How much L-carnitine should I take for weight loss?

Quick Answer

The recommended L-carnitine dosage for weight loss is 500-2000 mg per day. Most studies have used doses of 1000-2000 mg of L-carnitine per day, split into two or three doses. L-carnitine supplements are considered safe at these dosages. Higher doses up to 4000 mg per day have been used short-term with no serious side effects reported. It’s best to start at a lower dosage like 500 mg once or twice per day and increase gradually over time to assess tolerance. Take L-carnitine with food to help increase absorption and reduce potential side effects like stomach upset.

What is L-Carnitine?

L-carnitine is a naturally occurring amino acid derivative that plays a key role in energy production. It helps transport fatty acids into the mitochondria of cells, where they can be oxidized to produce energy (1).

L-carnitine supplements have become popular for weight loss due to research showing it can:

  • Increase fat burning and energy expenditure
  • Reduce fat mass and body weight
  • Improve exercise performance and recovery

Some of the proposed mechanisms behind these benefits include:

  • Increasing fatty acid oxidation and utilization of fat for fuel
  • Reducing fat accumulation and transport into fat cells
  • Increasing mitochondrial activity and efficiency
  • Protecting against oxidative stress and inflammation

Evidence for Weight Loss Benefits

Several research studies support the use of L-carnitine supplements for weight loss:

  • A meta-analysis of 9 controlled trials found that L-carnitine led to a significant reduction in body weight of 1.33 kg and fat mass of 1.15 kg over a study period of 2-24 weeks (2).
  • One 12-week study in 80 overweight subjects found that 2 g/day of L-carnitine led to significantly more weight and fat loss compared to placebo. Body mass index (BMI) also declined more with L-carnitine (3).
  • Another study compared L-carnitine (2 g/day) and orlistat (prescription weight loss medication) over 24 weeks. L-carnitine led to slightly more weight loss and fat mass reduction compared to orlistat (4).
  • A study in 36 women found that those who took L-carnitine (1.5 g/day) for 8 weeks lost significantly more weight and body fat compared to a placebo group (5).

While promising, not all studies have observed weight loss benefits with L-carnitine supplementation. The positive effects seem most consistent at higher doses of 2-4 grams per day (2, 3).

Dosage for Weight Loss

Most studies showing weight loss effects have used an L-carnitine dosage range between 1,000-4,000 mg per day.

Here are some dosage guidelines based on the research:

  • The minimum effective dose for weight loss seems to be 1,000 mg per day.
  • For more pronounced effects, a dosage of 2,000-3,000 mg per day is recommended.
  • Doses up to 4,000 mg per day have been used safely in studies, but this high amount may increase the risk of side effects.
  • To start out, 500 mg once or twice per day can be used and slowly increased over time.
  • Taking L-carnitine with meals may help minimize potential side effects.

Based on a review of the research, a good general L-carnitine dosage recommendation for weight loss is:

  • 500-1000 mg with breakfast
  • 500-1000 mg with lunch or your main meal

This would provide an effective daily dose of 1000-2000 mg split into two portions. Higher daily doses up to 3000-4000 mg can be considered as well but may not be necessary for all individuals. Taking L-carnitine before/with meals containing carbs and fat will optimize its effects.

Maximum Safe Dosage

Human studies have used single L-carnitine doses up to 4000-6000 mg without serious adverse effects (6).

Doses above 3000 mg per day have been well tolerated but may increase the risk of digestive upset or nausea in some people. There is limited research on the safety of prolonged daily intake above 4000 mg per day.

For these reasons, a maximum dosage of 4000 mg per day is suggested unless under medical supervision. Doses above this amount could be cycled short-term under guidance from a doctor or dietitian.

In people with diabetes, kidney disease or taking blood thinners, a maximum of 2000 mg per day is recommended unless approved by your physician.

L-Carnitine Dosage Timing

Research on L-carnitine dosage timing is limited. Most studies have simply instructed participants to take it in divided doses with main meals.

Here are some general guidelines on timing:

  • Take with high-carb and high-fat meals – L-carnitine’s main role is to transport fatty acids for oxidation, so taking it with substantial fat/carb intake optimizes its effects.
  • Pre-workout – Some people take L-carnitine before workouts to increase performance and recovery. A dosage of 500-1000 mg can be taken 30-60 minutes pre-exercise.
  • Evening dose – Taking 500-1000 mg in the evening may help with fat burning overnight.
  • Between meals – L-carnitine absorption appears best when accompanied by dietary fat/protein. Taking it between meals offers less benefit.

Based on current evidence, splitting your daily L-carnitine dosage into 2-3 equal portions and taking it with main high-carb, high-fat meals appears most effective for weight loss.

L-Carnitine Forms

There are several forms of L-carnitine supplements available:

  • L-Carnitine base – This is the standard form and most studied for weight loss.
  • Acetyl L-Carnitine – Also known as ALCAR. May have added brain and nerve benefits.
  • L-Carnitine L-Tartrate – May be better for exercise performance and recovery.
  • Glycine Propionyl L-Carnitine – Glycine and propionyl group may increase blood levels.

For pure fat loss and metabolism benefits, L-Carnitine base is suggested since it’s the most researched.

Acetyl L-carnitine (ALCAR) can also be used as it may help fat burning while also improving brain function.

Glycine propionyl L-carnitine (GPLC) is another option that may achieve higher absorption compared to standard L-carnitine (7).

Overall the base form has been used most in weight loss studies, but ALCAR and GPLC are likely just as effective. Using different forms may provide greater benefit.

L-Carnitine Side Effects

L-carnitine is considered safe at standard doses of 500-2000 mg per day. Potential side effects are generally mild and may include:

  • Nausea, vomiting, stomach upset
  • Heartburn, diarrhea
  • Increased appetite
  • Unpleasant body odor
  • Rashes
  • Increased anxiety

Taking L-carnitine with food may help minimize digestive issues. Decreasing dosage and increasing slowly can also improve tolerance.

At higher repeated doses above 3000 mg per day, L-carnitine may potentially cause seizures in those with epilepsy or affect thyroid hormone levels. Long-term safety of high doses is unknown (8).

L-carnitine is likely unsafe during pregnancy and breastfeeding so should be avoided.

People with diabetes, liver, kidney, or heart conditions should use L-carnitine with caution or only after medical approval. Start with a lower dosage and monitor closely.

Inform your doctor if taking L-carnitine for weight loss, especially if you have any medical conditions or take medications.

How Long Does it Take to See Results?

At standard weight loss doses of 1000-2000 mg per day, L-carnitine may start working within several weeks but can take 2-3 months to see noticeable fat loss results.

Research studies have generally found significant reductions in weight and body fat over study periods of 2-6 months while using L-carnitine daily (2).

Results will vary based on your diet, activity levels, medical conditions, and dosage used. Patience and consistency are key.

L-carnitine is not a quick fix. It’s best used as a supportive supplement along with lifestyle changes to lose weight sustainably over the long-term.

Consider using L-carnitine for at least 3-6 months to see if you achieve your desired fat loss results. Adjust the dosage as needed based on your individual response.

Should You Cycle L-Carnitine?

There is limited research on whether L-carnitine needs to be cycled. Studies showing weight loss have involved daily use for up to 6 months.

Some people report benefiting from short L-carnitine cycles like 1 month on, 1 month off, or 2 weeks on/off.

This may help maximize fat burning effects in the body and offset potential side effects that can build up over time.

Listen to your body – if side effects become persistent or severe, take a break from supplementation.

Based on current evidence, L-carnitine can be taken daily for long periods. Cycling is likely unnecessary for most people at moderate dosages under 2000 mg per day.

Higher doses may be more suitable for short 4-8 week cycles with a break in between. As with any supplement, discuss cycling with your doctor.

Should You Stack L-Carnitine?

Some effective supplements to stack with L-carnitine for enhancing weight loss include:

  • Green tea extract – Boosts fat burning and provides antioxidants.
  • Conjugated linoleic acid (CLA) – Decreases body fat percentage while preserving muscle.
  • Forskolin – Activates fat burning enzymes and may increase L-carnitine effects.
  • Caffeine – Increases fat breakdown and utilization for fuel.
  • Fish Oil – Provides omega-3 fatty acids that optimize fat burning.

Taking a fat burning stack with L-carnitine, CLA, green tea extract, caffeine, and fish oil can accelerate weight loss results.

Always start supplements individually first before combining to check for tolerance and interactions. Discuss stacking with your doctor, especially if taking any medications or if you have health conditions.

L-Carnitine Alternatives

Some alternatives to L-carnitine for weight loss include:

  • CLA (conjugated linoleic acid) – Like L-carnitine, shown to reduce body fat percentage while preserving muscle mass.
  • Green coffee extract – Contains chlorogenic acid that may decrease fat absorption and body fat levels.
  • Green tea extract – Boosts fat burning through its active ingredient EGCG.
  • Glucomannan – A soluble fiber that can decrease appetite and promote weight loss.
  • Meratrim – A proprietary blend of two herbal extracts that may change how the body metabolizes fat.

These supplements can be taken alone or potentially stacked with lower doses of L-carnitine. As always, consult your healthcare provider before starting any new supplements.


Based on the research, L-carnitine is an effective supplement for weight loss. Most studies showing significant fat loss have used dosages between 1000-2000 mg per day.

To start out, 500 mg once or twice daily with food can be used. This can be gradually increased over time up to 2000-4000 mg per day in divided doses with meals if you have no side effects.

At appropriate dosages, L-carnitine is generally safe long-term and very effective as part of a comprehensive weight loss regimen including diet, exercise and lifestyle changes. Use L-carnitine consistently for at least 2-3 months to see optimal results.

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