Can you pop a pill, sit on the couch, grab a doughnut, and hope to lose weight? Those late night infomercials make it sound like you can -- if you're willing to fork over the cash for a "fat burner" or "fat trapper." But experts say, "Fat chance."

By Alison Palkhivala

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.