Diet Pills: Too Good to Be True?

Ads for diet pills are everywhere -- on TV and the radio, in magazines and newspapers, even on the Internet. They entice you with heartfelt testimonials, unbelievable before-and-after pictures and the inevitable money-back guarantees. All you have to do is run out and purchase the latest, hottest, this-one-has-got-to-work weight loss miracle in a bottle!

Not so fast. Get the facts before you fall for these marketing ploys.

There are many reasons to proceed with extreme caution when using diet pills. While it's true that sometimes you may actually lose a little weight with them, the pounds return once you stop taking the product. Most of these weight loss quick fixes include a small-print recommendation that you also adopt a lower-calorie diet and an exercise program -- which is going to help you lose weight anyway. And supplements generally aren't well regulated, so the actual content of the active ingredients in diet pills can vary widely from product to product.

Even more worrisome, all diet pills have potentially dangerous side effects. Everyone knows that people who take prescription medications need to check with their physicians before using any type of weight loss supplement. But even healthy people who aren't taking any other meds have experienced negative health effects from diet pills. The bottom line: Always check with your physician before you take anything that promises to "melt off the weight."

If you're still thinking about taking a diet pill, read the label for the active ingredients and check out whether there's any basis to their claims -- and whether they're potentially dangerous.

Find out the real deal on metabolism boosters, fat burners, carbohydrate blockers, fat blockers and more.

METABOLISM BOOSTERS
Ephedra
The FDA banned ephedra in December 2003 due to grave concerns about its safety. But while you won't find ephedra itself in diet-pill ingredient lists any longer, you will find ephedra-like compounds, including ephedrine, norephedrine, pseudoephedrine, methylephedrine and norpseudoephedrine, present in ma huang and other diet aids (often in combination with caffeine, which may exacerbate side effects). These compounds potentially present the same dangers as ephedra: elevated blood pressure, heart palpitations, insomnia, irritability, headaches, seizures, stroke, heart attack and even death. The safest route is to avoid all products that contain any of these substances.

Synephrine
After the FDA banned ephedra, diet-pill companies scrambled to find a possibly safer alternative. Enter synephrine, a substance made from the fruit of the citrus aurantium plant. Bitter orange, sour orange, green orange and zhi shi are other common names for this fruit. Synephrine acts almost the same way as ephedra does in the body, but with potentially fewer side effects like high blood pressure and increased heart rate. So far, clinical studies show that synephrine may in fact help reduce appetite and slightly increase metabolic rate, especially when combined with other stimulants such as caffeine or white willow. Obviously, anyone who has high blood pressure or other heart problems should not use any of these substances without prior approval from her doctor.

Caffeine
Caffeine, which may help some people lose weight because it slightly increases metabolism and may decrease appetite, hides in many diet-aid ingredients: Yerba mate, cocoa extract, white willow bark, gotu kola and guarana are some of the more common caffeine-containing substances used in diet pills. All of them have the potential to raise blood pressure levels, cause sleep disturbances and make your heart beat too rapidly.

Bladderwrack
Although it's thought to stimulate the thyroid and thereby pump up metabolism, there is absolutely no evidence that bladderwrack has any effect whatsoever on body weight. In fact, because it contains iodine, using bladderwrack may actually increase your risk of damaging your thyroid gland.

Garcinia cambogia
Garcinia, also called hydroxycitric acid, is a natural fruit acid extract from brindall berries. Experts disagree over its potential value in decreasing appetite and increasing metabolic rate. Since there are few side effects (the main one is nausea), it might be helpful for some people, but there isn't enough evidence supporting its effectiveness to recommend it across the board.

Green tea
It sounds too good to be true, but in this case there is research to back up the claims: The catechins in green tea help decrease your risk of cancer and heart disease, and promote weight loss. Drinking 4 to 10 cups of green tea per day probably won't cause any negative side effects, and it may help decrease appetite and increase metabolism. If you're sensitive to caffeine, look for decaffeinated green tea with standardized catechin content. If you take aspirin or anticoagulant medication, you should check with your physician before you drink green tea, as it can interfere with blood clotting times.

FAT BURNERS
Chromium
Chromium is a double-edged sword. Up to 90 percent of Americans don't get enough chromium from their daily food choices, and chromium supplementation may help reduce triglyceride and blood sugar levels. Some studies even show that 400 mcg of chromium per day can result in improved fat loss. Yet when taken in large doses, chromium picolinate is linked to DNA changes, kidney failure and muscle toxicity. Weighing all these factors together, taking 50 to 200 mcg of chromium per day appears safe and may be helpful for some people.

Pyruvate
Pyruvate has been shown to produce more fat loss than a low-calorie diet -- but only by about two pounds. However, the studies used 25 to 50 grams of pyruvate per day, while most diet pills contain no more than 250 to 1,500 milligrams per serving. There are 1,000 milligrams in one gram, so you'd need 100 servings of a product that contains 250 milligrams of pyruvate to get a dose that might potentially have some benefit. You're better off spending your money on a gym membership.

Quercetin
Quercetin is effective as a blood thinner and antioxidant, but its ability to increase the amount of fat your body burns and to promote weight loss is questionable. If you have trouble with blood pressure or blood clotting, definitely avoid any product that contains quercetin.

CARB BLOCKERS
Amylase inhibitors
Like high-protein diets, carb-blocking pills are one of the latest trends in weight loss. Most contain some type of amylase inhibitor, molecules that interfere with amylase, the enzyme produced by the body to break down carbohydrate. You can spot them in the ingredient list under phaseolus (sometimes listed as phaseolus vulgaris or phaseolamin), white kidney bean extract or wheat amylase inhibitor. The theory goes that if carbohydrate isn't broken down, it can't be absorbed and therefore can't supply calories to your body. While amylase inhibitors don't prevent the absorption of all the carbohydrate you eat, they can decrease the amount enough to produce weight loss. The downside? The side effects of undigested carbohydrate: gas, bloating and diarrhea.

FAT BLOCKERS
Chitosan
Made from crushed shellfish shells, chitosan is a main ingredient in many fat blockers. While it does absorb some of the fat you eat, the absorption comes at a price -- gas, bloating, diarrhea and decreased absorption of fat-soluble vitamins. Plus, human studies haven't shown improved weight loss as a result of using chitosan.

OTHER CLAIMS
DHEA
DHEA (or dehydroepiandrosterone) is a steroid hormone that may help with weight loss. However, doses large enough to produce weight loss also increase the risk of developing cancer. DHEA is contraindicated for anyone taking thyroid medication and, like any hormone, should only be used under a physician's supervision.

Gymnema
Gymnema is a plant used in India and Southeast Asia to reduce blood sugar levels. It may also decrease appetite and cravings for sweets in some people, which could possibly lead to weight loss. If you have diabetes, talk to your physician before you use any product that contains gymnema, as it may affect your blood sugar levels.

Psyllium
Psyllium is well known as a fiber supplement to help prevent constipation. (Metamucil is made of psyllium.) Its weight loss claim is that it decreases appetite by increasing the bulk in your food. But the only scientific study performed showed psyllium to have no effect on weight loss -- and using too much can cause gastrointestinal problems such as gas and bloating. You'll be better off simply choosing high-fiber foods such as whole grains, fruits, vegetables and legumes.