Do Diet Pills Really Work?

Many over-the-counter diet pill manufacturers say their product will help you see miraculous weight loss -- like losing up to 30 pounds in 30 days -- without diet or exercise. Their claims sound too good to be true, and most of them are.

Photo courtesy Zantrex-3 promises "546% More Weight Loss."

A few pills, especially the newer prescription varieties (such as Meridia and Xenical), have been shown in clinical studies to help dieters shed a few pounds. But the majority of the ads you see on the Internet and TV are for products that are unregulated, untested and unproven.

Even the most effective diet pills are only meant to be taken for a short period of time -- usually six months or less. During that time, doctor-prescribed weight-loss drugs can trim anywhere from 5 to 22 pounds, or up to 10 percent of your body weight. But after six months, your body develops a tolerance to these drugs' effects, and weight loss plateaus. After that, if you don't also follow a healthy eating and exercise plan, the weight will come right back.

Side Effects of Diet-pill Use

Photo courtesy Amazon.com "All natural" dietary supplements often contain synephrine, an ephedra-like compound derived from certain citrus fruits.

Different diet pills contain different ingredients, so their effects vary:

As fat blockers like orlistat (Xenical) remove excess fats via the intestines, they may cause uncomfortable cramping, gas and diarrhea. Because these drugs also reduce the body's absorption of essential vitamins and nutrients, people who take Xenical are advised to take a daily multivitamin supplement.

Sibutramine (Meridia) and other similar appetite suppressants stimulate the sympathetic nervous system, which can raise blood pressure and heart rate. This increases the risk of heart attack and cardiac arrest, especially among people who already suffer from high blood pressure, irregular heartbeat or heart disease. In fact, between February 1998 and March 2003, the FDA received reports of 49 deaths related to sibutramine. Other, more minor side effects include constipation, headache, dry mouth and insomnia (because the chemicals in these drugs also influence sleep patterns).

Herbal diet pills, even though they're "all natural," can have potentially dangerous side effects depending upon their ingredients. "Herbal" doesn't necessarily mean "safe." Also, because they are considered part of the food industry and are therefore regulated differently by the FDA, there is no guarantee that they can live up to their manufacturers' claims.

Dangerous Diet Pills In the mid-'90s, the diet pill industry was booming. In 1996, more than 18 million dieters in the United States were taking a cocktail of the appetite suppressants fenfluramine (or dexfenfluramine) and phentermine, nicknamed fen-phen -- many with great success. But suddenly, doctors around the country were seeing previously healthy patients who were taking fen-phen developing a potentially fatal heart disease. In September 1997, the FDA announced that it was withdrawing the "fen" drugs from the market because of their link to heart problems. Phentermine is still available on its own. Another popular diet pill ingredient in the '90s was a powerful amphetamine-like stimulant called ephedra (or the Chinese herb ma huang), which, in combination with caffeine, triggered measurable weight loss. The problem was, because it sped the heart rate, ephedra also dramatically increased the risk of heart attack and stroke. Ephedra is related to epinephrine (adrenaline), which, during times of stress, constricts blood vessels, elevates heart rate and gets the body ready to fight or flee. At least 155 people died from taking medications containing ephedra. In late 2003, the FDA announced that it would ban the sale of all ephedra-containing drugs. In response, manufacturers of over-the-counter diet pills such as Dexatrim, Metabolife and AcuTrim began removing the ingredient from their products and now produce ephedra-free versions.

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