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L-Carnitine May Not Promote Weight Loss

L-Carnitine May Not Promote Weight Loss

CHICAGO--In the June issue of Sport Nutrition & Exercise Metabolism, it was found that L-carnitine supplementation combined with aerobic exercise may not promote weight loss. For eight weeks, 36 moderately overweight, pre-menopausal women were given either a placebo or 2 g of L-carnitine twice a day. All subjects walked 30 minutes a day, four days a week. Body composition and resting energy expenditure (REE) were measured; no significant changes were noted in body mass, but REE increased in both the L-carnitine and placebo groups. Five of the L-carnitine group did not finish the study after experiencing nausea and diarrhea.

According to Paula Gaynor, Ph.D., manager of scientific affairs at Lonzagroup (a supplier of L-carnitine), this study had numerous flaws. No calorie restrictions were stipulated for either group, and the exercise program was moderate and had little or no supervision. Gaynor noted that 4 g a day of L-carnitine may have been too large a dose for some people [thus, the diarrhea], especially if they already had high levels of naturally-occurring L-carnitine in their blood. Overall, Gaynor concluded, "I would not call it a well-controlled or even a well-designed study." For an abstract of the study, visit

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