L-carnitine: Does it aid weight loss?

L-carnitine has long been thought to lead to weight loss due to its effects on lipid metabolism. The term carnitine is derived from the Latin word carnus, which means flesh. The term is appropriate as animal meat remains the most significant source of L-carnitine. 

Made from the amino acids lysine and methionine, L-carnitine plays a critical role in the breakdown of fats to form adenosine triphosphate (ATP), the energy currency of the cells. 

Once inside the cells, L-carnitine transports long-chain fatty acids into the mitochondria, an organelle considered the cell’s powerhouse. The mitochondria is a double sac organelle where glucose and lipids are broken down and metabolized to form ATPs. 

L-carnitine is essential in detoxifying mitochondria by ferrying out toxic compounds and preventing their accumulation. Hence, L-carnitine protects the mitochondria while ensuring that the organelle exports sufficient ATPs to power up chemical reactions in the cells.

Is L-carnitine proven for weight loss?

Since L-carnitine has a vital role in the metabolism of lipids, this critical compound may help people lose weight. 

A systematic review [1] and meta-analyses of 37 randomized controlled clinical trials reported that supplementation with L-carnitine significantly decreased body weight, body mass index and fat mass.

A total of 2,292 participants were recruited in the 37 randomized controlled trials. Pooling these study participants’ findings strengthened the results of the systematic review. 

On average, individuals who took L-carnitine supplementation lost 1.21 kg, with some losing as high as 1.73 kg and others losing only 0.68 kg. The average body mass index reduction was -0.24 kg/m2, and fat mass was reduced by -2.08 kg. 

The clinical trial participants ingested 2000 mg of L-carnitine daily. They experienced significant weight loss but no significant changes in their body fat percentage or BMI.

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The study, published in the Clinical Nutrition Espen and led by investigators from the University Medical Sciences in Iran, reiterated that the most significant weight change was seen in those who were obese or overweight at the beginning of the study. 

The findings of this study have important implications for weight loss and the use of L-carnitine, especially in overweight and obese individuals. Since meta-analysis reduces the risk of bias, the results can be used to inform healthcare practice. 

If you plan to lose weight, you can follow a healthy diet and lifestyle and exercise. You can then consult your doctor about taking an L-carnitine supplement to support your weight loss journey. 

Meanwhile, another systematic review and meta-analysis [2] also prove that L-carnitine supplementation can lead to weight loss. The study, published in the Obesity Reviews journal, analyzed nine randomized controlled trials that recruited 911 participants. 

The findings of this review showed that those taking L-carnitine registered an average weight loss of -1.43 kg and a reduction in BMI of -0.47 kg/m2 compared with the control group. Importantly, subgroup analysis demonstrated that the effects were the greatest in those who were obese or overweight at baseline. 

Based on these two high-quality reviews, ingestion of L-carnitine can aid in weight loss. A dosage of 2000 mg daily over long periods is needed to see significant weight loss reductions. 

What are the food sources rich in L-carnitine?

If you are planning to get L-carnitine from the food that you eat, be sure to include the following in your diet: 

  • Ground beef
  • Beef steak 
  • Pork meat 
  • Whole milk
  • Cooked cod fish
  • Chicken breast 
  • Cheddar cheese 
  • Whole wheat bread 
  • Cooked asparagus 
  • A serving size of these foods is enough to help you get the recommended amount of L-carnitine for your body. 

Remember, eating healthy food and exercising are two essential strategies for losing weight. Supplementation with L-carnitine can significantly reduce weight compared to those who do not take L-carnitine supplements.

However, the average weight loss is less than 2 kilograms. Hence, the best way to achieve your weight goal is to support L-carnitine supplementation with diet and exercise. 

How to use l-carnitine for weight loss

Are there different types of L-carnitine?

When considering L-carnitine supplements, it’s important to know that there isn’t just one type available. Each type has its own characteristics and potential benefits. Here, we’ll break down the main types of L-carnitine supplements:

1. L-carnitine

This is the most basic form of L-carnitine. It’s widely used and readily available. L-carnitine is primarily used to support overall energy production and fat metabolism. Dosage typically ranges from 500 mg to 2,000 mg per day.

2. L-carnitine L-Tartrate (LCLT)

LCLT is known for its potential benefits in exercise performance and recovery. It may help reduce exercise-induced muscle damage and soreness. 

Athletes and those engaged in intense physical activity often opt for LCLT. The suggested dosage is around 1,000 mg to 2,000 mg per day.

3. Acetyl-L-carnitine (ALCAR)

ALCAR is commonly used to support brain function and cognitive health. It may help improve memory, focus, and mood. 

Some studies suggest it may also have a role in weight management. The dosage usually ranges from 600 to 2500 mg per day, divided into two or three doses.

4. Propionyl-L-carnitine (PLC)

PLC is often used to promote cardiovascular health. It may help improve blood flow and reduce symptoms in individuals with certain cardiovascular conditions. 

Some studies suggest it can enhance exercise tolerance. The recommended dosage typically ranges between 500 and 1,000 mg per day, taken in divided doses with meals to maximize absorption.

5. Glycine Propionyl-L-carnitine (GPLC)

GPLC is a combination of L-carnitine and glycine. It’s used for both cardiovascular health and exercise performance. 

Some research suggests it may have superior bioavailability. Dosage typically ranges from 500 mg to 2,000 mg per day.

6. Carnitine Fumarate

This form combines L-carnitine with fumaric acid. It supports overall health and energy production. Carnitine fumarate is often included in some comprehensive multivitamin supplements. The dosage varies depending on the product.

The type of L-carnitine you select should align with your intended benefits, whether that’s supporting weight loss, exercise performance, cognitive function, or cardiovascular health.

Additionally, always follow recommended dosages and be consistent with your supplementation regimen for the best results.

Lifestyle considerations

Is L-carnitine safe for long term use?

While L-carnitine is lauded as an essential compound in helping skeletal muscles and heart muscles to utilize energy from the mitochondria effectively, it might influence the development of heart diseases. 

L-carnitine can be sourced naturally from food such as red meat. Evidence from literature has consistently pointed out that red meat remains the most abundant source of L-carnitine. As a rule, the redder the meat, the more L-carnitine content. 

A serving size of cooked beef, about 113 grams or 4 ounces, contains 56 to 162 mg of L-carnitine. This amount of L-carnitine in a serving size of meat constitutes 11.2% to 32.4% of the recommended daily allowance (RDA) for this nutrient. 

However, an older study published ten years ago [3] suggests that overconsumption of red meat could lead to cardiovascular diseases. 

Authors of the study, led by Robert Koeth from the Department of Cellular and Molecular Medicine at the Cleveland Clinic in Ohio, explained that the link between ingestion of red meat and cardiovascular disease might be due to the actions of intestinal microorganisms. 

The intestinal microbiota, composed of different microorganisms, metabolizes choline/phosphatidylcholine to produce a compound called trimethylamine (TMA). The TMA is further metabolized to form trimethylamine-N-oxide (TMAO). 

The gut microbiota has been shown to metabolize dietary L-carnitine to TMAO, which hastens the thickening of the arterial blood vessels with fatty deposits. This thickening results in atherosclerosis, the buildup of fatty deposits in the walls of the arteries that leads to coronary heart disease. 

Robert Koeth also cited animal studies that demonstrated that chronic L-carnitine supplementation resulted in increased synthesis of TMAO and increased risk of atherosclerosis, stroke and heart disease. 

Based on this study, a moderate intake of red meat is necessary to prevent heart disease or atherosclerosis. Ingesting just one serving size per day may be sufficient to increase L-carnitine in the body. Eating other foods rich in L-carnitine could help you reach the required amount of this supplement daily. 

However, if it is difficult to reach the required daily allowance of L-carnitine, which ranges from 500 to 2000 mg/daily, you can take L-carnitine supplementation. Always talk to your doctor before taking L-carnitine supplements.

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Are there any negative effects of L-carnitine?

While L-carnitine is generally safe for many people, it’s important to be aware of some potential side effects and considerations:

  • Digestive issues: Some individuals may experience nausea, stomach upset, or diarrhea. This is usually related to higher doses.
  • Fishy odor: High amounts of L-carnitine can lead to a noticeable fishy body odor [4].
  • Muscle weakness: In rare cases, especially in people with prior conditions like seizures or thyroid problems, L-carnitine might cause muscle weakness.
  • Interaction with medications: L-carnitine can interact with certain medications, such as blood thinners and thyroid hormones. Always check with a healthcare provider before starting.

If you’re pregnant, nursing, or have a medical condition like liver or kidney disease, it’s crucial to consult your doctor before taking L-carnitine. Starting any new supplement should be a careful decision guided by professional advice.

Closing thoughts

Maintaining a healthy weight prevents type 2 diabetes mellitus and cardiovascular diseases. Eating the recommended amount of calories daily is essential in keeping off unwanted weight. 

Research studies have suggested that taking L-carnitine supplements may help you lose weight. However, the recorded weight loss from these studies was, on average, less than 2 kilograms. 

It should be noted that the supplementation in the studies was only for a few weeks or months. It is still being determined if the weight loss effects could be sustained over time or whether more prolonged supplementation would lead to more weight loss. 

To date, exercise and a healthy diet are two of the best strategies to lose weight. Taking L-carnitine supplements with these two strategies could lead to increased weight loss. 

Finally, consult with your doctor if you are planning to take L-carnitine supplements to lose weight.


How much carnitine should I take a day to lose fat?

The recommended daily dosage of L-carnitine for fat loss typically ranges from 500 mg to 2,000 mg. Still, it’s crucial to consult with a healthcare professional to determine the appropriate amount based on your individual needs and goals.

How long does it take to lose weight with L-carnitine?

The time it takes to see weight loss results with L-carnitine can vary widely depending on factors like diet, exercise routine, and overall metabolism. Some individuals may notice changes within a few weeks, while others may take several months to experience significant weight loss.

Why is L-carnitine good for weight loss?

L-carnitine is considered beneficial for weight loss because it transports fatty acids into the mitochondria, where they are burned for energy. This can enhance the body’s ability to use stored fat as a fuel source during physical activity, thereby supporting weight loss when combined with a healthy diet and regular exercise.

How long does it take to see results from L-carnitine?

Results can vary, but some people may notice improvements in energy and endurance within a few weeks. Consistent use over several months is typical for evaluating its effectiveness for weight loss.

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[1] https://pubmed.ncbi.nlm.nih.gov/32359762/ 
[2] https://onlinelibrary.wiley.com/doi/10.1111/obr.12436 
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3650111/ 
[4] https://www.webmd.com/vitamins/ai/ingredientmono-1026/l-carnitine

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