Conjugated linoleic acid (CLA) is a fatty acid studied for its role in weight management. Derived from linoleic acid, an omega-6 fatty acid, CLA is often associated with changes in body composition and fat reduction. This article explores what CLA is, its potential influence on weight, the scientific evidence, and supplementation considerations.
What is Conjugated Linoleic Acid?
Conjugated linoleic acid (CLA) is a naturally occurring polyunsaturated omega-6 fatty acid. It is primarily found in meat and dairy products from ruminant animals like cows, sheep, and goats. The amount of CLA in these foods varies with farming techniques, with grass-fed animal products generally containing higher concentrations.
CLA exists in various forms called isomers. The two most studied for health effects are cis-9, trans-11 CLA and trans-10, cis-12 CLA. While cis-9, trans-11 CLA is the most abundant in natural food sources, synthetic CLA supplements often contain roughly equal proportions of both.
How Conjugated Linoleic Acid May Influence Weight
CLA’s potential influence on body weight and composition is largely based on laboratory and animal studies. One theory suggests CLA may reduce body fat by affecting fat metabolism. It might decrease fat accumulation in adipose tissue by inhibiting lipogenesis (fat creation) and increasing lipolysis (breakdown of stored fat).
CLA is also thought to influence energy expenditure, potentially by increasing the body’s metabolic rate or promoting lipid oxidation, which is the burning of fat for energy. Some research suggests a role in preserving or increasing lean muscle mass, contributing to a higher metabolic rate. These actions aim to shift the body’s balance towards less fat storage and greater fat utilization.
Scientific Findings on Conjugated Linoleic Acid and Weight Management
Human clinical trials on CLA’s effectiveness for weight loss and body composition have yielded inconsistent results. Some studies show modest benefits in reducing body fat, while others report minimal or no significant effect. A meta-analysis found that CLA, at 3.2 grams per day, produced a modest reduction in body fat in humans. This effect was observed for up to six months, then slowly plateaued over two years.
The effects in human studies are generally small, often resulting in an average fat loss of about 0.2 pounds (0.1 kg) per week for six months, or about 3 pounds (1.3 kg) more weight loss than a placebo. Animal studies, in contrast, frequently show more pronounced effects, with rodents sometimes experiencing a 50% decrease in body fat. However, these animal studies often use significantly higher doses of CLA per kilogram of body weight compared to human trials.
Considerations for Supplementation
Individuals considering CLA supplementation should be aware of typical dosages, potential side effects, and precautions. Studies generally use CLA doses from 1.5 to 6.8 grams per day, with many suggesting a minimum of 3 grams daily for weight loss effects. Doses up to 6 grams per day are typically considered safe, and the U.S. Food and Drug Administration (FDA) has given CLA “generally regarded as safe” (GRAS) status for food addition.
Some individuals may experience mild side effects, including digestive upset, diarrhea, nausea, fatigue, and headaches. More serious concerns, though rare, include potential impacts on liver function, increased fat accumulation in the liver, or adverse effects on insulin sensitivity, particularly with higher doses. Always consult a healthcare professional before starting any new supplement, especially if you have pre-existing health conditions like diabetes or heart disease, or are taking medications, as CLA might slow blood clotting. Supplements are not a substitute for a healthy diet and regular exercise, which remain the most effective strategies for weight management.