Research

Hormonal

The 10,12 CLA isomer is primarily responsible for the fat-loss effects in animal models but causes insulin resistance in humans, whereas the 9,11 isomer may have different metabolic effects.

Most CLA supplements contain a mix of isomers, but the 10,12 isomer is the one that reduces fat in animals but causes insulin resistance in humans. If you take CLA, you are likely consuming this isomer, which may harm your metabolic health.

GoodQualifiesHIGH confidence
It was later determined that the active CLA isomer responsible for reducing adiposity was 10,12 CLA... further studies by this group also showed, for the first time, that the 10,12 CLA isomer could promote insulin resistance.
Laura den Hartigh · Nutrients · 2019

Why this rating

The paper clearly distinguishes between isomers and cites multiple studies showing the specific effects of 10,12 CLA on insulin resistance.

Source

Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives

Laura den Hartigh · Nutrients · 2019

DOI 10.3390/nu11020370

narrative_reviewCited 367×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

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