CLA (Conjugated Linoleic Acid): The Science of Fat Reduction

What Is CLA and How Does It Differ From Regular Linoleic Acid?

CLA, or conjugated linoleic acid, is a naturally occurring fatty acid found primarily in the meat and milk of ruminants (cows, sheep, goats). Despite its name, CLA differs significantly from regular linoleic acid (an omega-6 fatty acid) — their chemical structures are different, and this has major biological consequences.

CLA actually consists of 28 different isomers, but the two main biologically active forms are:

• cis-9, trans-11 CLA (c9,t11) — makes up approximately 75–90% of natural CLA; the primary form in dairy and meat
• trans-10, cis-12 CLA (t10,c12) — makes up approximately 3–5% of natural CLA; the primary fat-loss-promoting isomer

This distinction matters: supplements typically contain a 50:50 mixture of both isomers, meaning you get much more t10,c12 than from food alone.

Why Has Interest in CLA Grown?

CLA gained attention in 1987 when Michael Pariza discovered that a substance found in grilled meat inhibited cancer cell growth. Since then, CLA's diverse effects have been identified:

• Body fat reduction — the most studied and marketed effect
• Muscle preservation — body composition improvement
• Anti-inflammatory effects — moderate immune system impact
• Insulin sensitivity improvement — mixed evidence

But as always, reality is more complex than marketing messages.

Does CLA Really Help Reduce Fat?

Scientific Evidence in Humans

CLA is one of the most studied fat loss supplements. Results exist, but expectations need to be realistic.

Whigham et al. (2007) — meta-analysis:

• Analyzed 18 studies
• CLA reduced body fat by an average of 0.09 kg per week, or about 90 grams per week
• This translates to approximately 1.2 kg of fat in 3 months
• Dose: 3.2 g CLA per day

Onakpoya et al. (2012) — Cochrane-style review:

• Analyzed 15 studies, 818 participants
• CLA reduced body fat by 1.33 kg more than placebo (average follow-up 6 months)
• The effect was statistically significant but clinically modest

Blankson et al. (2000):

• 60 overweight individuals, 12 weeks
• 3.4 g CLA daily vs placebo
• CLA group lost 1.7 kg more body fat
• Muscle mass was better preserved in the CLA group

What Do These Numbers Actually Mean?

Realistic expectations:

• Adding CLA alongside diet and training yields approximately ~1–2 kg of additional fat loss over 3–6 months
• This is not a miracle solution — the effect is moderate
• CLA works better combined with diet and training, not independently
• The effect is greater in overweight individuals than in normal-weight ones

How Does CLA Work in the Body?

CLA affects body fat through multiple mechanisms:

Affecting Fat Metabolism

1. Inhibiting lipoprotein lipase (LPL) — LPL is an enzyme that helps transport fatty acids into fat cells. CLA reduces its activity, meaning less fat is stored in fat cells.

2. Increasing fatty acid oxidation — CLA activates the CPT-1 (carnitine palmitoyltransferase-1) enzyme, which transports fatty acids into mitochondria for burning.

3. Promoting apoptosis in fat cells — some studies show CLA may promote programmed death of fat cells, reducing fat cell count.

4. Increasing energy expenditure — CLA may modestly increase UCP-2 (uncoupling protein 2) expression, converting some energy to heat.

Muscle Preservation

One of CLA's most interesting properties is its ability to preserve muscle mass during a calorie deficit:

• CLA may stimulate protein synthesis in muscle tissue
• It inhibits muscle protein breakdown (proteolysis)
• The effect is particularly important during dieting, when muscle loss is a risk

What CLA Dose and Form Is Most Effective?

Optimal Dosing

Important: Doses below 3 g per day have not been effective in most studies.

When and How to Take?

• Split the dose across 2–3 meals — absorbs better with food
• Do not take on an empty stomach — may cause digestive issues
• Consistency is key — effects appear only after 8–12 weeks
• Do not expect quick results — CLA is not a rapid fat loss tool

CLA Forms

Triglyceride (TG) form:

• More natural — resembles CLA from food
• Some studies show better absorption
• Usually more expensive

Free fatty acid (FFA) form:

• The most studied form
• Good bioavailability
• More affordable

Ethyl ester form:

• Less studied
• Bioavailability may be lower
• Least expensive

Recommendation: choose TG or FFA form containing a 50:50 mixture of c9,t11 and t10,c12 isomers.

Does CLA Have Side Effects?

CLA is generally safe at moderate doses, but some concerns deserve attention.

Known Side Effects

Gastrointestinal issues (most common):

• Diarrhea, nausea, bloating — especially when starting
• Usually diminish within 1–2 weeks
• Taking with food helps reduce them

Fatty liver (concerning):

• Some animal studies show the t10,c12 isomer may promote fatty liver
• In human studies, this effect has been much weaker than in animals
• Ricard et al. (2007) found that 6.4 g CLA daily for 12 weeks did not cause clinically significant fatty liver
• Still, caution is sensible for people with liver conditions

Insulin resistance:

• Some studies show the t10,c12 isomer may increase insulin resistance
• The effect has been inconsistent across studies
• Diabetics should consult their doctor before using CLA

Inflammatory markers:

• Mixed results — some studies show increases, others decreases
• Long-term effects need more research

Is CLA Beneficial for Athletes?

Athletes are one of CLA's primary target groups, and there are some good reasons:

Potential benefits for athletes:

• Body composition improvement — fat reduction + muscle preservation
• Dieting period support — helps preserve muscle mass in a calorie deficit
• Recovery support — moderate anti-inflammatory effect

Studies among athletes:

Pinkoski et al. (2006):

• 76 individuals beginning resistance training
• 5 g CLA daily vs placebo, 7 weeks
• CLA group lost more fat and preserved more muscle mass
• Strength measures were similar

Lowery et al. (1998):

• Experienced resistance trainers
• 7.2 g CLA daily, 6 weeks
• CLA group showed better body composition changes

Practical recommendation for athletes:

• 3.4–6.4 g CLA daily when focusing on body composition
• Split across 3 meals
• Combine with a calorie deficit for best results
• Do not expect miraculous results — the effect is moderate but consistent

Summary: A Practical Guide to Using CLA

CLA is one of the better-studied fat loss supplements, but realistic expectations are important:

What CLA does:

• Helps reduce body fat by 1–2 kg over 3–6 months (alongside diet and training)
• Helps preserve muscle mass during a calorie deficit
• Positively affects body composition

What CLA does NOT do:

• Does not replace healthy nutrition or training
• Does not cause dramatic fat loss
• Does not work independently without a calorie deficit

Practical plan:

1. Start with 3.0–3.4 g CLA daily
2. Split the dose across 3 meals
3. Use for at least 12 weeks to see results
4. Choose TG or FFA form
5. Combine with moderate calorie deficit and regular training

Combine with effective supplements:

• L-carnitine selection — fat transport support
• Omega-3 selection — inflammation reduction and heart health
• B-vitamin selection — energy production support

Browse our store selection and find the right supplements to support your body composition goals.

Can CLA Also Prevent Fat Regain?

One of CLA's most interesting properties is its potential to prevent weight regain after dieting.

CLA and Weight Regain

Whigham et al. (2004) studied 54 overweight individuals who had lost weight. With 3.4 g CLA vs placebo for 12 months, the CLA group increased fat-free mass and did not regain as much fat. This suggests CLA may help prevent weight regain.

CLA Food Sources

CLA is also found in food. Lamb contains 5.6 mg per gram of fat. Grass-fed beef contains 3.1–8.0 mg, which is 2–3 times more than grain-fed beef. Whole milk contains 5.5 mg, butter 4.7 mg, and yogurt 4.8 mg per gram of fat.

CLA and Body Composition Monitoring

When using CLA, measure results correctly. Weight alone is insufficient since CLA can simultaneously reduce fat and increase muscle mass. Body fat percentage is a better metric. Waist circumference is a simple tracking method. Take photos regularly and measure every 4 weeks.

Frequently Asked Questions About CLA

How quickly does CLA show results? CLA's effect is slow and moderate. Initial body composition changes appear after 8–12 weeks. Do not expect visible results in the first few weeks.

Does CLA work without training and diet? Minimal effects have been observed without an active lifestyle, but results are much better with moderate calorie deficit and regular training. CLA is a supplement, not a replacement for healthy habits.

Is CLA the same as omega-3? No, these are different fatty acids. CLA is conjugated linoleic acid (omega-6 family), while omega-3 is a completely different fatty acid (EPA and DHA). Both are beneficial but in different ways.

Is CLA suitable for vegans? Natural CLA comes from animal sources, but supplemental CLA is often derived from sunflower oil through chemical conversion and is vegan-friendly. Always check the label.

Is CLA safe during pregnancy? CLA safety during pregnancy has not been sufficiently studied. As a precaution, CLA use is not recommended during pregnancy and breastfeeding without medical advice.

See also:

• CLA: A Complete Guide to Fat Loss and Body Composition
• Weight Loss Supplements: What Actually Works?
• Thermogenic Fat Burners: How Thermogenesis Helps You Burn Extra Calories

Read more: Fat Burners: A Science-Based Guide