Does conjugated linoleic acid work for weight loss?

You've probably considered natural supplements if you're on a weight loss or bodybuilding journey. Many people swear by dietary supplements for boosting their energy or providing other benefits as they adapt to new diets or more intense exercise routines. While no dietary supplement can replace a healthy lifestyle, certain supplements may play a role in steady progress toward your goals. 

Some over-the-counter dietary supplements promoted for weight loss and muscle-building contain an ingredient called conjugated linoleic acid (CLA). It’s a popular supplement among bodybuilding enthusiasts for its reported ability to increase muscle mass, burn fat, and enhance athletic performance. Even though many people like it, there isn't much proof backing up these claims, and there have been reports of not-so-great side effects.

Keep reading to learn more about CLA, including its potential health benefits, effectiveness for losing weight and building muscle, possible side effects, and who is better off avoiding it. 

Conjugated linoleic acid (CLA) is a type of fat found in foods such as milk, meat from cows and goats, and some vegetable oils. CLA is naturally made in the bodies of animals like cattle, deer, sheep, and goats. The amount of CLA in animal products can vary based on the animal’s dietary intake and environment. For instance, cows fed more grass may produce milk with a higher CLA content.

CLA supplements are commonly marketed as a strategy for fat-burning and muscle-building, among other potential benefits. But the scientific evidence is questionable, and, like most supplements, it does not come without potential adverse effects. 

The major dietary sources of naturally occurring CLA are beef and dairy products like milk and yogurt. However, these sources contain a different ratio of the forms of linoleic acid compared to most dietary supplements containing CLA. Further, there is evidence that these different configurations of linoleic acid have different effects and may act through different mechanisms. So, CLA supplements provide a different CLA than you would get from eating foods like beef and dairy products.

Plant oils such as safflower oil also contain CLA, but the concentration is much lower than animal-based sources. Plant oils are also a source of linoleic acid, which may be converted to CLA in humans by the gut microflora (the “good” bacteria residing in our intestines). However, it is not believed to be converted into a significant amount.

Here’s what the science has to say about  CLA supplements’ most common health claims:

Weight loss

Animal studies have analyzed the effect of CLA on body composition, with many showing that CLA reduces body fat. Based on the mixed but promising results of animal studies, there was hope that CLA may similarly affect human body composition. However, the trials studying CLA in humans have had mixed results—meaning the results of some studies suggest effectiveness while others do not. 

Many experts have proposed different mechanisms by which CLA could lead to weight loss and changes in body composition, but it's not fully understood yet. CLA seems to help with body composition and modest weight loss by stopping your body from storing too much fat and helping maintain your muscles. 

CLA supplements might also make you feel less hungry and more satisfied, but this doesn't necessarily mean you'll eat less or lose weight. In a 2003 study, CLA supplementation was shown to have an appetite-suppressing effect but was not found to cause lower energy intake or improved body weight maintenance. This was the result regardless of the dosage taken (1.8 or 3.6 grams of CLA per day). 

Daily CLA supplementation (3-6.8 grams per day) may cause a modest decrease in body fat, increase lean body mass, and reduce the circumference of the waist and hips, based on available research. In an analysis pooling the data of 18 other studies, CLA supplementation was linked to a fat loss reduction of about 0.09 kilograms (~2 pounds) per week compared to placebo. Many of these studies were short-term. Further studies are needed to understand the long-term effects of oral CLA supplementation on weight loss and body composition.

A 2010 study compared the effects of CLA supplements to placebo in kids considered overweight compared to other kids their age (6-10 years old). After seven months, the children who took 3 grams of CLA daily had reduced body fat and abdominal fat compared to those who took the placebo. However, a long-term investigation of the safety and efficacy of CLA supplementation is needed. 

Overall, CLA supplementation seems to modestly decrease body fat, but not reliably. Further research is needed to clarify the benefits and understand how CLA affects metabolism and body weight.

Athletic performance

CLA supplements are often marketed for boosting athletic endurance and performance, but there’s little proof they work as promised.

Taking 900 mg of CLA powder daily for two weeks might help student-athletes exercise longer before they reach the point of exhaustion, according to a 2017 study. However, this study did not find CLA to help reduce how quickly the athletes perceived feeling exhausted.

Other small clinical trials found no improvement in athletic performance in people with moderate to no athletic training. 

So, there isn’t enough evidence to say whether taking CLA supplements can improve your performance in sports or workouts.

Cardiovascular health

CLA might be linked to cardiovascular benefits, but researchers haven’t consistently found this to be true. 

Research from 2009 suggests that CLA supplementation can slightly lower blood pressure when used along with ramipril, a commonly prescribed blood pressure medication. However, a 2015 study found that oral CLA supplementation did not affect blood pressure.

Having high cholesterol can increase the risk of serious heart problems. Despite some claims, CLA products do not seem to affect cholesterol. 

Taking CLA supplements for eight weeks didn't make any improvements in total cholesterol, LDL (“bad” cholesterol), HDL (“good” cholesterol), or triglyceride levels when compared to a placebo in a 2010 study. Another 8-week study in females with obesity examined the effects of CLA supplementation paired with regular aerobic exercise. The results showed no improvement in cholesterol or triglyceride levels compared to the exercise regimen alone.

Although some companies promote CLA products for heart health, there isn’t sufficient evidence to support these claims.

Additional health benefits of CLA

Researchers have studied CLA to see if it has additional health benefits. Some of their conclusions are:

• Bone health? Maybe. The findings of animal studies and lab research in cells suggest that CLA may increase bone mineral content and bone formation. Population-based research also suggests that higher dietary intake of CLA may be associated with increased bone density.

• Anti-diabetes effects? Probably not. Based on limited clinical research from 2009 and 2013, CLA supplements do not seem to help much with managing diabetes. CLA supplementation was not linked to improvements in fasting or post-meal blood sugar levels. 

• Common cold? Not likely. It’s been suggested that CLA supplements might help the common cold (rhinovirus). However, in a clinical study, taking CLA did not reduce the risk of catching a cold nor lessen the severity of cold symptoms, such as cough and sore throat. 

CLA doesn’t seem to cause side effects when consumed via dietary intake of foods containing CLA. CLA, taken as an oral supplement, is also generally well tolerated. Reported side effects of oral CLA supplementation include stomach upset, such as bloating, indigestion, diarrhea, or nausea. However, most CLA studies were short-term, so little is known about its long-term safety and side effects.

Based on the study that found slight blood-pressure-lowering effects with CLA, it is unlikely but possible that people taking blood pressure medications could experience hypotension (blood pressure that’s too low and may cause dizziness). If you’re being treated for high blood pressure, it’s a good idea to consult a healthcare provider before taking CLA. If your provider thinks CLA would be safe for you, they may suggest monitoring your blood pressure at home to watch for any changes in your blood pressure readings. 

In addition, CLA supplements might interact with anticoagulants (blood thinners) or antiplatelet medications, raising the risk of bruising or bleeding. People taking these medications should consult a healthcare provider before taking CLA. Examples are:

• Apixaban (Eliquis)

• Aspirin

• Cilostazol (Pletal)

• Clopidogrel (Plavix)

• Dabigatran (Pradaxa)

• Enoxaparin (Lovenox)

• Prasugrel (Effient)

• Rivaroxaban (Xarelto)

• Ticagrelor (Brilinta)

• Warfarin (Coumadin, Jantoven)

Most people consume 15-174 milligrams of CLA daily in their diet, mainly from milk, dairy products, and beef. Because CLA supplements are not approved for any medical purpose by the Food and Drug Administration (FDA), there isn’t an FDA-approved dosage. Instead, CLA supplement dosages are generally based on the amounts used in research studies.

The CLA dose range most extensively studied for weight loss is 3 to 6.8 grams daily for 2 to 12 weeks. Doses greater than 3.4 grams daily do not seem to offer additional benefits compared to lower doses in terms of reducing body fat, according to research from 2007. CLA has also been shown to slightly reduce hunger and improve feelings of fullness at either 1.8 or 3.6 grams daily. 

In a 2010 study of CLA supplementation in overweight children ages 6 to 10 years old, a dosage of 3 grams daily for 7 months was used. However, there are no definitive dosing recommendations for children. Consult your child’s healthcare provider before giving them CLA.

Be sure to follow the dosing instructions on the label of your CLA supplement.

If you’re considering CLA supplements for weight loss, a more evidence-backed alternative may be a better use of your time and money. A more worthwhile approach may be incorporating more CLA-rich foods into your diet rather than taking a supplement. While CLA supplementation may be relatively tolerable in the short term, the long-term effects aren’t known, and it could even be harmful in people taking certain medications.

Based on current evidence, the most effective weight loss medications include semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro). 

The best thing to do is to consult a healthcare professional to determine if CLA supplementation is safe for you based on your overall health and medical conditions. They can help you devise a weight loss plan tailored to your needs. 

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

September 19, 2023

Written by

Patricia Weiser, PharmD

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.