CLA is a term used to describe a mixture of fatty acids that contain 18 carbon atoms and two double bonds. They are a form of polyunsaturated fat, though may also exist as a trans fat. During normal conditions, CLA is found in small amounts in beef, whole milk and whole milk products such as cream or cheeses, but it can also be taken as a supplement, typically in a liquid soft gel in doses of around 2,000-6,000mg per day.
In animal studies it seems to be really effective at improving body composition and even health markers, and there seems to be some data to show that humans can benefit from it, too. However, it’s not as straight forward as the adverts may have you believe…
In one research paper that actually tested CLA in resistance training individuals, the average muscle increase for the CLA group was 1.4kg over seven weeks compared to 0.2kg in the placebo group. In another paper, this time on obese individuals, a dose of 6.4g of CLA per day resulted in a gain of 0.64kg of lean body mass over 12 weeks compared to zero significant difference in a group taking 3.2g. This is an improvement but a miniscule one, and the 6.4g group reported gastrointestinal upset throughout the trial. Finally, a one-year trial of CLA on overweight but otherwise healthy individuals resulted in an average gain of 1.8% lean body mass, Again, pretty tiny.
In overweight and obese children, a seven-month trial of CLA yielded a loss in fat mass of an average 0.5% of body fat compared to a 1.1% increase in the placebo group, barely worth mentioning in the scheme of things when you consider it’s very possible to experience significant weight loss (especially in children) by simply improving habits around food and activity. Another paper, on obese individuals, showed a statistically significant reduction in fat mass compared to placebo, but the researchers had to split the groups (placebo v CLA) into sub-groups ordered by BMI increments to find a significant difference, and even then it was a difference of 2 percent of fat mass over 12 weeks, which is very small. Finally, a six-month trial of CLA on overweight individuals found that a decrease in body fat of an average of 1kg was associated with the supplement when the researchers accounted for metabolic rate, food consumption and exercise. But it’s not all positive. The one paper I could find combining CLA and exercise showed no difference in fat loss between supplementation and placebo over 12 weeks.
Want my advice? CLA DOES improve muscle mass, but the effect is small. If you want to gain extra muscle, use your CLA money to buy some beef. Does it aid fat loss? Maybe, but keep your cash and reduce your calorie intake if you want to lose fat. It’s MUCH more effective (and reliable).