What it is
Pyruvate forms in the body when carbohydrates and protein convert into energy. Several foods, including red apples, cheese, dark beer, and red wine, contain small amounts of pyruvate. Pyruvate provides energy to the body and is also an antioxidant. It enhances weight loss efforts and may improve exercise endurance.

How it works
Pyruvate appears to work as a weight loss aid by cranking up the resting metabolic rate, which is the minimum number of calories the body burns just to support the basics of breathing, circulating blood, and other organ functions. The higher your resting metabolic rate, the more calories you use, even when lying on a couch or sitting at a desk. Pyruvate's role in weight loss is well documented in clinical trials (Journal of the American Pharmaceutical Association, 2004, vol. 44, no. 1).

A university research group in Pittsburgh conducted several clinical studies using pyruvate for weight reduction. One study analyzed the amount lost by 34 overweight men and women on a low-fat diet (less than 24 percent of calories from fat) while taking 22 to 44 grams daily of either pyruvate or a placebo (American Journal of Clinical Nutrition, 1994, vol. 59, no. 2). After six weeks, those supplementing their low-fat diets with pyruvate showed significantly greater weight loss and a decrease in body fat, compared with those on the low-fat diet alone.

The large amount of pyruvate used in this study can be hard on the stomach, not to mention the pocketbook. Fortunately, more recent research indicates that much lower doses can do the job just as well. In another six-week study, 26 overweight individuals combined either 6 grams of pyruvate supplement or a placebo with a daily exercise program (Nutrition, 1999, vol. 15, no. 5). Once again, the pyruvate group lost more weight and more fat mass than the placebo group.

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And there's more good news for dieters. Pyruvate supplements appear to stave off the dreaded yo-yo effect, in which pounds lost during a diet seem to come back with a vengeance. In another study from the Pittsburgh group, researchers tracked the weight fluctuations of 17 obese women (International Journal of Obesity and Related Metabolic Disorders, 1996, vol. 20, no. 10). For the first three weeks, the women lost weight with a low-calorie diet. Over the next three weeks their calorie intake was upped considerably, mimicking the seesaw pattern common among many dieters. When eating more, women who took pyruvate (compared with those taking a placebo) regained less weight and less body fat.

In addition, several clinical trials show that supplementing with pyruvate may improve exercise endurance, possibly by getting more glucose into muscle cells to keep those muscles working. Interestingly, some research indicates that when people take pyruvate and then work out, exertion feels less intense. Thus, they are able to work harder before feeling fatigued (Medicine and Science in Sports & Exercise, 1998, vol. 30, no. 6).

Side effects
In common doses (5 to 6 grams daily), pyruvate doesn't cause trouble for most people. However, larger amounts (10 grams per day and more) can trigger stomach upset, bloating, gas, and diarrhea.

How to take it
Pyruvate-rich foods are a great source of this compound; for example, a red apple contains nearly half a gram of pyruvate. The average American diet naturally contains about this amount daily. For weight loss and athletic purposes, take 5 to 6 grams of pyruvate daily. Powdered forms of pyruvate supply 3 grams per teaspoon. Tablets and capsules come in 500, 750, or 1,000 mg doses.

Pyruvate's cost varies widely. For the most economical price (as little as $20 per month), buy larger bottles, such as 200 capsules, each containing 500 to 1,000 mg.

Victoria Dolby Toews, MPH, is an Oregon-based health writer and author of User's Guide to Sexual Satisfaction (Basic Health, 2003).