Does CLA help you lose fat?
Barely. Over 6 months or more, CLA pills beat a dummy pill by about 0.7 kg. And in small trials in obese men, both its main forms made insulin work less well.
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Does CLA help you lose fat?
A little, but not enough to matter. A review pooled 7 trials of 6 months or more in adults with overweight or obesity. People on CLA lost about 0.7 kg more weight and 1.33 kg more fat than people on a dummy pill.
The review team said the trials don’t convincingly show any clinically relevant effect. In plain words: not enough to make a real difference.
Sources: NHS; Onakpoya 2012; Namazi 2019
A second review of 13 trials found no real change in waist size. So CLA is no belly fat fix.
Your move: if you’re thinking of buying CLA, read the safety section first.
What is conjugated linoleic acid?
CLA is a group of fats. You already eat some. The main food sources are milk, dairy and meat from cows, sheep and other grazing animals.
| Where it comes from | Main form | What a small trial found |
|---|---|---|
| Milk, cheese, beef and lamb | Mostly c9t11 (over 90%) | 3 g a day of c9t11 as a pill made insulin work 15% less well. |
| CLA pills | c9t11 and t10c12, usually half and half | A 3.4 g mixed pill didn’t change blood sugar handling. t10c12 alone raised insulin resistance by 19%. |
Sources: Białek 2013; Risérus 2004; Risérus 2002
Both trials were small, in obese men with belly fat, and lasted about 3 months.
For fats with better proof behind them, see healthy fats.
How much CLA do the trials use?
Across 18 trials, the middle dose was 3.2 g a day.
| Dose or length | Fat or weight lost beyond a dummy pill |
|---|---|
| 3.2 g a day | About 0.09 kg of fat a week, across 18 trials. |
| Up to 6 months | The effect grew steadily. |
| 6 months to 2 years | The effect slowly levelled off. |
| More than 3.4 g a day | About 0.77 kg of weight, across a smaller group of trials. |
Sources: Whigham 2007; Namazi 2019
So more pills or more months don’t add up to much. The longer trials, which matter most, found about 0.7 kg.
Pairing CLA with exercise? A review of 20 trials found it lowered body fat more than exercise alone. But it didn’t help weight, fitness or blood fats.
Before you pick a dose, read the safety section below.
Is CLA safe? Side effects
The common side effects in trials were constipation, diarrhoea and soft stools.
The bigger worry is insulin, the hormone that moves sugar from your blood into your cells. When it works less well, that’s called insulin resistance.
| CLA taken | What changed against a dummy pill |
|---|---|
| t10c12, 3.4 g a day | Insulin resistance up 19%. Blood sugar up 4%. Good cholesterol (HDL) down 4%. |
| Mixed pill, 3.4 g a day | No change in weight, fat or blood sugar handling. HDL down 2%. |
| c9t11, 3 g a day | Insulin worked 15% less well. No change in body fat. |
| t10c12, 3.4 g a day | C-reactive protein (CRP), a blood sign of inflammation (the body’s response to harm), up 110%. |
Sources: Risérus 2002; Risérus 2002 (CRP); Risérus 2004
These were small trials of 25 to 60 men. The authors say the c9t11 result should be checked in larger studies that include women.
Other trials point the other way. With exercise, a review of 20 trials found CLA lowered insulin resistance and didn’t raise side effects.
More on good cholesterol: HDL cholesterol.
Liver damage is rare, but a handful of cases have been reported. One woman’s liver tests went back to normal when she stopped. Another needed a liver transplant.
What works better for fat loss?
The NHS says losing 5 to 10% of your body weight can improve your health. For someone on 90 kg, that’s 4.5 to 9 kg.
Five NHS steps to lose weight
- Eat and drink fewer calories than your body uses.
- Aim to lose 0.5 to 1 kg (1 to 2 lbs) a week.
- Get active for 45 to 60 minutes a day. You can split it into shorter sessions.
- Cut down on alcohol, which is high in calories.
- Check if you can self-refer to a local NHS weight management programme.
Source: NHS: overweight and obesity
Start with how many calories to eat. Then add protein and strength training.
Comparing other pills? See natural weight loss supplements.
When to speak to a GP
Ask for an urgent GP appointment or get help from NHS 111 if your skin or the whites of your eyes look yellow. You may also have itchy skin, darker pee and paler poo than usual.
See a GP if your BMI is in the overweight or obese range and:
- you want help to lose weight
- your waist is more than half your height
- you have a family history of obesity
- you have pre-diabetes, diabetes, high blood pressure, joint pain, high cholesterol, sleep apnoea or heart and circulation disease
- you have, or think you may have, an eating disorder such as binge eating
Have diabetes or pre-diabetes and still want to try CLA? Talk to your GP first, as small trials found it made insulin work less well. A GP can also refer you for weight management programmes, medicines or surgery.
Never stop or change a prescribed medicine without your prescriber.