Oct. 15, 2001 -- Anyone who has watched TV after midnight has heard the claims. Eat all you want, never exercise , and still lose weight with this little pill.

Unfortunately, scientific research has not borne out such claims. These products are categorized as dietary supplements , not as drugs. According to current FDA regulations, that means nobody has to prove that they work.

"The number and quality of good, randomized, double-blind [studies] that really explore the question of efficacy are very limited for these herbal products and dietary supplements ," Steven Heymsfield, MD, tells WebMD. "That's virtually true for the entire category of [weight loss] products."

Heymsfield is a professor of medicine at Columbia University and deputy director of the New York Obesity Research Center at St. Luke's-Roosevelt in New York. He says there's no scientific proof the pills work -- but what's the word on the street?

Personal trainer Todd Person, owner of Metabolic Project, a personal training facility in Los Angeles, says that when used in combination with diet and exercise, they do help speed people along to their fitness goals.

Matthew Martin, 31, of Chicago, Ill. was in poor condition when he decided to begin training for a triathlon. After a little research on the Internet, he picked the fat burners that he believed might work for him. He took them for about three months and did find them helpful.

"I didn't do a test ... I just used them, and they seemed to help me not want to eat as much," he says."

Fat Trappers

Fat-trapping products generally contain chitosan. It comes from the powdered shells of shrimps, crabs, and other shellfish. Supposedly it binds to fat in the food you eat, keeping it from being digested. While there is evidence that it does help prevent you from absorbing dietary fat, its effects may be too small for you to actually notice anything. A few small studies have shown that people on calorie-restricted diets lose slightly more weight if they're taking chitosan.

Jana Klauer, MD, is a research fellow also at the New York Obesity Research Center. She says that chitosan is simply a source of fiber. While a high fiber diet is good for weight loss, there are lots of cheaper alternatives.

The danger of chitosan is that it may get in the way of your body's ability to absorb fat-soluble nutrients. These include vitamin A, vitamin D, and the disease-fighting phytochemicals found in many fruits and vegetables. No matter what the manufacturers claim, it's probably not a good idea to take this product for more than about three months at a time.

Fat Burners

Fat burners are generally some combination of herb-derived stimulants, essential fatty acids, chromium picolinate, pyruvate, and/or hydroxycitric acid.

Herb-derived stimulants include caffeine and ephedrine as well as the herbs guarana and ma huang. Two or three of these stimulants are usually 'stacked' together in one weight loss product, often along with aspirin or willow bark. They are supposed to increase energy while stimulating fat burning. Most experts agree they do work when combined with exercise. Their safety, however, is another matter.

"Ephedra [which comes from ma huang] is effective ... particularly when combined with aspirin and other ingredients," says Heymsfield. "But it raises blood pressure and can cause fatal heart attacks, [heart] arrhythmias, and strokes. ... The ads are very deceptive for ma huang regarding safety."

Klauer and colleagues studied the weight loss potential of ephedra last year. "People did lose more weight with it," she says, "but their elevations in blood pressure remained high even after they stopped the drug. ... So, I really don't recommend ephedra."

According to Klauer, both ephedra and caffeine work by increasing your resting metabolic rate, which can be done more safely and cheaply simply by exercising more and eating less.

Despite a family history of heart disease, would-be triathlete Matthew Martin chose a combination of caffeine and ephedrine as his fat-burning program. He did notice his heart rate speed up after he popped a pill, but it didn't bother him. He found that taking the pills boosted his energy enough to make him want to work out more and reach his fitness goals sooner. One month after stopping the program, he remains in good shape, but he's also still in full-blown triathlon training.

Essential fatty acids include conjugated linoleic acid (CLA) and flax seed oil. They are sometimes used in combination with garlic to increase muscle mass and burn fat. They seem to be helpful in animals, and some new research is showing promise in humans.

Michael W. Pariza, PhD, director of the Food Research Institute at the University of Wisconsin in Madison, has studied CLA. "The clinical evidence is certainly emerging that it can be helpful, particularly in controlling fat and weight gain," he tells WebMD. "We also have pretty good evidence that it relieves a lot of the adverse effects [such as dizziness and stomach problems] that people have when they are dieting."

A new study on CLA came out in the August 2001 issue of the International Journal of Obesity. In it, a Swedish group of experts showed that overweight men taking CLA lost more fat than those not taking the product.

However, Pariza warns that not all CLA supplements are of high quality. He recommends that consumers look for supplements containing one of two branded types of CLA, called Conalin and Clarinol.

Chromium picolinate and pyruvate were very popular a few years ago. Neither has held up well to scientific scrutiny. "There was a chromium study that showed it really had no effect on weight loss whatsoever," says Klauer.

Hydroxycitric acid (HCA) is a form of citric acid. It comes from a fruit -- the Malabar tamarind -- that grows in Southeast Asia.

Debasis Bagchi, PhD, CNS, is an adjunct professor of toxicology at Creighton University School of Pharmacy in Omaha, Neb. He's also vice president of research and development at InterHealth Nutraceuticals, which makes an HCA-containing fat burner called CitriMax. Bagchi says HCA stimulates the breakdown of fat, although studies of this product have had conflicting and not very encouraging results. He and Person also say it helps suppress appetite.

Heymsfield and colleagues looked at HCA in a study funded by a commercial manufacturer. Using the commercially sold HCA products, they could not find any effect of the product. HCA manufacturers said the researchers had not used the proper forms of HCA, but Heymsfield remains unconvinced.

The Bottom Line

Fat trappers and fat burners are expensive. Most regimens cost from about $50 to several hundred dollars each month. What you get in return may not be worth the cash. While there is some scant evidence that a few of these products have a minor effect, none are the magic bullet that will allow you to lose weight while you munch chips in front of the TV.

Even the experts who like these products agree that they have to be combined with proper diet and regular exercise to work. If you've got the willpower to stay on a diet and exercise routine and have some extra cash to blow, by all means, see if one of the safer of these products will speed up your efforts to get in shape. If you're not going to stick to a diet and exercise routine, you may be better off spending your money elsewhere.

"It all basically comes down to eating a balanced, low fat diet high in complex carbohydrates and getting aerobic exercise daily," says Klauer.

What a surprise.