Some people claim that conjugated linoleic acid (CLA), a type of fatty acid, can be taken as a supplement to aid weight loss. However, human studies have not proved its efficacy or safety.

Animal studies investigating CLA for weight loss indicate CLA supplementation has value, but human studies have not yet replicated these results.

Additionally, it is important to note that some animal research suggests CLA may cause inflammation and increased fat in the liver.

Read on to learn more about CLA for weight loss, including research findings, side effects, dosage, and food sources.

A sunflower -2.Share on Pinterest
Elizabeta Istrate/500px/Getty Images

CLAs are naturally occurring isomeric polyunsaturated fatty acids. Isomers are compounds with the same chemical formula but different arrangements of the atoms they are made of. The CLA isomer that researchers associate with weight loss is called 10,12 CLA.

According to research, the bacteria in the gut of certain animals produce CLA. This includes:

  • sheep
  • cattle
  • goats
  • deer

Additionally, CLA is available in an industrialized form. A 2019 study states that manufacturers can make it from oils rich in linoleic acid, such as:

  • safflower
  • corn
  • sunflower
  • soybean

While CLA may aid in weight loss, researchers do not recommend it because of conflicting evidence studies provide.

According to a 2017 study on mice, CLA supplementation can reduce weight, but it does not do this in an ideal way. The weight loss is largely due to a reduction of subcutaneous fat instead of visceral fat. Subcutaneous fat lies underneath the skin, while visceral fat lies around internal organs in the belly.

Visceral fat causes more risks and can have negative health consequences. It is also linked to a higher death rate, as outlined in a 2022 research review.

The authors of the study concluded that CLA-related weight loss is less metabolically healthy than other weight loss methods, such as calorie restriction.

Research notes that unlike animal studies on CLA, which suggest a dramatic weight loss effect, human studies are not promising or considerable.

Studies involving humans have not proved the safety and efficacy of CLA.

A 2019 meta-analysis on the effects of CLA on body composition suggests that CLA side effects include:

  • nausea
  • stomachache
  • diarrhea
  • bloating
  • headaches
  • skin rashes

However, some people may tolerate it well.

Additionally, weight loss from CLA does not link to improved glucose metabolism like weight loss from calorie restriction. It is instead associated with insulin resistance, a condition where cells do not respond adequately to insulin and cannot easily take up glucose from the blood.

A 2022 meta-analysis suggests that CLA increased triglycerides, total cholesterol, and LDL but also increased HDL.

A 2019 literature review looked over research to date on CLA. It included trials using doses ranging from 1.5 to 6.8 grams (g) per day. It found that doses higher than 3.4 g a day were more likely to reduce body weight than lower doses.

However, because research on safety and effectiveness is lacking, a safer option would involve eating foods that are naturally enriched with CLA.

Food sources include notes that CLA sources include milk and milk products such as cheese and yogurt. Certain types of meat also contain CLA. These include lamb and beef.

CLA is a family of naturally occurring isomers of fatty acids that are present in some animal foods. While some people claim that CLA supplements aid in weight loss, research on CLA for weight loss in humans is not promising.

The supplement produces a loss of subcutaneous rather than visceral fat, which poses a higher likelihood of adverse health outcomes.

Consequently, scientists do not consider it a healthy means of weight loss and urge further studies to explore its safety and effectiveness.

A person thinking of taking a CLA supplement should talk with a healthcare professional first.