Americans currently spend billions of dollars every year on weight-loss supplements. Although we would not buy a car or a dinner without knowing a few details, many who purchase these supplements have little or no idea what is in them, or what independent reports say about their safety and effectiveness.
Even though the FDA (Food and Drug Administration) has charged some companies for using banned ingredients and the FTC (Federal Trade Commission) has successfully prosecuted merchants who made illegal claims, the same products, or almost identical versions, still remain available for the consumer.
Some weight loss supplements contain ingredients which are meant to suppress appetite. Caffeine and its herbal counterparts, guarana, bitter orange and yerba maté, also ephedra (ma huang), fall into this category.
Animal studies suggest that they may slightly suppress the appetite, but the limited studies on humans lasted only a few months. All these ingredients stimulate the nervous system so they generally produce only side effects like headaches, insomnia, raised blood pressure and heart palpitations.
Product descriptions can be deceptive: Weight-loss supplements labeled ephedra- or “caffeine-free” may contain other ingredients listed earlier in this article, which may pose the same health risks. Although ephedra (ma huang) has been banned by the FDA, you may still see it included in some supplements.
In a summary of more than 50 trials, this substance created a 2 - 3.6 fold increase in the risk of psychological, heart and digestive system problems.
Supplement manufacturers claim that other ingredients promote weight loss by speeding up the body’s metabolism.
For example, EGCG (epigallocatechin gallate), a phyto-chemical found in green tea, is being studied for its potential to reduce the risk of cancer. Some initial studies suggest it might slightly increase the rate at which calories burn. Now it can be found in many weight-loss supplements and “weight-loss vitamins.” However, since only very short initial studies have so far been performed, the body might adapt to EGCG, reducing its effect over time.
Furthermore, the weight loss benefit seen with EGCG amounts to about 60 to 70 calories a day. This small difference is more likely to help prevent gradual yearly weight gain rather than reverse excessive weight gain.
Third, the effect of EGCG appears to depend on the dosage. Supplements containing 30 to 40 mg of EGCG, commonly seen in these products, may not have the same effect as a dose of over 250 mg used in the studies.
Few significant effects
Supplements may also contain ingredients that producers say will block the absorption of fat or carbohydrates. Chitosan is a common example, and some preliminary studies made it appear promising.
However, several controlled studies found that chitosan had no significant effect on fat absorption. In the most recent study, men would need seven months to lose one pound of body fat. There was no fat loss for women.
Another group of ingredients are said to increase the feeling of fullness and decrease eating. Guar gum appears safe for this purpose, but 11 well-controlled studies demonstrate that it has no benefit as far as weight loss is concerned.
Psyllium can help control blood sugar and blood cholesterol, but studies do not support its reputed ability to reduce eating and assist weight loss.
There are more than 50 individual supplements and 125 combination products now available for people who wish to lose weight. Yet a Harvard Medical School review of these products that set standards for safety, quality and effectiveness concluded that none of them met all three standards.
Future research may identify some safe and effective ingredients for weight loss, but for the time being it seems smarter to invest instead in walking shoes, a gym membership, or healthier food.
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