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CLA Reduces Body Fat up to 9% and Helps Keep It Off

A two-year study just published in the April 2005 issue of the prestigious Journal of Nutrition concludes that long-term supplementation with conjugated linoleic acid (CLA) is safe and well-tolerated. Furthermore, it confirms that taking CLA decreases body fat mass (BFM) and maintains lean body mass (LBM), and so also aids weight management, reducing the potential ‘yo yo’ effect often associated with diet plans.

“This study is particularly exciting because it was intended to confirm the safety of Tonalin® CLA, but it went an important step further demonstrating that the people taking CLA also maintained their lean body mass and didn’t regain the body fat they’d lost,” said Nina Likins, Tonalin® CLA Marketing Manager. “It’s hard enough top lose body fat and even more difficult to keep it off, so this new research will be welcome news to dieters and those that formulate clinically proven products for this population,” she explained.

Overweight subjects who took 3.4 grams of CLA per day lost body fat in the first 12 months of the study, and were able to avoid regaining that fat in the second 12 months. The results of the study corroborate and expand upon earlier findings, published last spring in the American Journal of Clinical Nutrition, which revealed that CLA reduced body fat mass in overweight, but otherwise healthy, adults by as much as 9 percent. They also reveal that people with the highest body mass index (BMI) and body fat mass (BFM), especially women were more likely to lose body fat than those with lower BFM.

Weight management is key, as research has shown that almost all dieters regain the weight they have lost within five years. This study shows that healthy, overweight participants taking a conjugated linoleic acid supplement for two years lost body fat and did not regain it. “CLA helped study participants keep off lost weight while maintaining lean body mass – which keeps the metabolism going strong and burning calories, thereby reducing the chances of weight regain,” said Dr. Jean-Michel Gaullier of Scandinavian Clinical Research in Kjeller, Norway, and project manager of the CLA study.

“Having a product that reduces the health risks of going on and off diets - the ‘yo-yo’ effect - is groundbreaking. Interest in CLA has been spurred by consumers’ increased demand for safe, stimulant-free products for reducing unwanted inches,” said Dr. Michael W. Pariza, director of the Food Research Institute (University of Wisconsin-Madison) and a renowned CLA expert.

Another important finding is that CLA supplementation helps lower levels of leptin. High levels of the hormone leptin are associated with increased body weight. Over the course of 24 months, leptin levels dropped 20-35 percent as study subjects lost body fat.

This is the first study to document the long-term safety and efficacy of CLA supplementation over a two-year period without lifestyle or dietary restrictions. It began as a randomized, double-blind, placebo-controlled study over a 12-month period, but was later extended by a further 12 months as open treatment. Of the 157 subjects that completed the original study, 134 volunteered to participate in the extension, and 125 completed the entire 24-month study. The second 12 months were aimed at evaluating the safety of CLA and assessing its effects on body composition (body fat mass, lean body mass, bone mineral mass, body weight and BMI) over a prolonged period of time.

Overall, CLA supplementation for 24 months in healthy, overweight adults was well tolerated. Most of the adverse effects reported during the double-blind phase were unrelated to the use of CLA (94 percent). The remainder (6 percent) were rated “mild” reactions, with the most frequent complaints being gastrointestinal in nature, evenly distributed over all groups including the placebo group.

The CLA used in this study was Tonalin® CLA, an exclusively licensed product of the Cognis Group. CLA, a polyunsaturated fatty acid, found naturally in ruminant animals like cows, lowers the amount of fat normally stored after meals, helping the body to break down and efficiently use fat. However the changes during the past 30 years in how cattle are raised (grain fed vs. grass fed) coupled with the trend toward low-fat dairy and reduced beef consumption have drastically reduced the amount of CLA humans acquire through diet. It is thought that CLA has two main sites of action: the adipocytes or fat cells, the principal site of fat storage, and the skeletal muscle cells, the principal site where fat is burned for energy. It has been proposed that CLA decreases body fat mass through four actions: by decreasing the amount of fat stored after eating, increasing the rate of fat metabolism, increasing the rate of fat breakdown in fat cells, and decreasing the total number of fat cells.

As the latest research shows, CLA’s primary benefit is body fat reduction and helping to prevent fat regain - and as such it could be a valuable addition to a healthy diet and exercise program for weight management.


After 12 mo in a randomized, double-blind, placebo-controlled trial of conjugated linoleic acid (CLA) supplementation (2 groups received CLA as part of a triglyceride or as the free fatty acid, and 1 group received olive oil as placebo), 134 of the 157 participants who concluded the study were included in an open study for another 12 mo.

The goals of the extension study were to evaluate the safety [with clinical chemistry analyses and reported adverse events (AEs)] and assess the effects of CLA on body composition [body fat mass (BFM), lean body mass (LBM), bone mineral mass (BMM)], body weight, and BMI. All subjects were supplemented with 3.4g CLA/d in the triglyceride form.

Circulating lipoprotein(a) and thrombocytes increased in all groups. There was no change in fasting blood glucose. Aspartate amino transferase, but not alanine amino transferase, increased significantly. Plasma total cholesterol and LDL cholesterol were reduced, whereas HDL cholesterol and triglycerides were unchanged. The AE rate decreased compared with the first 12 mo of the study. Body weight and BFM were reduced in the subjects administered the placebo during the initial 12 mo study (–1.6 ± 3.2 and –1.7 ± 2.8 kg, respectively). No fat or body weight changes occurred in the 2 groups given CLA during the initial 12 mo. LBM and BMM were not affected in any of the groups. Changes in body composition were not related to diet and/or training.

In conclusion, this study shows that CLA supplementation for 24 mo in healthy, overweight adults was well tolerated. It confirms also that CLA decreases BFM in overweight humans, and may help maintain initial reductions in BFM and weight in the long term.


Jean-Michel Gaullier, Johan Halse, Kjetil Høye, Knut Kristiansen, Hans Fagertun, Hogne Vik, and Ola Gudmundsen. Supplementation with Conjugated Linoleic Acid for 24 Months Is Well Tolerated by and Reduces Body Fat Mass in Healthy, Overweight Humans
J. Nutr. 2005 135: 778-784.

Key concepts: cla, conjugated linoleic acid, body fat,