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Phentermine Diet Pills to Lose Weight

Jun 15, 2011 | By Beth Spicer
Phentermine Diet Pills to Lose Weight
Photo Credit Pills image by explicitly from Fotolia.com

Phentermine, or phentermine hydrochloride, is the generic name for one of the most popular and effective prescription weight loss medicines available. This drug has been on the market since the late 1950s and has remained one of the most commonly prescribed bariatric pharmaceuticals. It remains popular due to its low price, its long history of safe use, and because it is quite effective at assisting in weight loss efforts.

Mechanism of Action

Phentermine acts as a sympathomimetic amine in the body, which means simply that it increases the body's release of catecholamines, according to the National Institutes of Health, thereby causing both a decrease in appetite and an increase in the body's expenditure of energy. Thus, when taking this drug, you will probably feel less hungry, but at the same time, more energetic and alert, and your body will be burning more calories, even when you are resting. Weight loss occurs because of this combination of effects---less input and greater output.

Efficacy Study 1

For a drug that's been around as long as phentermine, there are actually relatively few studies, especially recent ones, demonstrating its effectiveness. However, those that do exist clearly show it improves weight loss over placebo treatments.

A double-blind trial of phentermine conducted back in 1968 and printed in the "British Medical Journal," involved three groups of 36 women. Continuous use of phentermine at 15 mg per day for 36 weeks resulted in a 27 lb. average weight loss, or 13 percent of starting weight. Patients who were given placebo treatments only lost 10.5 lbs., about 5 percent of their starting weight. Interestingly, patients whose treatment alternated between active and placebo each month achieved the highest loss of all at 28.7 lbs., or 13.4 percent. All of these patients were following a similar diet of around 1,000 calories, so these results confirm that phentermine does indeed induce a greater loss than diet alone.

Efficacy Study 2

In a more recent trial conducted in Korea in 2005, phentermine was again tested against placebo, this time at a dosage of 30 mg per day in both men and women. After 14 weeks, the treatment group in this study lost 16.5 lbs. while the placebo group lost only 6.8 lbs, a difference that was statistically significant. The treated patients also saw a statistically greater decrease in their waist circumference.

Duo Effects

While phentermine's appetite-reducing effects are most often credited for its usefulness as a weight-loss aid, that characterization sells the drug short. As these studies show, even when following the same diet, drug users lose much more weight than on diet alone. To that point, consider a 1981 study in which mice were tested using a variety of appetite-suppressing drugs. Of these drugs, phentermine was actually the least effective in reducing appetite, causing a mere 6.6 percent decrease in intake relative to control mice, yet ended up with 16 percent less body fat than the controls according to a report in the "American Journal of Clinincal Nutrition." While drug effects on humans and mice cannot be compared directly, this certainly shows that phentermine's effects are not solely due to appetite suppression.

Conclusion

If you are considering using the diet drug phentermine to assist with weight loss, you should be aware that the drug has been found to have some side effects, such as dry mouth and insomnia, but these effects are usually mild and transient. Overall, the research indicates that your weight loss efforts should be enhanced by the combination of appetite suppression and increased energy output caused by the sympathomimetic effects of the product.

References

Article reviewed by GlennK Last updated on: Jun 15, 2011

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