There are several different drugs used for weight loss. Unless specifically instructed by a doctor, people should use non-drug methods for losing weight. Except under rare circumstances, pregnant or nursing women should never take diet medications of any sort, including herbal and over-the-counter remedies. While weight loss drugs in general have shown some benefit, the overall weight loss achieved is generally limited. In addition, people will usually regain the weight when they discontinue the medication.
Over-the-Counter Weight Loss Products and Herbal Remedies
About 7% of American adults use nonprescription weight-loss products. People must be cautious when using any weight-loss medications, including over-the counter diet pills and herbal remedies. Buying unverified products over the Internet can be particularly dangerous.
Green Tea. Some studies have suggested that regular tea drinking is associated with lower weight, particularly in people who drink it for years. However, better evidence is needed to confirm the results on this supplement.
Thermogenic Approach to Weight Loss. An approach to weight loss called thermogenic (or hepatothermic) therapy is based on the claim that certain natural compounds have properties that enable the liver to increase energy in cells and stimulate metabolism. Theoretically, the result would be fat loss. Among the substances used in such products are EPA-rich fish oil, sesamin, hydroxycitrate, pantethine, L-carnitine, pyruvate, aloe vera, aspartate, chromium, coenzyme Q10, green tea polyphenols, aloe vera, DHEA derivatives, cilostazol, diazoxide, and fibrate drugs.
Nearly all the current over-the-counter dietary aids contain some combination of these ingredients. There is no evidence that any of these ingredients can produce weight loss, and some may even have harmful effects.
Chromium is a common ingredient in many diet supplements (such as Xenadrine, Dexatrim, Acutrim Natural, and Twinlab Diet Fuel). It is claimed to specifically promote fat loss, rather than lean muscle loss. Some evidence suggests that niacin-bound chromium may improve insulin sensitivity. On the negative side, animal studies have suggested that chromium may have damaging effects on genetic materials in cells. In theory, this could increase the risk of cancer.
Warnings on Some Ingredients in Over-the-Counter Diet Products
Ephedra, Ephedrine, and Ma Huang. The FDA does not allow the sale of drugs that contain ephedrine. In May 2004, the FDA banned the sale of dietary supplements that contain ephedra (also called Ma Huang). Ephedra can cause serious side effects, including strokes and heart attacks.
Brazilian Diet Pill. The FDA has warned consumers not to buy a product known as the "Brazilian diet pill." This product is labeled as a dietary supplement, but contains several chemicals found in powerful prescription drugs. The products are also known as Emagrece Sim and Herbathin dietary supplements.
Conjugated Linoleic Acid (CLA). Conjugated linoleic acid is found in many dietary products (such as Biosculpt Liquid, Body Success, and GNC Optibolic Body Answers Dietary Formula). There is no evidence that it produces weight loss. Furthermore, there is some concern that CLA might increase insulin resistance and a dangerous inflammatory response in people with obesity.
Tiratricol. Over-the-counter products containing tiratricol, a thyroid hormone, have been sold for weight loss. Such products may increase the risk for thyroid disorders, heart attack, and stroke. Tiratricol is also known as triiodothyroacetic acid or TRIAC.
Laxative Actions in Natural Substances. Many dietary herbal teas contain laxatives, which can cause gastrointestinal distress, and, if overused, may lead to chronic pain, constipation, and dependency. Rarely, dehydration and death have occurred. Some laxative substances found in teas include senna, aloe, buckthorn, rhubarb root, cascara, and castor oil.
Guar Gum. Some fiber supplements containing guar gum have also caused obstruction of the esophagus and gastrointestinal (digestive) tract.
Chitosan. Chitosan, a dietary fiber from shellfish, prevents a small amount of fat from being absorbed in the intestine. Well-conducted studies, however, have not found it to be effective. Products containing it include Natrol, Chroma Slim, and Enforma. People who are allergic to shellfish should not take these supplements.
Plantain. Dietary remedies that list the ingredient plantain may contain digitalis, a powerful chemical that affects the heart. NOTE: This substance should not be confused with the harmless banana-like plant also called plantain.
Orlistat (Xenical) can help about one-third of obese patients with modest weight loss and can help in long-term maintenance of weight loss. It works by slowing the absorption of fat in the intestine (by about 30%). The average weight-loss attained is around 6 lbs. with use of this drug. However, many people regain a significant portion of this weight within 2 years. While it does not work for all patients, orlistat may delay or even prevent the onset or progression of diabetes, and improve cholesterol levels, regardless of weight loss.
Orlistat can cause gastrointestinal problems and may interfere with absorption of the fat-soluble vitamins A, D, and E and other important nutrients. The most unpleasant side effect is leakage of oily feces from the anus. Restricting fats can reduce this effect. People with bowel disease should probably avoid it. In spite of these side effects, most patients are able to tolerate this medicine.
There is an approved over-the-counter version of orlistat. Sold under the name alli, it is available at half the prescription strength of Xenical. Those eager to use the alli should consider its cost (around 100 per month) and modest benefits compared with its side effects, most commonly oily diarrhea.
Note: This pill, which prevents fat absorption from food, also increases the risk of not absorbing important nutrients from food while using it. The FDA recommends taking a daily multivitamin supplement when using alli.
The weight loss drug sibutramine (Meridia) is no longer on the market because of a higher risk for heart attack and strokes.
Phentermine and Other Sympathomimetics. Sympathomimetics are drugs that act like the stress hormone (and chemical messenger) norepinephrine. These medications act as stimulants in the brain. Some are approved for treating obesity, but only for short-term use of 12 weeks or less. Average weight-loss has been in the range of 7 lbs. over the short-term. These medicines include:
- Phentermine (Ionamin, Adipex-P, Fastin)
- Benzphetamine (Didrex)
- Phendimetrazine (such as Adipost, Bontril, Melfiat, Plegine, Prelu-2, and Statobex)
Phentermine is the most commonly prescribed appetite suppressant, and is less expensive than orlistat or sibutramine. Its effects are not long lasting, however. It can also raise blood pressure. In addition, phentermine is associated with depression, which is already a problem in many cases of obesity. A combination (Phen-Pro) containing phentermine and the antidepressant fluoxetine (Prozac) is being investigated to help reduce this problem. Note: Neither phentermine nor such combinations are associated with the heart problems linked to the previous phentermine combination known as Fen-Phen (phentermine and fenfluramine).
Amphetamines. The amphetamines dextroamphetamine (Dexedrine), methamphetamine (Desoxyn), and phenmetrazine (Pleudin) are powerful stimulants. They were used most often in the past but are no longer prescribed for weight loss. These drugs improve mood and produce some modest weight loss over the short term, but carry serious risks of addiction, agitation, and insomnia.
Topiramate. Topiramate (Topamax) is an anti-seizure medication being investigated for weight reduction. Several clinical trials have reported that obese patients with type 2 diabetes given topiramate lost more weight than those receiving placebo. Weight loss was sustained for up to 1 year. The drug is also being studied for binge-eating disorders associated with obesity. However, psychiatric and neurological side effects may prevent topiramate from being used regularly.
Cellulite-Removal Creams. Many women try to reduce fat in their thighs (cellulite) with creams that contain aminophylline (such as Skinny Dip, Thermojetics Body Toning Cream, and Smooth Contours). Studies provide no evidence that these creams are effective. Their apparent effect on fat may simply be from narrowing blood vessels and forcing water from the skin, which could be dangerous for people with blood flow problems.
Endermologie. Endermologie uses motorized rollers and regulated suction to smooth out cellulite.