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C Little evidence · Weight Management

CLA (Conjugated Linoleic Acid)

Also known as: conjugated linoleic acid, CLA softgels

CLA is a fatty acid sold for fat loss, but human studies show only a tiny effect on body fat. Research has used about 3–4 g per day; potential metabolic side effects are a concern.

Why grade C?

Graded C because meta-analyses show CLA produces at most a very small reduction in body fat in humans, far less than early animal studies suggested, and some studies raise concerns about insulin sensitivity and blood lipids with the trans-10, cis-12 isomer.

Dose calculator

kg
Typical study dose (effect very small)
Fixed dose, independent of body weight
3–4 g

Doses mirror ranges used in published research — they are not a personal prescription.

At a Glance

CLA (Conjugated Linoleic Acid)
EvidenceC
RatingLittle evidence
CategoryWeight Management
Typical study dose (effect very small)3–4 g
Food sourcesBeef and lamb, especially grass-fed, Milk, butter and cheese from grazing animals
Side effects listed3

Grades follow the style of the Australian Institute of Sport Sports Supplement Framework. Summary of published research, not advice.

How it works

CLA refers to a group of linoleic acid isomers found naturally in meat and dairy from grazing animals. Supplements are made from vegetable oils and contain a mix of the cis-9, trans-11 and trans-10, cis-12 isomers. In animal studies, the trans-10, cis-12 isomer reduced fat storage, possibly by affecting enzymes involved in fat metabolism. In humans, the effects are much smaller, averaging around 0.1 kg of fat loss per week in one meta-analysis — an effect many researchers consider too small to matter in practice.

What research supports

  • Very small reduction in body fat in some human studies, averaging around 0.1 kg per week in a meta-analysis
  • No consistent effect on body weight, lean mass or performance

Dosage

Human studies commonly use about 3–4 g of mixed CLA isomers per day for weeks to months.

Timing

Studies typically split doses with meals. No timing strategy has been shown to enhance effects.

Side effects

  • Stomach upset, nausea and loose stools
  • Some studies report reduced insulin sensitivity and unfavourable changes in blood lipids, mainly with the trans-10, cis-12 isomer
  • Fatty liver has been reported in animal studies

Cautions

  • People with diabetes, insulin resistance, liver conditions or high cholesterol should consult a doctor before use
  • May interact with blood thinners
  • Athletes subject to anti-doping rules should only use products certified by an independent third-party testing program for banned substances; certification lowers, but does not eliminate, the risk of contamination.

Food sources

Beef and lamb, especially grass-fed, Milk, butter and cheese from grazing animals.

Frequently asked questions

Does CLA burn belly fat?

Human research shows at most a very small overall reduction in body fat, and there is no evidence it targets abdominal fat specifically.

Is CLA safe?

It is generally tolerated, but some studies report negative effects on insulin sensitivity and blood lipids, so it is not risk-free.

Is CLA a healthy fat?

Naturally occurring CLA in dairy and meat is found in small amounts. Supplements contain different isomer ratios and should not be considered equivalent to food sources.

Sources & further reading

  1. Whigham LD, Watras AC, Schoeller DA. (2007). Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans . Am J Clin Nutr
  2. NIH Office of Dietary Supplements (2022). Dietary Supplements for Weight Loss: Fact Sheet for Health Professionals . National Institutes of Health