Visit any health food store, and you’ll find a variety of supplements that claim that they’ll help you lose weight. Carnitine, or acetyl-L-carnitine, is an ingredient in some of these products. Unlike some weight loss products with dubious ingredients, there is some science behind using carnitine as a supplement for weight loss.
What is Carnitine?
Carnitine is a compound synthesized from two amino acids, methionine and lysine. There are two forms of carnitine, D-carnitine, and L-carnitine, although L-carnitine is the only form that has any activity in the body.
L-carnitine plays an essential role in fat metabolism. It delivers long chain fatty acids to a cell’s mitochondria where they can be broken down for energy through a process called beta-oxidation. L-carnitine helps to boost the use of triglycerides as energy, which means there’s less lying around to be stored as hip, thigh and tummy fat.
Some experts have also proposed that carnitine boosts exercise endurance by stimulating the breakdown of triglycerides for energy thereby sparing glycogen stores. It certainly makes sense from a physiological standpoint. But does it hold up in real life?
Does Research Show L-Carnitine Helps with Weight Loss?
This is where the issue becomes less clear-cut. Research looking at whether L-carnitine increases weight loss has been inconsistent. Although taking L-carnitine as a supplement appears to be safe, there’s no solid evidence that using it will help you lose weight unless you’re already carnitine deficient. This also holds true for its endurance boosting benefits.
On the other hand, some people may be deficient in carnitine, especially those who eat a mostly plant-based diet. The best food sources of carnitine are meat and dairy foods, especially red meat, pork, chicken and lamb. Dairy sources such as milk and cheese only have a fraction of the carnitine found in red meat. A few plant-based foods have carnitine at levels similar to dairy foods. These include avocados and asparagus.
Since the body can also make carnitine, it’s not clear whether vegetarians and vegans really need it from food sources if they eat a healthy diet. On the other hand, a diet that’s deficient in vitamin C or iron increases the risk of carnitine deficiency since they’re involved in its synthesis. It’s not uncommon for vegetarians and vegans to be iron-deficient.
Carnitine levels also decline with age, so older people may have a deficiency that could make it more difficult for them to lose weight. In addition, some people have problems making adequate amounts of carnitine for genetic reasons, and people with kidney disease may also be deficient.
For young, healthy people who don’t eat an exclusively plant-based diet, there’s not a lot of evidence that taking L-carnitine supplements boosts weight loss or exercise endurance, although the book isn’t completely closed on this issue. At the very least, supplementing with L-carnitine doesn’t appear to be harmful although supplements can be expensive.
The Bottom Line?
L-carnitine supplements may be useful for weight control if you’re deficient for genetic reasons or if you’re a vegetarian or vegan who doesn’t get enough vitamin C or iron. For everyone else, there’s not a lot of evidence that supplementing with L-carnitine will help shed body fat or help you exercise longer or harder than you normally could. Unfortunately, swallowing a supplement to lose weight usually produces disappointing results. Clean eating and a combination of resistance training and fat-burning exercise are still the best way to shed body fat.
References:
Vanderbilt University. L-Carnitine: Powerful Endurance Enhancer or Unnecessary Ergogenic?
University of Maryland Medicine Center. “Carnitine”
