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Specimen PS-CLA · Grade C · 11 papers
UnclearABCD
Verdict · not backed by research

Conjugated linoleic acid (CLA)

Not worth it for fat loss and muscle gain.

Check my whole stack →
Dose3.2 g/day
WhenDaily with meals
Works afterFat loss, if any, accrued linearly for up to about 6 months in pooled trials
Evidence11 papers read

Does it work?

The label shows how strong the evidence is, not how big the effect is. Tap a claim to see its papers.

Lab note

In plain words

At 3.2 g/day, fat loss versus placebo was about 0.09 kg per week in one meta-analysis, but the largest pooled analysis found -0.44 kg fat mass overall and nothing in high-quality trials. Fat-free mass gains were about 0.27-0.3 kg, under 1%.[1][2][5]

The numbers

Fat mass change-0.44 kg70 RCTs; no change in high-quality trials[1]
Fat-free mass change+0.27 kg70 RCTs[1]
Weight change, ≥6 months-0.70 kg7 RCTs, overweight or obese[3]

Up next

Pairs with

Creatine monohydrate

What the research says about the combo →
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Next to avoidD-aspartic acidSee the verdict →

Claim by claim— each claim graded on its own

Tiny: about -0.44 kg fat mass across 70 trials, and high-quality trials showed no change in fat mass or body-fat percentage.[1][2][3][4]

Several meta-analyses report statistically significant but small effects whose clinical relevance is doubtful, and the effect disappears in high-quality studies. Weak evidence, so Grade C.

Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.

24′23′07′12′
Meta-analysis2024· Br J Nutr
The effects of conjugated linoleic acid supplementation on anthropometrics and body composition indices in adults: a systematic review and dose-response meta-analysis.

Pooling 70 RCTs (4159 people), CLA slightly reduced weight and fat and raised fat-free mass, but high-quality trials showed no fat-mass or body-fat change; effects may not be clinically important.

Studies pooled
70
Participants
4,159
Fat mass
-0.44 kg (95% CI -0.66, -0.23)
Body fat %
-0.77% (95% CI -1.09, -0.45)
pubmed.ncbi.nlm.nih.govDOI PubMed
Meta-analysis2023· Nutr Rev
Effects of conjugated linoleic acid and exercise on body composition and obesity: a systematic review and meta-analysis.

In 20 trials, CLA plus exercise lowered body fat and insulin resistance more than exercise alone but did not reduce body weight or improve exercise performance; adverse events were not increased.

Studies pooled
20
Body fat (SMD)
-0.42 (95% CI -0.70, -0.14)
Exercise performance
No benefit
Adverse events (RR)
1.32 (95% CI 0.94-1.84), not significant
pubmed.ncbi.nlm.nih.govDOI PubMed
Meta-analysis2012· Eur J Nutr
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.

In 7 trials of at least 6 months in overweight or obese people, CLA gave small weight and fat losses of uncertain clinical relevance; GI side effects were reported.

Studies pooled
7
Weight vs placebo
-0.70 kg (95% CI -1.09, -0.32)
Fat vs placebo
-1.33 kg (95% CI -1.79, -0.86)
pubmed.ncbi.nlm.nih.govDOI PubMed

Fat-free mass rose by about 0.27-0.3 kg (under 1%) in meta-analyses; trials in experienced lifters found no strength or body-composition benefit.[1][4][5][6][7]

One 7-week RCT in new trainees found extra lean mass, but a trial in experienced lifters was null and a meta-analysis found no exercise-performance benefit. Mixed and small, so Grade C.

Each plate is one paper. Taller = stronger study design, wider = more studies pooled. Tap one.

24′23′09′06′02′
Meta-analysis2024· Br J Nutr
The effects of conjugated linoleic acid supplementation on anthropometrics and body composition indices in adults: a systematic review and dose-response meta-analysis.

Pooling 70 RCTs (4159 people), CLA slightly reduced weight and fat and raised fat-free mass, but high-quality trials showed no fat-mass or body-fat change; effects may not be clinically important.

Studies pooled
70
Participants
4,159
Fat mass
-0.44 kg (95% CI -0.66, -0.23)
Body fat %
-0.77% (95% CI -1.09, -0.45)
pubmed.ncbi.nlm.nih.govDOI PubMed
Meta-analysis2023· Nutr Rev
Effects of conjugated linoleic acid and exercise on body composition and obesity: a systematic review and meta-analysis.

In 20 trials, CLA plus exercise lowered body fat and insulin resistance more than exercise alone but did not reduce body weight or improve exercise performance; adverse events were not increased.

Studies pooled
20
Body fat (SMD)
-0.42 (95% CI -0.70, -0.14)
Exercise performance
No benefit
Adverse events (RR)
1.32 (95% CI 0.94-1.84), not significant
pubmed.ncbi.nlm.nih.govDOI PubMed

All key numbers

Fat mass change-0.44 kg70 RCTs; no change in high-quality trials[1]
Fat-free mass change+0.27 kg70 RCTs[1]
Weight change, ≥6 months-0.70 kg7 RCTs, overweight or obese[3]
Body fat with exerciseSMD -0.42CLA + exercise vs exercise alone; no performance gain[4]
Insulin resistance (t10,c12 isomer)+19%obese men, 3.4 g/day for 12 weeks[9]

Evidence timeline— how the evidence built up

Meta-analysis or systematic reviewTrial or narrative review
20052010201520202025
Every paper cited on this page, placed by publication year. Hover a mark to preview it; select it to jump to the reference.

How it works

CLA is a family of isomers of linoleic acid, an omega-6 fat. In food it comes mainly from beef, lamb, milk and cheese, chiefly as the c9,t11 isomer; supplements are made with about equal c9,t11 and t10,c12. The opened sources do not quantify typical dietary intake.

In animals, mainly the t10,c12 isomer cuts fat deposition. Proposed mechanisms include lower food intake, less fat synthesis, and more energy expenditure, fat breakdown and fat oxidation. Humans respond far less than mice, and the same isomer that drives fat loss in animals raised insulin resistance in obese men.[5][8][9]

References

Reviewed 03 Oct 2026 · every PubMed ID checked against PubMed

  1. [1]Asbaghi O, et al. The effects of conjugated linoleic acid supplementation on anthropometrics and body composition indices in adults: a systematic review and dose-response meta-analysis. Br J Nutr. 2024;131(3):406-428. Meta-analysis PubMed · DOI
  2. [2]Whigham LD, et al. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr. 2007;85(5):1203-11. Meta-analysis PubMed · DOI
  3. [3]Onakpoya IJ, 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;51(2):127-34. Meta-analysis PubMed · DOI
  4. [4]Liang CW, et al. 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. Meta-analysis PubMed · DOI
  5. [5]Schoeller DA, et al. A meta-analysis of the effects of conjugated linoleic acid on fat-free mass in humans. Appl Physiol Nutr Metab. 2009;34(5):975-8. Meta-analysis PubMed · DOI
  6. [6]Pinkoski C, et al. The effects of conjugated linoleic acid supplementation during resistance training. Med Sci Sports Exerc. 2006;38(2):339-48. Randomized trial PubMed · DOI
  7. [7]Kreider RB, et al. Effects of conjugated linoleic acid supplementation during resistance training on body composition, bone density, strength, and selected hematological markers. J Strength Cond Res. 2002;16(3):325-34. Randomized trial PubMed
  8. [8]Wang Y, Jones PJ. Dietary conjugated linoleic acid and body composition. Am J Clin Nutr. 2004;79(6 Suppl):1153S-1158S. Review PubMed · DOI
  9. [9]Risérus U, et al. Treatment with dietary trans10cis12 conjugated linoleic acid causes isomer-specific insulin resistance in obese men with the metabolic syndrome. Diabetes Care. 2002;25(9):1516-21. Randomized trial PubMed · DOI
  10. [10]Mirzaii S, et al. Association of conjugated linoleic acid consumption and liver enzymes in human studies: A systematic review and meta-analysis of randomized controlled clinical trials. Nutrition. 2016;32(2):166-73. Meta-analysis PubMed · DOI
  11. [11]Cornish SM, et al. Conjugated linoleic acid combined with creatine monohydrate and whey protein supplementation during strength training. Int J Sport Nutr Exerc Metab. 2009;19(1):79-96. Randomized trial PubMed · DOI

Dose

3.2 g/day was the median dose in a meta-analysis; trials used about 3-6 g/day

  1. Per gram per week

    Fat loss vs placebo of -0.024 kg per g CLA per week.[2]

  2. 3.2 g/day

    Modest fat loss, about 0.09 kg/week vs placebo.[2]

  3. 5 g/day, 7 weeks with training

    +1.4 vs +0.2 kg lean tissue in mostly novice trainees.[6]

  4. 6 g/day, 28 days with training

    No significant change in experienced lifters.[7]

Which form?— hover or tap

50:50 c9,t11 / t10,c12 mixtureBest studied

The usual commercial product; did not change glucose metabolism but lowered HDL by 2% in obese men.[8][9]

Purified t10,c12 isomerWorse

Increased insulin resistance by 19% and lowered HDL by 4% in obese men.[9]

CLA-enriched foodsUnknown

Did not significantly raise AST, unlike supplements.[10]

Who benefits

Benefit more
  • People with BMI ≥25, women and those supplementing longer than 4 weeks (subgroups in an exercise meta-analysis)
  • Novice trainees in one 7-week RCT
Benefit less
  • Experienced resistance-trained athletes
  • Anyone judged by high-quality trials only

Sources[1][4][6][7]

Stacking

+Creatine + whey protein

CLA plus creatine plus whey beat whey alone or creatine plus whey for strength and lean mass over 5 weeks, but CLA alone was not tested.[11]

+Exercise

Lowered body fat a little more than exercise alone but did not improve performance.[4]

In food

FoodAmount
Beef, lamb, milk and cheeseMain dietary source (amount not quantified in opened sources)[8]

Safety

Caution
CLA with exercise did not increase adverse events in a meta-analysis, but GI complaints are common. The t10,c12 isomer increased insulin resistance by 19% in obese men, and supplements slightly raised the liver enzyme AST.
Possible side effects
  • Constipation, diarrhoea and soft stools
  • Small HDL-cholesterol drop
  • Raised insulin resistance with the t10,c12 isomer in obese men
  • Slight rise in AST
Talk to a doctor first if
  • You have diabetes, prediabetes or metabolic syndrome
  • You have liver disease
  • You are pregnant or breastfeeding
Lab note
Buy products certified by Informed Sport, Informed Choice or NSF Certified for Sport. Supplements can contain things that aren’t on the label.

Myths vs research— scroll through

Myth

CLA burns belly fat

What the research says

High-quality trials show no change in fat mass or body-fat percentage.[1]

Myth

It works in people like it does in mice

What the research says

Humans are not as responsive as mice; the fat-free mass gain was under 1%.[5]

Myth

It improves insulin sensitivity

What the research says

The t10,c12 isomer increased insulin resistance by 19% in obese men.[9]

FAQ

Unlikely to be noticeable: pooled fat loss is under half a kilogram and absent in high-quality trials.[1]

Adverse events were not increased in exercise trials, but GI upset is common, AST rises slightly, and one isomer worsened insulin resistance in obese men.[3][4][9][10]

Yes, mainly from beef, lamb and dairy, chiefly as the c9,t11 isomer.[8]

  • Grades are judged for healthy adults who train; most fat-loss trials were in overweight or obese adults.
  • Kreider 2002 had 23 participants over 28 days, so it was small and short; funding is not disclosed in the abstract.
  • Cornish 2009 tested CLA only in combination with creatine and whey, so its benefit cannot be attributed to CLA.
  • Whigham 2007 numbers are adjusted to the median 3.2 g/day dose.
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