In 30 seconds
- CLA is a group of forms of linoleic acid. It is found naturally in milk and meat from ruminants, and supplements obtain it from vegetable oils such as safflower oil.
- Meta-analyses find more fat loss than with placebo: about 0.09 kg a week with 3.2 g a day.
- In studies lasting 6 months or more, the difference was 0.7 kg of body weight and 1.3 kg of fat compared with placebo.
- EFSA considers 3-3.5 g a day for 6 months to be safe: the same amount used in the studies.
CLA is one of the fat-loss supplements with the most trials behind it. Here is what the meta-analyses and the European Food Safety Authority say, study by study and with their figures. If you are after the practical answer, with dose and timing, you will find it in what CLA is good for.
What CLA is
CLA stands for conjugated linoleic acid. It is not a single substance but a group of forms of linoleic acid, an omega-6 fatty acid, in which the double bonds are arranged differently. The two most studied are known by their structure: cis-9, trans-11 and trans-10, cis-12.
It is found naturally, in small amounts, in milk, cheese and meat from ruminants. Supplements obtain it from vegetable oils, such as safflower oil, which are processed to concentrate the CLA.
Level of evidence by outcome
| Outcome | Evidence | What the data show |
|---|---|---|
| Body fat | Low | 0.09 kg less fat per week compared with placebo in 18 trials. |
| Body weight | Low | 0.7 kg less than with placebo in studies lasting 6 months or more. |
The rating is our own, based on the number of studies, their quality and the consistency of the results.
The key studies
| Study | Type | Sample | Outcome |
|---|---|---|---|
| Whigham et al., 2007 | Meta-analysis | 18 placebo-controlled trials | With 3.2 g a day, 0.09 kg less fat per week than with placebo. 1 |
| Onakpoya et al., 2012 | Meta-analysis | 7 trials lasting 6 months or more | −0.7 kg of body weight and −1.3 kg of fat compared with placebo, in the longer studies. 2 |
| EFSA, 2012 | Safety assessment | CLA-rich oils | Safe at 3-3.5 g a day for 6 months. 3 |
The meta-analyses
CLA versus placebo: the figures
Body fat: what the meta-analyses found
Whigham's meta-analysis brought together 18 placebo-controlled trials and calculated that, with 3.2 g of CLA a day, people lose 0.09 kg more fat per week than with placebo. 1
Onakpoya's focused on the longer studies, lasting 6 months or more, in people with overweight or obesity. It found 0.7 kg less body weight and 1.3 kg less fat than with placebo 2.
Amount a day
The dose in the studies and the amount EFSA considers safe
What EFSA says about its safety
The European Food Safety Authority considers 3-3.5 g of CLA a day for 6 months to be safe 3: the same amount used in the studies.
Side effects
In the longer trials, constipation, diarrhoea and loose stools were described 2. It is not recommended during pregnancy or breastfeeding unless advised by a health professional, and if you have diabetes or take medication, check with your doctor first.
Frequently asked questions
What is CLA?
It is the name of a group of forms of linoleic acid, an omega-6 fatty acid, in which the double bonds are in a different position. It is found naturally in milk, cheese and meat from ruminants, and supplements obtain it from vegetable oils such as safflower oil.
Does CLA help you lose fat?
Meta-analyses find more fat loss than with placebo: about 0.09 kg a week with 3.2 g a day, and 1.3 kg of fat in studies lasting 6 months or more. Pair it with your diet and your training.
How much CLA is taken in the studies?
The reference dose in the most cited meta-analysis is 3.2 g a day. EFSA assessed 3-3.5 g a day as safe for up to 6 months.
Does CLA have side effects?
In the longer trials, digestive discomfort was described, such as constipation, diarrhoea or loose stools. EFSA considers it safe at 3-3.5 g a day for 6 months. If you have diabetes or take medication, check with your doctor first.
Who should not take CLA?
It is not recommended during pregnancy or breastfeeding unless advised by a health professional. If you have diabetes, take medication or have any health condition, check with your doctor first.
How long did the CLA trials last?
From 4 weeks to a year. The meta-analysis of 18 trials saw the effect on fat grow up to 6 months, and the studies of 6 months or longer are the ones that measure the 1.3 kg difference in fat versus placebo. That is why CLA is judged in months, not weeks.
Sources
- Whigham LD, Watras AC, Schoeller DA. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr. 2007;85(5):1203-1211. View publication
- Onakpoya IJ, Posadzki PP, Watson LK, Davies LA, Ernst E. 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;51(2):127-134. View publication
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Statement on the safety of the «conjugated linoleic acid (CLA)-rich oils» Clarinol® and Tonalin® TG 80 as novel food ingredients. EFSA Journal. 2012;10(5):2700. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product. A varied and balanced diet and a healthy lifestyle are important.
