Conjugated linoleic acid (CLA) often makes the headlines for its potential fat burning benefits.
In fact, some supplement companies go as far as claiming it can specifically target fat around the lower abdomen.
Whoa!
That’s pretty much the perfect supplement, right?
Sadly, the research on CLA does not support most of the claims being made, so in this comprehensive breakdown I’ll run you through what CLA is, exactly what you can expect from using it, and reveal what the latest science says regarding that so-called “fat burner” tag…
What Is CLA?
CLA is a form of dietary fat which consists of a group of healthy Omega-6 fatty acids.
You can find it in meat (especially grass-fed beef) and dairy products such as milk, but most people just supplement with it. It is believed that consuming 6-9 grams of CLA per day can improve both muscle growth and fat loss.
The key factor at play here is CLA’s ability to shut off the enzyme lipoprotein lipase. This enzyme (LPL) enables your fat cells to soak up fat from the bloodstream and store it as body fat, but if we inhibit this enzyme, we encourage the body to burn fat for fuel instead.
Therefore, CLA literally prevents the body from storing fat.
Wowza!
Interestingly, this would also mean it has a muscle sparing effect (because you are burning fat not muscle mass), making CLA a potentially very useful muscle building and fat loss supplement, I’m sure you’ll agree?!
What Does Science Say?
Ah, that’s where the good new ends.
The body of research for CLA reminds me of Rocky V.
Seriously, watch it.
The fifth Rocky installment begins quite well (much like the research on CLA, which showed huge promise in animal trials), but then Tommy Gunn is introduced (human trials in CLA) and the whole thing turns into a f**king s**t-show.
You see, we do have a small amount of research which suggests that CLA can be an effective fat loss supplement – and this is the stuff which supplement companies cite as proof of effectiveness when selling their products to you – but the problem with these studies is that they were conducted on animals. (1, 2)
Unfortunately, the results aren’t anywhere near as impressive in human trials.
Of the two human trials which do show a positive impact on weight loss, one had participants self-report their exercise activity and dietary intake (which is notoriously inaccurate) and the other did not record dietary intake at all. (3, 4)
When we look at more well-conducted trials, though, evidence suggests that CLA may not be the “fat burner” we hoped for.
During a 2008 study published in Obesity Journal, researchers showed that 12 weeks of continuous CLA supplementation led to no additional fat loss versus a simple placebo, and these findings were doubled-down on three years later in a study from Canadian researchers which was published in the Journal of Nutrition. (5, 6)
There’s even one trial which ended in fat gain! (7)
As you can see, the body of research for CLA isn’t very convincing at all!
Results appear to be wildly inconsistent from one study to the next, with the most comprehensive research saying it has no impact what-so-ever (including a 2012 meta-analysis which showed it had no effect on waist circumference, which is not exactly a badge of honour for a supplement which claims to be able to target fat around the lower abdomen!), and even when people do seem to respond the differences in weight loss results are very small! (8, 9, 10)
At the time of writing, there’s not enough proper evidence to support CLA’s reputation as a fat burner and I do not recommend using it as such. If that ever changes I will update this page to show it.
References:
- Ostrowska E., et al. Conjugated linoleic acid decreases fat accretion in pigs: evaluation by dual-energy X-ray absorptiometry. Br J Nutr (2003).
- Moya-Camarena S. Y., et al. Conjugated linoleic acid is a potent naturally occurring ligand and activator of PPARalpha. J Lipid Res (1999).
- Watras A. C., et al. The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain. Int J Obes (Lond) (2007).
- Chen S, et al. Effect of conjugated linoleic acid supplementation on weight loss and body fat composition in a Chinese population. Nutrition (2012).
- Sneddon A. A., et al. Effect of a conjugated linoleic acid and omega-3 fatty acid mixture on body composition and adiponectin. Obesity (Silver Spring) (2008).
- Joseph S. V., et al. Conjugated linoleic acid supplementation for 8 weeks does not affect body composition, lipid profile, or safety biomarkers in overweight, hyperlipidemic men. J Nutr (2011).
- Riserus U., et al. Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Am J Clin Nutr (2004).
- Rahbar A. R., et al. Effect of Conjugated Linoleic Acid as a Supplement or Enrichment in Foods on Blood Glucose and Waist Circumference in Humans: A Metaanalysis. Endocr Metab Immune Disord Drug Targets (2017).
- Onakpoya I. J., et al. The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. Eur J Nutr (2012).
- Navarro V., et al. The body fat-lowering effect of conjugated linoleic acid: a comparison between animal and human studies. J Physiol Biochem (2006).
