In 30 seconds
- You will not notice CLA within days: it contains no stimulants and its effect is measured in body fat, over weeks and months.
- In a meta-analysis of 18 trials, 3.2 g a day led to 0.09 kg more fat lost per week than placebo: about 1.1 kg at 12 weeks, according to its authors.
- The first changes were measured at 4 weeks, in abdominal diameter, and at 30 days alongside a diet. The effect grew linearly up to 6 months.
- EFSA considers 3-3.5 g of CLA a day safe for 6 months: a plan of 12 weeks to 6 months fits with the studies.
CLA takes weeks to show, not days. In the studies, the first changes were measured at 4 weeks and the effect on fat grew linearly up to 6 months 1 2. With 3.2 g a day, the expected difference at 12 weeks is about 1.1 kg of fat compared with placebo 1. The full answer, with dose and timing, is in what CLA is good for.
Here is what was measured at each stage, why you sometimes do not notice it and how long to take it for.
Why you do not notice it within days
CLA is not a stimulant: it contains no caffeine or synephrine. You will not feel anything like your morning coffee: no energy rush, no warmth, no faster pulse. We compare it with the stimulant-based ones in fat burners: which ones work, according to the studies.
Its territory is body fat. Researchers suggest that it helps release fat from its stores so the muscles can use it for energy, and that it slows down the formation of new fat 3. These are processes measured in body composition, not in how you feel an hour later.
That is why CLA trials last weeks or months. Most last 12 weeks, and they range from 28 days to 2 years 1.
Week by week
When the changes with CLA were measured
The CLA timeline, according to the studies
| When | Study | What was measured with CLA and with placebo |
|---|---|---|
| 4 weeks | 25 men with abdominal obesity, 4.2 g a day | Abdominal diameter fell more than with placebo |
| 30 days | 14 women on a low-calorie diet, 3 g a day | 2.7% less body fat; with placebo, fat had not yet fallen |
| 12 weeks | 63 adults with overweight or obesity, 3.4 g a day | With CLA, 0.69 kg less weight and 0.49 kg less fat than at the start; with placebo, 0.09 kg and 0.1 kg, with no significant change |
| 12 weeks | Meta-analysis of 18 trials, 3.2 g a day | About 1.1 kg more fat lost than with placebo |
| 6 months or more | Meta-analysis of 7 trials | 1.33 kg less fat and 0.7 kg less weight |
| 1 year | 180 overweight adults, 3.4-3.6 g a day | Between 6.9% and 8.7% less fat mass |
Sources: Risérus et al., 2001; Carvalho et al., 2012; NIH Office of Dietary Supplements; Whigham et al., 2007; Onakpoya et al., 2012; Gaullier et al., 2004.
At 4 weeks: the abdomen
This is the first change measured. In one trial, 25 men aged 39 to 64 with abdominal obesity took 4.2 g of CLA a day for 4 weeks. Their abdominal diameter fell more than with placebo 2.
At that point, the other measurements were not yet different from placebo 2. If your waist is your main concern, we cover it in belly fat: can you lose fat from one specific area?.
At 30 days, with a diet
Another trial followed 14 sedentary women with metabolic syndrome for 90 days. All of them followed a low-calorie diet, some with 3 g of CLA a day and the others with placebo 4.
With CLA, body fat had already dropped at 30 days, by 2.7%, and by 3.3% at 90 days. With placebo, it only dropped at 90 days, by 2.0% 4.
At 12 weeks: the first check-in
It is the most common trial length 1. In one trial with 63 adults with overweight or obesity, 3.4 g of CLA a day led to 0.69 kg less weight and 0.49 kg less fat. The placebo group lost just 0.09 kg of weight 3.
The meta-analysis of 18 trials calculated, with 3.2 g a day, 0.09 kg more fat lost per week than with placebo. According to its authors, the expected difference at 12 weeks is 1.1 kg 1.
From 6 months to 2 years
The effect grew linearly up to 6 months. After that, it gradually approached a ceiling, at around 2 years 1.
In trials lasting 6 months or more, the difference was 1.33 kg of fat and 0.7 kg of weight compared with placebo 5. And in a one-year trial with 180 overweight adults eating normally, fat mass ended up between 6.9% and 8.7% lower than in the placebo group 6.
What brings results forward
CLA works best when the rest of your plan is already in place:
- With a diet: in the trial with 14 women, fat dropped at 30 days with CLA and at 90 days with placebo 4.
- With exercise: a meta-analysis pooled 20 trials that compared CLA plus exercise with exercise alone. With CLA, body fat fell more 7.
- With a little patience: in that meta-analysis, the effect was significant in interventions lasting more than 4 weeks, in women and with a BMI of 25 or more 7.
The foundation is always the same: a moderate deficit, protein at every meal, strength training and good rest. Work out your calories with the calorie deficit calculator and find the full plan in the fat-loss guide.
Why you sometimes do not notice it
0.09 kg of fat a week is a gradual change: you will not see it in the mirror from one day to the next. The meta-analysis authors explain it themselves: to detect a 1.1 kg difference at 12 weeks, you need about 44 participants per group 1. In their view, many trials without a clear result were too small to see it 1.
In your case, the key is to measure it properly:
- Your waist, every two weeks, at the same time of day and before breakfast.
- Your weekly average on the scales, not a single day's reading.
- A photo when you start and every 4 weeks, in the same light.
- Your clothes: how your usual trousers fit.
How long to take it for
- At least 12 weeks, the length of most trials 1.
- Up to 6 months in a row. EFSA considers 3-3.5 g of CLA a day safe for 6 months; beyond that, it has not established its safety 8. If you want to continue, check with your doctor.
- Every day, without gaps. One softgel with each main meal. If you forget one, do not take two at the next meal.
You will find the full schedule in how to take CLA and all the trials in CLA: what the studies say.
If you are pregnant or breastfeeding, have diabetes or take medication, check with your doctor first.
Frequently asked questions
How long does CLA take to work?
Studies measure it in weeks and months. The first changes were measured at 4 weeks and, according to the meta-analysis of 18 trials, the expected difference at 12 weeks is about 1.1 kg of fat compared with placebo, with 3.2 g a day.
Do you feel CLA as soon as you take it?
No. It contains no caffeine or other stimulants, so you will not feel anything like a coffee. Its effect is measured in body fat, over weeks.
How long do you need to take CLA to see results?
Most trials lasted 12 weeks, and the effect on fat grew linearly up to 6 months. EFSA considers 3-3.5 g a day safe for 6 months.
Why can't I notice CLA working?
Because the change is gradual: about 0.09 kg of fat per week compared with placebo in the studies. Measure your waist every two weeks instead of checking the mirror every day, and combine it with a moderate deficit, protein and strength training.
Does CLA work faster with diet and exercise?
In a trial with 14 women on a diet, fat had already dropped at 30 days with CLA and only at 90 days with placebo. And in a meta-analysis of 20 trials, CLA with exercise reduced fat more than exercise alone.
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
- Risérus U, Berglund L, Vessby B. Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial. Int J Obes Relat Metab Disord. 2001;25(8):1129-1135. View publication
- Office of Dietary Supplements, National Institutes of Health. Dietary supplements for weight loss: fact sheet for health professionals. View publication
- Carvalho RF, Uehara SK, Rosa G. Microencapsulated conjugated linoleic acid associated with hypocaloric diet reduces body fat in sedentary women with metabolic syndrome. Vasc Health Risk Manag. 2012;8:661-667. 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
- Gaullier JM, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H, Gudmundsen O. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr. 2004;79(6):1118-1125. View publication
- Liang CW, Cheng HY, Lee YH, Liou TH, Liao CD, Huang SW. Effects of conjugated linoleic acid and exercise on body composition and obesity: a systematic review and meta-analysis. Nutr Rev. 2023;81(4):397-415. 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.
