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CLA (conjugated linoleic acid)

A fat-loss favourite with modest, inconsistent results — and reasons for caution at high doses.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsFatty acidsBody composition

CLA is a naturally occurring fatty acid (found in dairy and beef) sold as a body-composition aid. The marketing is confident; the data are lukewarm.

Key takeaways

  • Meta-analyses show CLA produces a small reduction in body fat (around 3.2 g/day), often not clinically meaningful.1
  • High-quality trials tend to show little or no effect.
  • High doses may worsen insulin sensitivity or lipids in some people.
  • Not a reliable slimming aid — diet and training matter far more.

What it is

A group of isomers of the omega-6 fat linoleic acid, naturally present in ruminant meat and dairy; supplements are made from vegetable oils.

The evidence

Pooled analyses find a statistically significant but small loss of fat mass, which the authors themselves note may not be clinically important, and high-quality studies often show no benefit.1 Some data raise concerns about metabolic side effects at higher doses.

Dose & safety

Studies use ~3–4 g/day. Given the weak benefit and possible downsides, it’s low on the priority list; monitor if you have metabolic risk factors.

Who benefits

Realistically few — the effect is small and unreliable. Effort is better spent on diet, protein and training.

Bottom line: a much-hyped fat-loss aid with a small, unreliable effect and some safety caveats — not worth prioritising over the basics.

References

Adult research summary for education, not a prescription.

  1. Whigham LD, et al. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 2007. www.sciencedirect.com

This article summarises nutrition science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.