CLA

Does it work?

• -Mostly no. Across the biggest meta-analyses CLA does "work" in the statistical sense — but the effect is tiny: roughly 0.05 kg of fat per week at full dose, and in the highest-quality trials even that disappears. It's real biochemistry with results too small to notice in the mirror, and the active isomer comes with a metabolic catch.

The catch

• -The headline meta-analyses report fat loss of about 0.05 kg/week vs placebo at ~3.2 g/day — a few hundred grams over months, on the edge of measurement error.
• -When reviewers isolate only the high-quality, low-bias trials, the effect on fat mass and body-fat percent vanishes. The 'significant' result is largely carried by weaker studies.
• -Even the positive findings are statistically real but clinically meaningless — authors of the long-term review concluded CLA produces no clinically relevant change in body composition.

Better option

• -Put the money toward hitting a daily protein target and a modest calorie deficit — and if you want a stimulant edge, caffeine does more for fat loss than CLA ever will.

Safety

• -The active trans-10,cis-12 isomer raised insulin resistance and oxidative-stress and inflammation markers (CRP) in obese men with metabolic syndrome — the opposite of what you want.
• -Commonly causes GI side effects: nausea, loose stools, and upset stomach.
• -If you have type 2 diabetes, insulin resistance, or metabolic syndrome, skip it — talk to your doctor before using CLA.

Key research

• Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humansAm J Clin Nutr · 2007 · Meta-analysis
• A meta-analysis of the effects of conjugated linoleic acid on fat-free mass in humansAppl Physiol Nutr Metab · 2009 · Meta-analysis
• 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 trialsEur J Nutr · 2012 · Meta-analysis
• The effects of conjugated linoleic acid supplementation on anthropometrics and body composition indices in adults: a systematic review and dose-response meta-analysisBr J Nutr · 2024 · Meta-analysis

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