Weight Control and Diet
DescriptionAn in-depth report on losing and managing weight safely for health benefits.
Alternative NamesDietary Recommendations; Obesity
Many of the current drugs used for weight loss are effective, particularly when used appropriately along with additional measures, including exercise and behavioral modification.
The long-term effects of most of these medications have not been established. Most lose their effectiveness over time, thus requiring increased dosage, and some can become addictive. In addition, some of the psychostimulant agents have been associated with an increase in depression, which may be a particular problem, since depression is already common in obesity. (It is unclear if the newer agents, sibutramine and orlistat, have this effect.)
None of these drugs deals with the underlying problems that may be causing obesity. Unless specifically instructed by a physician, 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.
Over-the-Counter Drugs and Herbal Remedies
A 2001 study reported that 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 or so-called natural remedies. Buying unverified products over the Internet can be particularly dangerous.
Perhaps the best alternative advice for people who are overweight is to drink tea. Studies have indicated that regular tea drinking is associated with lower weight, particularly in people who drink it for years. Green tea specifically has been associated with increased energy expenditure. One study reported that people who took a green tea extract (Exolise) lost weight and reduced their waist size. Better evidence is needed, however, to confirm the results on this supplement.
Thermogenic Approach to Weight Loss. An approach to weight loss called thermogenic (also hepatothermic) therapy is based on the idea that certain natural compounds have properties that enable the liver to increase energy in the cells and stimulate the metabolism. Theoretically, the result would be fat loss. Among the natural 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, for example, is a common ingredient in many diet supplements (e.g., Xenadrine, Dexatrim, Acutrim Natural, 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 that theoretically could promote sterility.
Orlistat (Xenical) can help about one-third of obese patients with modest weight loss, and can assist in long-term maintenance of weight loss. It works by inhibiting the absorption of body fat (by about 30%) in the intestine. Studies indicate that between 50% and 80% of patients can achieve weight loss of 5% or greater, depending on other lifestyle changes. It does not work for all patients, however. In one survey of patients who took it, 10% gained weight or did not lose any and 43% lost less than 5%. Nevertheless, orlistat may delay or even prevent the onset or progression of diabetes and improve cholesterol levels, regardless of weight loss.
The drug 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 oily leakage of 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 agent.
Sibutramine (Meridia) keeps two important brain chemicals, serotonin and norepinephrine, in balance, which helps to increase metabolism. It causes a feeling of fullness and increases energy levels. It may be particularly useful for binge-eaters. Studies indicate that sibutramine is effective in achieving weight loss, although it slows considerably after the first three months. The agent also appears to improve cholesterol and lipid levels and have other effects that may benefit the heart.
Side effects are common. They include dry mouth, constipation, and insomnia, and in one study almost half the patients dropped out because of them. There have been reports of increases in heart rate and blood pressure, although a 2001 study indicates that blood pressure stabilize over time. At this time, people who have a history of high blood pressure, stroke, heart disease, or arrhythmias should not take this drug. People taking decongestants, bronchodilators (such as for asthma), monoamine oxidase inhibitors, or serotonin reuptake inhibitors should also avoid sibutramine.
Phentermine and Other Sympathomimetics. Sympathomimetics are agents that act like the neurotransmitter norepinephrine (a stress hormone) and act as stimulants in the brain. Some are approved for treating obesity, but only for short-term use. They include phentermine (Ionamin, Adipex, Fastin), benzphetamine (Didrex), and phendimetrazine (Adipost, Bontril, Melfiat, Plegine, Prelu-2, Statobex). Phentermine is the most commonly prescribed appetite suppressant and is less expensive than orlistat or sibutramine. Its effects are not long lasting, however. Any sympathomimetic can raise blood pressure. In addition, such drugs are 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 with fenfluramine (Fen-Phen).
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 elevate mood and produce some modest weight loss over the short term, but present serious risks of addiction, agitation, and insomnia.
Ciliary Neurotrophic Factor. An agent derived from ciliary neurotrophic factor (Axokine) signals the brain to suppress appetite. It is proving to be effective in achieving weight loss, and also improves cholesterol, lipid, and glucose levels regardless of food intake. The agent, then, may be particularly helpful for people with type 2 diabetes. It is currently in late trials.
Zonisamide. Zonisamide (Zonegran) is an anti-seizure agent that is also being investigated for weight loss. In one study, patients who took it lost more weight than those on placebo. Zonisamide increases the risk for kidney stones, which can be reduced with increased fluid intake and citrate. It has also been associated with reduced sweating and a sudden rise in body temperature, especially in hot weather. Other side effects include dizziness, forgetfulness, headache, and nausea.