- It's also important to note that L-carnitine supplements may not be effective for weight loss in all individuals, and their use should be carefully evaluated on a case-by-case basis, considering the potential for side effects, such as muscle weakness in uremic patients and seizures in those with seizure disorders, as reported in the context of a metabolic study 1. Ultimately, the decision to use L-carnitine for weight loss should be made in consultation with a healthcare provider, taking into account individual health status, medical history, and potential risks and benefits, as the espen micronutrient guideline suggests 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Levocarnitine Oral Solution USP. For oral use only. Not for parenteral use. Adults: The recommended dosage of levocarnitine is 1 to 3 g/day for a 50 kg subject, which is equivalent to 10 to 30 mL/day of Levocarnitine Oral Solution USP. The FDA drug label does not answer the question.
From the Research
L-Carnitine and Weight Loss
- L-Carnitine is a molecule involved in fatty acid metabolism, transporting fatty acid chains into the mitochondrial matrix to break down fat and produce energy 2.
- Some studies suggest that L-Carnitine may have beneficial effects on weight loss, although the evidence is not conclusive 2, 3.
Recommended Dose for Weight Loss
- A systematic review and meta-analysis of 37 randomized controlled trials found that L-Carnitine supplementation significantly decreased body weight, with a non-linear dose-response association suggesting that 2000mg per day may provide the maximum effect in adults 3.
- Another study found that 2g of L-Carnitine twice daily did not promote weight loss in moderately obese women, casting doubt on the efficacy of L-Carnitine supplementation for weight loss 4.
Effects of L-Carnitine on Exercise Performance
- A systematic review found that L-Carnitine supplementation improved high-intensity exercise performance, with effective doses ranging from 3 to 4g ingested 60-90 minutes before testing or 2-2.72g/day for 9-24 weeks 5.
- However, L-Carnitine supplementation did not improve moderate exercise performance, and its effects on weight loss and body composition are still unclear 5, 6.
Limitations and Future Research
- More research is needed to fully understand the effects of L-Carnitine on weight loss and body composition, as well as its potential interactions with other supplements and exercise regimes 2, 3.
- The optimal dose and duration of L-Carnitine supplementation for weight loss and exercise performance are still unknown, and further studies are required to determine its efficacy and safety in different populations 4, 5.