CLA (conjugated linoleic acid) is a
free fatty acid that may prove to
be essential to our diet. Studies
show that CLA can play a vital role
in reducing body fat and improving muscle tone. In the
past, it was readily available in beef and dairy products,
but today, it is no longer present in great quantities. To
obtain about 1000 mg of CLA in food you would have to
consume three pounds of hamburger, twenty-five slices
of American cheese or half a gallon of ice cream. Of
course, the adverse effects of eating these high saturated
fat foods might eclipse the benefits obtained from the
CLA. Consequently, the use of a CLA supplement is a
sensible alternative and may even help you reduce body
fat. Researchers think that CLA helps reduce body fat
deposits by promoting apoptosis (programmed cell
death) in fat cells.1
In two different double-blind, 12-week studies, CLA
supplementation has been shown to promote a decrease in
body fat. In one study,2 53 men and women supplemented
with 4200 mg CLA daily or a placebo. Body fat decreased a
significant 3.8 percent in the CLA-treated group, compared to
placebo. In the other study,3 47 overweight or obese subjects
received varying amounts of CLA daily (1700 mg to 6800 mg)
or a placebo. Results showed significantly higher reduction in
body fat mass in those receiving 3400 mg and 6800 mg CLA
compared with the placebo group.
In an eight-week, double-blind study,4 22 volunteers
received 700 mg of CLA for four weeks and 1400 mg of CLA for
the next four weeks, or a placebo. Diet was controlled and there
were no significant differences in calories or macronutrient
intake (carbohydrate, fat, protein) between the two groups.
The results were that body fat and fat mass was significantly
reduced in the CLA group with 1400 mg, but not with 700 mg
Other research5 suggests that consuming 1800 mg or
3600 mg CLA daily also reduces hunger and improves satiety
and feeling of fullness, compared to placebo.
The previously cited studies were of relatively short length
(maximum 12 weeks). So what happens when CLA is
supplemented for a longer period of time? To determine the
effect of CLA supplementation over a one-year period, 180
overweight or obese men and women received 4500 mg CLA
daily or placebo while consuming a diet without any calorie
restrictions in a double-blind study.6 The results demonstrated
a statistically significant reduction in body fat mass in the CLA
group compared to placebo, and a statistically significant
increase in lean body mass (i.e., muscle) compared to placebo.
These changes were not associated with diet or exercise.
Likewise, during a 24-month research period,7 134
overweight volunteers received 3400 mg of CLA or placebo
daily in a double-blind study for 12 months, and then continued
for another 12 months in an open study with the goal of
assessing CLA safety and other effects. The results of these
studies showed that CLA supplementation for 24 months in
overweight adults was well tolerated, and also confirmed that
CLA decreases body fat mass, and may help maintain initial
reductions in body fat mass and weight in the long term.
Although long-term research indicates that CLA is generally well
tolerated, some individuals may experience gastrointestinal
upset including diarrhea, nausea, loose stools, and dyspepsia.
One study8 suggests that CLA may increase insulin
resistance and blood sugar levels in diabetics; so individuals with diabetes who take CLA should closely monitor their
blood sugar levels. The same study suggests that men with
abdominal obesity and metabolic syndrome may be more
likely to develop hyperproinsulinemia and insulin resistance
when supplementing with CLA.
Both short-term and long-term research suggests that
supplementation with CLA by overweight and obese
individuals are associated with a reduction in body fat.
For those wishing to try CLA, I recommend a supplement
providing 1200 mg CLA per softgel capsule. At this dosage
level you can emulate the amounts given in research by
consuming 3 or 4 softgels daily, divided between breakfast,
lunch and dinner.
- Miner JL, Cederberg CA, Nielsen MK, et al. Conjugated linoleic acid (CLA), body fat, and apoptosis. Obes Res 2001;9:129–34.
- Smedman A, Vessby B. Conjugated linoleic acid supplementation in humans--metabolic effects. Lipids 2001;36:773–81.
- Blankson H, Stakkestad JA, Fagertun H, et al. Conjugated linoleic acid reduces body fat mass in overweight and obese humans. J Nutr 2000;130:2943–8.
- Mougios V, Matsakas A, Petridou A, et al. Effect of supplementation with conjugated linoleic acid on human serum lipids and body fat. J Nutr Biochem 2001;12:585–94.
- Kamphuis MM, Lejeune MP, Saris WH, Westerterp-Plantenga MS. Effect of conjugated linoleic acid supplementation after weight loss on appetite and food intake in overweight subjects. Eur J Clin Nutr 2003;57:1268-74.
- Gaullier JM, Halse J, Hoye K, et al. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr 2004;79:1118-25.
- Gaullier JM, Halse J, Høye K, Kristiansen K, Fagertun H, Vik H, Gudmundsen O. 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(4):778-84.
- Riserus U, Arner P, Brismar K, Vessby B. Treatment with dietary trans10cis12 conjugated linoleic acid causes isomerspecific insulin resistance in obese men with the metabolic syndrome. Diabetes Care 2002;25:1516-21.