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Supplements will shrink
your wallet, not youWeight loss is a national obsession, clearly verified by the hundreds of dietary supplements that claim to help achieve the perfect body.
Sorting out the facts from the hype isn't always easy. Some supplements have been shown to promote weight loss in laboratory settings, but these conditions do not always reflect the real world. Today we will address three of the more common ingredients found in these products.
Question: What is pyruvate and does it really promote weight loss?
Answer: This chemical is formed in the body, primarily from the breakdown of the sugar glucose. It is also found in small amounts in some foods.
In the early '90s, researchers from the University of Pittsburgh reported that supplemental intake of pyruvate helped promote fat loss and inhibit muscle loss. Since then, the substance has been marketed widely as a dietary supplement.
The human studies did show enhanced fat loss, but that is not what is typically seen in the real world. One reason is that the pyruvate dose used in the studies was about 20 to 40 grams per person per day. This is significantly greater than the 5 or 6 grams of pyruvate recommended per day in dietary supplement form. A likely reason for the lower dose is that pyruvate is fairly expensive and few individuals would be willing to pay so much.
Q: Why is hydroxycitric acid from Garcinia cambogia added to weight-loss supplements?
A: Hydroxycitric acid is extracted from the fruit rind of the Garcinia cambogia plant and related species. The compound inhibits an enzyme that is involved in one step of the conversion of carbohydrate to fat in the body. Studies involving rats indicated that the substance can be quite effective in decreasing the accumulation of body fat.
But unlike rats, people do not typically convert much carbohydrate to fat. Humans generally use carbohydrate directly for energy and store fat as fat. Consequently, well-controlled human studies report little or no benefit from hydroxycitric acid when it comes to fat loss.
Q: What is conjugated linoleic acid and how does it promote fat loss?
A: The abbreviation CLA refers to a group of polyunsaturated fatty acids found in animal fats from sources such as milk, beef and lamb. Research has shown that CLA may help to reduce the risk of heart disease and colon cancer. Some of these studies on humans have shown that these polyunsaturated fatty acids also may help promote fat loss.
How CLA works is unclear. In the studies that observed a loss of body fat, participants were taking 4 to 6 grams per day; no effect was seen using 3 grams per day.
Also, recent studies in pregnant rats consuming a diet high in CLA found that their offspring had some anatomical abnormalities. Thus, long-term safety is unknown.
Pyruvate, hydroxycitric acid and CLA do seem to be relatively safe when compared to weight-loss supplements that contain herbal stimulants, such as ma huang. However, adding regular physical activity to your lifestyle (about a half an hour to an hour per day) has more scientific support than anything in a bottle.
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Alan Titchenal, Ph.D., C.N.S., is a sports nutritionist in the
Department of Human Nutrition, Food and Animal Science,
University of Hawaii-Manoa.Joannie Dobbs, Ph.D., C.N.S., is a food and nutrition consultant
and owner of Exploring New Concepts, a nutritional consulting firm.
She is also responsible for the nutritional analyses
indicated by an asterisk in this section.