CLA for Weight Control

Where is it found?

CLA is found mainly in dairy products and also in beef and poultry, eggs, and corn oil. Bacteria that live in the intestine of humans can produce CLA from linoleic acid, but supplementation of a rich source of linoleic acid did not produce increases in blood levels of CLA in one human study.¹ CLA is available as a supplement.

What do the advocates say?*

Research suggests that conjugated linoleic acid (CLA) may help to reduce body fat and increase muscle. The research supporting CLA’s ability to help reduce body fat is good, but more is needed. There are at least seven human studies (two are double-blind and the others are controlled) showing significant reduction of abdominal obesity and body fat mass in overweight and moderately obese people. However, since most of the studies involved a small number of participants and were short in duration, larger double-blind studies are needed to further document the benefits and mechanisms of action.

Although CLA promotes weight loss, which is good for heart health, it is important to moniter cholesterol levels as it may reduce HDL (“good”) cholesterol.

How much is usually taken by dieters?

A double-blind trial found that exercising individuals taking 1,800 mg per day of CLA lost more body fat after 12 weeks than a similar group taking a placebo.² However, two other studies found that amounts of CLA from 0.7 to 3.0 grams per day did not affect body composition.³ ⁴ Most double-blind trials have found that larger amounts of CLA, 3.4 to 4.2 grams per day, does reduce body fat;⁵ ⁶ ⁷ however, one double-blind study of experienced strength-training athletes reported no effect of 6 grams per day of CLA on body fat, muscle mass, or strength improvement.⁸

Are there any side effects or interactions?

Overweight volunteers who took 4.5 grams of CLA per day for one year had an increase in their blood levels of lipoprotein(a), a risk factor for heart disease.⁹ While the significance of this change is not certain, it is possible that long-term use of CLA could increase the risk of developing heart disease.

In a double-blind study of people with type 2 diabetes, supplementing with 3 grams of CLA per day for eight weeks significantly increased blood glucose levels by 6.3% and decreased insulin sensitivity.¹⁰ A reduction in insulin sensitivity was also seen in a study of overweight men without diabetes after treatment with 3 grams of CLA per day for three months,¹¹ although in a study of young sedentary men, 4 grams of CLA per day for eight weeks improved insulin sensitivity.¹² Thus, although the studies are conflicting, CLA may be harmful for some people who have, or are at risk of developing, diabetes. One unpublished human trial reported isolated cases of gastrointestinal upset.¹³

At the time of writing, there were no well-known drug interactions with conjugated linoleic acid.

*Dieters and weight-management advocates may claim benefits for CLA based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on CLA. For more complete and detailed information, including references and safety information, see CLA as a nutritional supplement.

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What is it?

Where is it found?

Why do dieters use it?*

What do the advocates say?*

How much is usually taken by dieters?

Are there any side effects or interactions?

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