CLA, or conjugated linoleic acid, is an isomer of linoleic acid, meaning it has a small rearrangement of it's molecular structure resulting in a change of the functions of the nutrient. It is a naturally occurring free fatty acid found in small amounts in meat and dairy products, it is not produced by the body so it must be supplied by the diet. CLA was first identified in 1978 by Dr. Michael Pariza as he was studying beef extracts at the University of Wisconsin-Madison. Tonalin CLA ( a trade marked version) is the leading brand of CLA supplements and is derived from safflower oil, which is a good source of linoleic acid. This is the # 1 selling version in the world and the version with the most research behind it.
- Changes body composition by reducing body fat and preserving lean muscle mass.
It does this by the following four ways:
- Decreases the amount of fat stored after eating
- Increases how fast fat is broken down in fat cells
- Increases the rate of fat metabolism
- Decreases the total number of fat cells in our bodies
This is the primary reason people buy CLA – it is, in fact, one of the top fat loss products on the market and offers an alternative to those who want a fat burner without a lot of caffeine. It does not work in the same way as a caffeine based fat burner, of course, so many people will use CLA as part of a fat loss “stack” to promote faster results.
More than 600 CLA studies have been published over the last 25 years – it would be impractical to attempt to list them all so I will list a small sampling of these studies below.
"Conjugated Linoleic Acid Reduces Body Fat in Healthy Exercising Humans"
Institution: Journal of International Medical Research
Description: Volunteers received CLA or placebo for 3 months, and were asked not to make any changes in their diet and lifestyle during the study.
Results: The CLA group had a significant reduction in body fat percent from 21.3% to 17.0%, and a reduction in body weight (from 69.6 to 68.9 kg).
"Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial."
Institution: International Journal of Obesity
Description: Volunteers received CLA or placebo for 4 weeks, and did not make changes in their diet and lifestyle during the study.
Results: The CLA group had a significant decrease in abdominal diameter, an average of one inch from their waistlines.
“Conjugated Linoleic Acid supplementation for One Year Reduces Body fat Mass in Healthy Overweight Humans”
Institution: American Society of Clinical Nutrition
Description: Overweight volunteers received CLA each day over 1 year or received a placebo (control group) per day.
Results: Mean body fat mass in the CLA groups was 6.9% – 8.7% lower than that in the placebo-control group. Long-term supplementation with CLA reduced body fat mass in healthy overweight adults.
"Supplementation with Conjugated Linoleic Acid for 24 Months Is Well Tolerated by and Reduces Body Fat Mass in Healthy, Overweight Humans"
Institution: Journal of Nutrition
Description: Follow-up of 12 month placebo-controlled study. Moderately overweight volunteers received CLA each day.
Results: Subjects who lost body fat mass in year one of the study could keep their body fat off, and subjects who previously had received placebo and were switched to CLA, now lost body fat mass significantly. Leptin levels decreased over the whole period of supplementation by more than 20%. Long-term supplementation with CLA is safe over 24 months at least.
"The Effects of Conjugated Linoleic Acid Supplementation during Resistance Training"
Institution: American College of Sports Medicine (2006)
Description: Healthy men and women received CLA or placebo while participating in a total-body resistance-training program for a 7-week period. Measurements, before and shortly after completion of the study, included total body weight, percent body fat, lean body mass, fat mass and muscle thickness.
Results: After 7 weeks, the CLA group had greater increases in lean tissue mass and greater losses of fat mass and percent fat compared with the placebo group. Additionally, the resting metabolic rate (RMR) remained constant in the CLA group, while RMR decreased in the placebo group.
"The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain"
Institution: International Journal of Obesity (2006)
Description: Forty healthy, overweight men and women between the ages of 18-44 years with a body mass index between 25-30 kg/m2 received CLA or placebo during a 6 month period. Body weight was measured monthly during the pre-holiday season (August-December), holiday season (November-December) and post-holiday season (January-March).
Results: Compared to CLA, the placebo group showed a greater rate of weight gain during the holiday season. Within the placebo group, holiday weight change was significantly greater compared to the pre-holiday period. Six-month change in body composition was improved with CLA compared to placebo, and body fat was significantly reduced within the CLA group.
CLA first appeared as a supplement in the 90's but did not sell all that well, these studies represent the current thinking about CLA and help explain why it's currently popular.
CLA comes as a stand-alone product as well as part of formula products. Even though the Tonalin brand is the most popular, not all CLA products come from that manufacturer. Clarinol is another trademarked version of CLA – this particular product, however, does not list the “natural source” of it's version. Other products are simply “CLA from safflower oil”. In some cases, the source is not even listed on the label. So when making your buying decision, label reading is a must and buying a trademarked version highly suggested. I would also suggest doing some research on the two trademarked versions to better help you make the right choice. Of the formula products, CLA is typically part of a “healthy fat” complex intended to help burn fat. There is a whole category of products out there that are based on this idea and of course, there is a little bit of controversy as to how well they work. It's also in some of those very same caffeine based fat burners that many people buy CLA to avoid.
CLA comes primarily as a soft gel capsule and will come in a powder version in many of the formula products. Typical dosage is 1-2 up to 3 times a day and it does come in strengths ranging from 1000mg to 1300mg per soft gel. As usual, careful label reading is recommended and adherence to the instructions suggested.