Weight loss with pyruvate or chitosan?

Dear Alice,

There seems to be a lot of hype these days about pyruvate and chitosan, in terms of helping with weight loss. Claims have been made that chitosan is essentially a "fat-trapper" (take two before a fatty meal, and none of the fat will stay in your body), and pyruvate is supposed to increase your cells' activity and therefore increase your metabolic rate to help you lose weight without exercising. What is your take on this? Are either of these two "natural" products safe for your body? Has there been any scientific proof that they really work? Will the weight come back after you quit taking the pills?


Dear Curious,

Many weight loss supplements come and go with dizzying regularity. Two that are currently being sold in the marketplace are pyruvate and chitosan (among others). Pyruvate is a substance made in our bodies as a result of glucose metabolism. Promoters of this supplement claim that it helps in losing weight. One lab, led by R. Stanko in Pittsburgh, PA  studied the effects of pyruvate in obese women over the course of three weeks. The subjects were divided into two groups -- both followed a 1,000-calorie liquid diet, but one group took 36 grams of pyruvate per day. The women taking pyruvate lost an average of 13.0 pounds (versus an average of 9.5 pounds for the non-pyruvate group -- a 3.5 pound difference). Here's the catch: pyruvate usually comes in 500 to 1,000 mg capsules. You would have to take anywhere from 36 - 72 capsules a day to match the amount administered in the study. Besides being inconvenient, the cost of these supplements would be around fifteen or twenty dollars every day. In addition, some people taking as little as 30 - 100 grams per day experience diarrhea and some stomach upset. Apparently, pyruvate is not a bargain when it comes to losing an extra three pounds. And, the results of this study may not even apply to you, if you are not an obese woman - others may not experience the same effects seen by the study participants.

Chitosan is made from chitin, which forms the shells of crabs, shrimp, lobsters, etc. It's similar to fiber, in that it passes through the intestinal system unabsorbed. Chitosan also takes a little recently consumed fat along with it for the ride, but it doesn't remove the fat deposits already on your body. Some very small European studies (only one of which was published in a peer-reviewed journal) have been done looking at this substance. It's unclear if chitosan can excrete enough fat to make a difference in weight loss. However, if chitosan binds and excretes fat that's consumed, then it will prevent the absorption of important fat-soluble vitamins (A, D, E, and K) and some valuable phytochemicals, which help to prevent disease. Another important point to consider is that some medications are fat-soluble and their effectiveness may be compromised. Women need to know this because oral contraceptives and estrogen fall into this category.

As with all supplements, these substances aren't regulated by the U.S. Food and Drug Administration (FDA), so purity and safety aren't guaranteed. Even if you were to lose weight on either of these supplements, it would surely return if you revert back to unhealthy habits. There's no magic answer for permanent weight loss, except a reasonable healthful eating and exercise program. Save your money for some healthy food and perhaps a new pair of sneakers!

Last updated Jun 05, 2015
Originally published Oct 08, 1999

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