Do Diet Pills Really Work? - Page 4

Glucophage (metformin) and Byetta (exenatide)

THE SKINNY: These two diabetes drugs are also being prescribed by obesity specialists to aid weight loss in diabetics. Glucophage lowers glucose levels and increases insulin sensitivity, so you'll be less hungry and less likely to overeat, explains Cederquist. It's often used with Byetta, an injectable diabetes drug that delays the movement of food from your stomach into your small intestine, so it may extend fullness and help you to eat less. About 80 percent of women who took metformin while following a modified carbohydrate diet lost about 10 percent of their body weight within a year, a New York Medical College study found. And just over 90 percent of them had kept the weight off four years later. According to another study, diabetics who had a weekly injection of Byetta alone lost 8 pounds after 15 weeks.

THE RISKS: Both drugs can initially cause nausea, upset stomach, and diarrhea — which may be partly responsible for weight loss, says Isaacs.

IS THIS PILL FOR YOU? These medications are for people who are diabetic or those who are overweight (having a BMI of 25 or more) and also have elevated blood sugar levels and diabetes. Since both drugs are approved to treat diabetes, they're more likely than the other diet pills to be covered by insurance. "We also use these drugs in women who have polycystic ovarian syndrome (PCOS), a hormonal condition linked with insulin resistance that may cause weight gain, acne, and irregular periods," says Fernstrom. "Once we get sufferers' insulin under control, their PCOS symptoms improve and they often lose weight."

What about supplements?

Think these "natural" weight-loss aids are a safe option? Think again.

You've heard and seen their benefits extolled on infomercials — from "lose 30 pounds in 30 days" promises to miraculous before-and-after photos — and they're sold everywhere, from your local drugstore to the Internet. But just because these dietary or weight-loss supplements claim to be made with herbs and other naturally occurring ingredients doesn't mean you can take them without worry. "Dietary-supplement companies aren't required to show clinical data on their efficacy and safety to the FDA, which means we have no idea whether they work or if they're safe," says Michael Steelman, M.D., an obesity specialist in Oklahoma City.

Take bitter orange extract, a substance that has replaced ephedra as an ingredient in many weight-loss supplements. (Ephedra was banned in 2004 after causing more than 16,000 adverse events, including several cases of stroke and death.) Two products containing bitter orange — Advantra Z and Xenadrine EFX — were found to increase heart rate, and Xenadrine increased blood pressure by 7 percent to 12 percent in participants in a University of California San Francisco study. What's more, bitter orange doesn't appear to help people lose weight, according to a research review. And while there may be some truth to the weight-loss promises of hoodia, a cactuslike plant said to be used by African bushmen to stave off hunger, a lot of the products that claim to be made with hoodia don't actually contain much or any at all, says Lona Sandon, R.D., a spokesperson for the American Dietetic Association. Hoodia's a protected plant, and many experts suspect that companies replace some or all of it with another species of the same plant. Whether hoodia itself is harmless is unclear, but products that use it often contain other potentially dangerous ingredients, such as bitter orange.

To find out more about these and other common supplement ingredients such as hydroxycitric acid (HCA, found in Hydroxycut) and chromium (found in Trimspa), visit webmd.com.

There are two supplements that may have some safe body fat– and weight-loss potential: green tea extract and conjugated linoleic acid (CLA). Green tea contains EGCG, an antioxidant that may help boost metabolism, according to some studies. CLA, found naturally in dairy, was shown to reduce body fat in one small study, though participants' weights stayed the same. But the amounts found in EGCG and CLA supplements vary and some may not be effective, says George Blackburn, M.D., an obesity specialist at Harvard Medical School. Instead, he suggests getting these compounds through food, whether by including green tea at breakfast or by adding an extra glass of skim milk to your daily diet.