From the Guidelines
Liquid carnitine is not a recommended supplement for weight loss due to its minimal benefits and potential side effects. The most recent and highest quality study, published in 2023 in the journal Diabetes Care 1, found that there is no clear evidence that nutrition supplements, including carnitine, are effective for weight loss. This study suggests that more effective weight loss approaches include caloric deficit through diet modification, regular physical activity, adequate sleep, and stress management.
Key Points to Consider
- Carnitine is a compound that helps transport fatty acids into cells' mitochondria for energy production, but research shows minimal benefits for weight loss in most healthy individuals.
- Typical supplements contain 500-2000 mg of L-carnitine per day, but even at these doses, studies indicate only modest effects on weight loss—typically less than 2 pounds more than placebo groups.
- The body naturally produces sufficient carnitine, and additional supplementation doesn't substantially increase fat metabolism in individuals with normal carnitine levels.
- More effective weight loss approaches include:
- Caloric deficit through diet modification
- Regular physical activity
- Adequate sleep
- Stress management
- If considering carnitine supplements, be aware that they may cause side effects like nausea, vomiting, stomach discomfort, and a fishy body odor, particularly at higher doses.
Evidence-Based Recommendation
Based on the most recent and highest quality study 1, liquid carnitine is not a recommended supplement for weight loss. Instead, focus on evidence-based weight loss approaches that prioritize lifestyle modifications, such as diet, physical activity, sleep, and stress management.
From the FDA Drug Label
It has been shown to facilitate long-chain fatty acid entry into cellular mitochondria, thereby delivering substrate for oxidation and subsequent energy production. The FDA drug label does not answer the question.
From the Research
Effectiveness of Liquid Carnitine for Weight Loss
- Liquid carnitine has been studied for its potential effects on weight loss, with some studies suggesting it may be effective in reducing body weight and body mass index (BMI) 2, 3.
- A systematic review and meta-analysis of 37 randomized controlled trials found that l-carnitine supplementation significantly decreased body weight, BMI, and fat mass, especially among adults with overweight or obesity 2.
- Another study found that subjects who received carnitine lost significantly more weight and showed a decrease in BMI compared to the control group 3.
- However, the magnitude of weight loss resulting from carnitine supplementation may decrease over time 3.
Mechanism of Action
- Carnitine plays a key role in the transportation of fatty acids into the mitochondria for oxidation, which may contribute to its potential weight loss effects 4, 5.
- L-carnitine may also help improve insulin sensitivity and reduce liver fat, which could be beneficial for weight loss 5, 6.
Dosage and Efficacy
- A dose-response analysis found that ingestion of 2000 mg of l-carnitine per day may provide the maximum effect on body weight reduction 2.
- However, the effectiveness of carnitine supplementation may vary depending on individual factors, such as the presence of carnitine deficiency or other health conditions 4, 6.
Limitations and Potential Benefits
- While some studies suggest that carnitine supplementation may be effective for weight loss, the evidence is not yet conclusive, and more research is needed to fully understand its effects 2, 3.
- Carnitine supplementation may also have other potential benefits, such as improving heart health and reducing the risk of non-alcoholic fatty liver disease 4, 5, 6.