What the evidence says. Graded mixed: meta-analyses do find statistically significant fat loss, but the magnitude is trivial (~0.7 kg weight, ~1.3 kg fat over months) and vanishes in high-quality studies, while the t10,c12 isomel can worsen insulin resistance and oxidative stress. (Mixed evidence: Conflicting results across studies; benefit uncertain.)
What is CLA?
CLA (Conjugated Linoleic Acid) is a heart and metabolic supplement used for marketed for fat loss. NutriDex grades the human evidence as Mixed. CLA is a group of linoleic-acid isomers found naturally in dairy and beef and sold as a fat-loss supplement, usually as a roughly 50:50 mix of the cis-9,trans-11 and trans-10,cis-12 forms. Pooled randomized trials do show a real but tiny effect: roughly 0.5–0.9 kg less body weight and about 1.3 kg less fat versus placebo over several months. A 2024 dose-response meta-analysis found fat mass fell only ~0.44 kg, and the effect on fat mass and body-fat percentage disappeared when analysis was limited to high-quality trials. Meta-analyses show no benefit on cholesterol, blood pressure, or HbA1c, and some report a small rise in fasting glucose. The trans-10,cis-12 isomer specifically has been shown to raise insulin resistance and oxidative-stress markers in men with metabolic syndrome. Overall the weight benefit is too small to matter clinically, and the metabolic signals are a genuine concern.
Purported Benefits
✓Marketed for fat loss
✓Slight body-fat reduction
✓Body-recomposition claims
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
Outcome
Evidence
Effect
Studies
Body fat / weight lossMeta-analyses show a real but tiny loss (~0.4-1.3 kg fat) that vanishes in high-quality trials; not clinically meaningful.
Mixed
↔ mixed · negligible
4
Lipids and blood pressureGRADE meta-analysis in cardiovascular-risk patients found no effect on lipids or blood pressure.
Common side effects are GI: nausea, loose stools, diarrhea and indigestion. The trans-10,cis-12 isomer can worsen insulin resistance, raise fasting glucose, lower HDL and increase oxidative-stress and inflammatory markers, so caution is warranted in diabetes, prediabetes and metabolic syndrome, and CLA may oppose antidiabetic medication. Rare reports of liver injury exist; avoid in liver disease and stop for jaundice or dark urine. Safety in pregnancy and breastfeeding is not established. Educational only — always check with your doctor or pharmacist before combining CLA with any medicine.
CLA is most often taken for Marketed for fat loss, Slight body-fat reduction, Body-recomposition claims. Popular fat-loss fatty acid whose real-world effect is tiny.
Does CLA work — what does the evidence say?
Mixed evidence. Conflicting results across studies; benefit uncertain. CLA is a group of linoleic-acid isomers found naturally in dairy and beef and sold as a fat-loss supplement, usually as a roughly 50:50 mix of the cis-9,trans-11 and trans-10,cis-12 forms. Pooled randomized trials do show a real but tiny effect: roughly 0.5–0.9 kg less body weight and about 1.3 kg less fat versus placebo over several months. A 2024 dose-response meta-analysis found fat mass fell only ~0.44 kg, and the effect on fat mass and body-fat percentage disappeared when analysis was limited to high-quality trials. Meta-analyses show no benefit on cholesterol, blood pressure, or HbA1c, and some report a small rise in fasting glucose. The trans-10,cis-12 isomer specifically has been shown to raise insulin resistance and oxidative-stress markers in men with metabolic syndrome. Overall the weight benefit is too small to matter clinically, and the metabolic signals are a genuine concern.
What is the typical dose of CLA?
Trials use 3.2–6.4 g/day of a ~50:50 c9,t11/t10,c12 isomer mix, taken with meals.
Is CLA safe? Any cautions or side effects?
Common side effects are GI: nausea, loose stools, diarrhea and indigestion. The trans-10,cis-12 isomer can worsen insulin resistance, raise fasting glucose, lower HDL and increase oxidative-stress and inflammatory markers, so caution is warranted in diabetes, prediabetes and metabolic syndrome, and CLA may oppose antidiabetic medication. Rare reports of liver injury exist; avoid in liver disease and stop for jaundice or dark urine. Safety in pregnancy and breastfeeding is not established.
How many studies support CLA?
NutriDex cites 9 sources for CLA, graded "Mixed".
Cite this page
APA
Peh, D. (2026). CLA (Conjugated Linoleic Acid): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 16 Sept 2026, from https://nutridex.info/s/cla
BibTeX
@misc{nutridex_cla,
author = {Peh, Daryl},
title = {CLA (Conjugated Linoleic Acid): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/cla},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.