How Acetyl-L-Carnitine Burns Fat and Powers the Brain

Acetyl-L-carnitine (ALCAR) is a powerful addition to your supplement toolbox. This valuable little molecule has been a staple in the bodybuilding and brain-hacking communities for years now, thanks to its ability to help you lose weight and power up your brain. Read on to learn more about the benefits of acetyl-L-carnitine, plus side effects, safety and dosage.

What is acetyl-L-carnitine?

ALCAR is an amino acid naturally produced in your body that is necessary to generate energy.^[1] It’s also found in animal protein — namely, red meats. Many people supplement with ALCAR, because of its potential benefits.

What are the benefits of acetyl-L-carnitine?

You can use ALCAR to enhance your mitochondrial function, cognition, workouts and more. ALCAR helps your mitochondria (the powerhouses of your cells) burn fat and create more energy — especially for your muscles and brain.

Acetyl-L-carnitine has two main benefits:

• Supports brain health: ALCAR acts as a nootropic, or smart drug, meaning it helps your brain perform better. The acetyl group on it lets it pass your blood-brain barrier and reach your brain and nerves, where it can help support healthy mood, learning and memory.^[2][3]
• Burns fat and builds muscle: ALCAR may give you an edge in the gym, too. It shuttles fuel (in the form of fatty acids) to your muscle mitochondria, which ramps up your energy production and may increase endurance. ALCAR also pushes your metabolism toward fat burning while you work out.

Acetyl-L-carnitine and weight loss: How it helps burn fat

When you take ALCAR, it turns into carnitine in your body. If your insulin levels are low — for example, from eating a keto diet, intermittent fasting, working out intensely or being in a calorie deficit — carnitine becomes very important for burning fat.

When your body burns fat for fuel, it takes stored body fat (or fat you eat) breaks it down into fatty acids and sends the fatty acids to your mitochondria.^[4] Your mitochondria turn those fatty acids into ATP (energy) that powers your cells.

But fatty acids can’t get into your mitochondria alone. They use something called a carnitine shuttle.^[5] Basically, carnitine latches onto fatty acids and carries them into your mitochondria. It gives your mitochondria the raw materials to produce lots of energy and function at their best.

In other words, you need carnitine to metabolize fat. If you’re low on carnitine, fat can’t get into your mitochondria, and you struggle to use it for fuel.^[6] But with abundant carnitine, your fat metabolism works like a well-oiled machine. That’s where ALCAR supplements come in, and why they’re so popular with bodybuilders.

The bottom line: To burn fat, your body breaks it down into fatty acids, and ALCAR helps get those fatty acids into your mitochondria where it can be used as fuel.

Related: 13 Anti-Aging Supplements to Turn You Into Benjamin Button

Acetyl-L-carnitine for mood, memory and cognitive decline

ALCAR in supplement form can pass your blood-brain barrier, giving it access to the dense collection of mitochondria in your brain, as well as to the mitochondria in the rest of your body. That explains why ALCAR is becoming so popular as a nootropic supplement (something that makes your brain work better).

Here’s what the research has to say about using ALCAR to make your brain work better:

• More mental and physical energy: Older men and women who took ALCAR daily saw a significant boost to their physical and mental energy levels, as well as better overall cognitive ability.^[7]
• Supports cognitive function: People with low carnitine levels see a major decrease in brain function. Taking ALCAR supports that brain function. A lot. In a 2010 study, eight out of 14 participants with some cognitive decline, returned to their full cognitive abilities after taking ALCAR daily.^[8]
• May help to with antioxidant needs and brain health: LCAR increases glutathione, your body’s master antioxidant.^[9] Additionally, ALCAR may help to protect brain cells during and after drinking.^[10]
• Supports circulation: In healthy adults, ALCAR promoted circulation and nutrient-rich blood flow after a high-fat meal.^[11] Good blood flow is an essential part of muscle and brain function.
• Promotes better focus: Acetyl-L-carnitine promotes better attention, both in kids and adults who struggle with mental fatigue.^[12][13]

The bottom line: In studies, ALCAR has been shown to support mental and physical energy, brain power, circulation and mental focus.

Who should use acetyl-L-carnitine as a nootropic?

It’s worth mentioning that, although a few of these studies are in healthy young adults, a lot of ALCAR research is in older people. It’s clear that ALCAR is great for aging, but what if you’re young and thriving, and want an extra edge?

As is the case with many nootropics, ALCAR is popular in the brain-hacking world thanks to lots of individual reports about how much it helps cognition. This is one of those supplements that’s worth trying on your own to see if you notice any benefit.

Acetyl-L-carnitine for exercise and recovery

ALCAR has been a staple of the bodybuilding community for years. It’s got some decent research to back it up:

• Supports strength training: In a study of 24 resistance-trained young men who took carnitine 90 minutes before intense exercise, participants enjoyed a significant increase in power output, as well as lower lactate levels (lactate contributes to the burning feeling in your muscles).^[14]
• Burns more fat: Young men who took carnitine burned more fat during moderate exercise, and their muscles produced more energy during intense exercise.^[15]
• Boosts testosterone use: Men who took ALCAR after lifting had more dense hormone receptors in their muscles, which may have improved their testosterone uptake.^[16] In other words, ALCAR doesn’t increase your testosterone; it makes you better at using the testosterone you have.
• Speeds recovery: ALCAR can speed up recovery and muscle health after exercise, in both men and women.^[17]
• Better insulin sensitivity: ALCAR supports insulin sensitivity in people who don’t process glucose well.^[18]
• Supports muscle: In older people, ALCAR helps with muscle fatigue and promotes fat loss.^[19]
• Helps with muscle fatigue: One study found that acetyl-L-carnitine helped with muscle fatigue in young people, too.^[20]

The bottom line: ALCAR can help you work harder in the gym and recover faster. And if you’re older, ALCAR is especially useful for maintaining your energy levels and shedding body fat.

Related: Creatine Benefits: How This Supplement Works for More Than Muscle

Dosage: How much acetyl-L-carnitine should you take?

Acetyl-L-carnitine is a valuable addition to your daily supplement routine, especially if you’re an athlete. Here’s what you need to know.

Most of the studies you just read about used between 1-3 grams of ALCAR, taken every day. One gram a day seems to be a good place to start.^[21] From there, you can increase or decrease the dose as you see fit. As with most supplements, timing matters. Here are sample plans for taking ALCAR:

• Acetyl-L-carnitine for nootropic benefits: 1-2 grams per day; half first thing in the morning and half in the afternoon
• Acetyl-L-carnitine for fitness and fat-burning: 1-3 grams per day; half 90 minutes before exercise (to promote muscle endurance) and half after exercise (to speed up recovery).

Be sure to consider any dosage instructions on the supplement packaging.

Acetyl-L-carnitine side effects and precautions

While ALCAR is generally considered safe for most people, you could experience some side effects, including:^[22]

• Upset stomach
• Nausea
• Vomiting
• Headache
• Dry mouth
• Restlessness

Of course, consult your physician before starting any new supplement, especially if you’re pregnant, breastfeeding or have a serious medical condition.

If you try ALCAR, start slow and pay attention to the way you feel. Small changes help you discover big benefits — this is what being Bulletproof is all about. To discover even more ways to boost your performance, sign up for the Bulletproof newsletter below.

This is an update of an article originally published July 2018.