Metabolift, a supplement made by TwinLab, promises to increases your energy levels while helping you lose weight. The company does, however, hedge its bets by also suggesting that people taking the supplement follow a low-fat diet and exercise program. Metabolift contains a number of herbs that can cause serious side effects if taken in excess. Discuss taking this supplement with your medical practitioner before starting, particularly if you have any health issues.
Guarana Seed Extract
Gauarana, a bush grown in the Amazon, has berries used for medicinal purposes. The plant contains a large amount of caffeine, which increases metabolism; the dose listed for this supplement is 800 mg, 22 percent caffeine. Side effects of guarana include increased heart rate or blood pressure, palpitations or irregular heartbeat, anxiety of restlessness. In a 2001 study on another supplement containing guarana, guarana delayed stomach emptying, resulting in a feeling of fullness which led to decreased calorie intake and weight loss over a 45-day period, Ray Sahelian, M.D., reports on his website.
Citrus Aurantium Fruit Extract
Citrus aurantium, the second ingredient listed on the nutritional label, contains synephrine, which is chemically similar to epinephrine, a drug which increases heart rate and can raise temperature, blood pressure and heart rate. This supplement is often used as a substitute for ephreda, banned from American over-the-counter supplements, according to an October 2006 report published by the Food and Drug Administration in the "Annals of Pharmacology." Metabolift contains 325 mg of citrus aurantium fruit extract.
St. John's Wort
The third ingredient listed in Metabolift is a "proprietary and thermogenic metabolic blend" whose first ingredient is St. John's wort, an herb often used as an over-the-counter sedative and to treat depression, anxiety and sleep disorders. St. John's wort does not increase weight loss but may offset some of the symptoms from other ingredients.
L-Phenylalanine
L-phenylalanine, an essential amino acid obtained mostly from dietary protein, is the second ingredient in the "proprietary blend." L-phenyalanine has no benefit as a weight-loss supplement but may have some benefit for use in depression, although this has not been well proven, the University of Maryland Medical Center states. L-Phenylalanine can cause anxiety and jitteriness in children.
Green Tea Leaf Extract
Green tea leaf extract, another ingredient in the proprietary blend, may have some benefit as a weight-loss supplement, Dr. Sahelian reports.
References
- Twinlab: Metabolift
- Dr. Ray Sahelian,M.D.: Guara Seed Extract Side Effects
- PubMed:Citrus Aurantium, an Ingredient of Dietary Supplements Marketed for Weight Loss: Current Status of Clinical and Basic Research
- National Center for Complementary and Alternative Medicine: St. John's Wort
- University of Maryland Medical Center: L-Phenylalanine
- PubMed: Consumption of Dietary Supplements Containing Citrus Aurantium (Bitter Orange)--2004 California Behavioral Risk Factor Surveillance Survey; Center for Food Safety and Applied Nutrition; K.C. Klontz
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