There is no way to know whether a dietary supplement off the shelf is safe or even pure. Until and unless a disaster like ephedra comes to federal attention, the industry is essentially self-regulated. Even the Federal Trade Commission, which can prosecute for false advertising, has been unable to keep up with the proliferation of products and undocumented claims.
Saper, among others, has examined popular supplements. A combined analysis of 11 trials of the soluble fiber guar gum showed no benefit. For chromium and ginseng, he found no scientifically structured trials that showed a difference in weight loss between the supplement and a placebo. And chronic use of chromium may cause kidney and muscle damage.
Supplements with HCA, from the tropical fruit mangosteen, reported to interfere with fat synthesis and speed fat breakdown, showed contradictory results in different human tests. CLA, a trans fatty acid that reduced fat deposition in mice, produced no change in body fat in a 12-week trial of 60 patients, but caused gastrointestinal distress and may raise cholesterol and worsen insulin resistance.
Chitosan seemed safe in short-term studies but "is likely ineffective for weight loss," Saper wrote, based on five clinical studies. It can cause constipation, bloating and other gastrointestinal symptoms, the Mayo Clinic reported.
One substance, pyruvate, showed a small benefit over a placebo, about 1.13kg in six weeks. It is frightfully expensive and takes a week or two before results are seen.
Green tea extract, said to speed metabolism and suppress appetite, is supported by limited evidence of effectiveness and can cause vomiting, bloating, indigestion and diarrhea, as well as jitteriness and palpitations from its caffeine.
In addition to possible risks associated with single-drug supplements, many products combine several ingredients that could interact to add hazards. Some ingredients in weight-loss supplements can interact with prescription and over-the-counter remedies, possibly resulting in toxic effects.
Hoodia, a supplement derived from a South African cactus, may indeed suppress appetite. But the real thing is very hard to obtain, and most of the products sold in stores and on the Web contain little or none of the effective extract.
The list could go on and on, but I think you get the point. There is no quick fix for weight loss using over-the-counter diet pills.
Several prescription drugs have received FDA approval. Orlistat, sold as Xenical, reduces the absorption of fat from foods. It can cause gastrointestinal distress and disrupt absorption of fat-soluble vitamins.
Sibutramine, sold as Meridia, revs up metabolism and energy levels and creates a feeling of fullness. Common side effects include dry mouth, constipation and insomnia. Meridia should not be used by people with cardiac risk factors and those who use bronchodilators, take decongestants or use MAO inhibitors or SSRI's for depression.
A number of products called sympathomimetics are approved for short-term use. All can raise blood pressure. They include phentermine, sold as Lonamin, Oby-Cap, Adipex and Fastin; mazindol, Mazanor and Sanorex; benzphetamine, Didrex; diethylpropion, Tenuate; and phendimetrazine, Adipost, Bontril, Melfiat, Plegine, Prelu-2 and Statobex. Any may help a dieter start, but because of side effects, long-term use is generally not recommended.
RSS