A reader posts the following comment to the Shape Up Board:

"I just wanted to respond to the article bashing weight loss drugs. I took Metabolife and I lost 20 pounds. That was six months ago and I haven't gained any back, no heart problems. My sister takes it now and she lost 10 pounds so far. We didn't have to exercise. I just wanted to say that they do work and if you follow the directions they don't hurt you."

Her comment deserves a fair response, one that isn't unduly argumentative and alarmist yet presents the more complete picture.

The ingredient in Metabolife that has generated the controversy is ephedra. Ephedra, also known as ma huang, has a long history of being used in China for upper-respiratory disorders, and synthetic versions are found in hundreds of over-the-counter medications, mainly for allergies and asthma. Its primary active ingredients are stimulants -- ephedrine and pseudoephedrine. These mimic the "fight or flight" response in which the body secretes adrenaline.

In addition, it can suppress appetite and may help speed up metabolism.

Is it Satan Incarnate? No, obviously not. But my problem with recommending it across the board stems from its potential side effects -- by acting like adrenaline; it speeds up the heart rate and can also have a diuretic effect. Couple it with the coffee most people drink, and the potential for mischief increases. It interacts with numerous medications and can easily cause nervousness, heart palpitations and insomnia. Developing a tolerance for it is not uncommon, and in severe cases with susceptible individuals it can cause dangerously high blood pressure.