Using a diet drug to enhance weight loss efforts is often seen as a cop-out on the stressful path of dieting and exercising, but the scientific facts show that weight loss medications such as phentermine, also known as phentermine resin and phentermine hydrochloride, do improve your chances of losing weight and your weight loss results. Phentermine has been available since the late 1950s, and research studies show that it is both safe and effective when used with a doctor's supervision.
How The Drug Works
According to the National Library of Medicine's phentermine page, the primary mode of action of this drug is that of a sympathomimetic amine. That means phentermine increases the release of the catecholamines epinephrine and norepinephrine. Higher amounts of these catecholamines cause some lessening of appetite and slight increase in energy expenditure. That means you will feel less hungry and have greater energy and alertness. Weight loss results from this combination.
Average Weight Loss
The rate at which you will lose weight varies significantly from person to person, depending on a number of factors: your diet, your drug dosage, your starting weight, your gender, and a number of other genetic and environmental variants. It is also true that the rate will vary over time, as is the case with all weight loss methods. Usually, people lose the most weight in the first three months, and then it tapers off until little or no more weight is lost after six to seven months.
Phentermine Study in Korea
The most recently reported trial of phentermine was conducted in Korea in 2005 and reported in "Yonsei Medical Journal." In this study, 34 male and female patients were put on a 1,500 calorie daily diet and given a daily dosage of 37.5 mg of phentermine hydrochloride . The participants lost an average of 16.5 lbs. during the 14 weeks of the study, which is about 5 lbs. per month.
UCLA Phentermine Study
In 2003, a study was published out of UCLA, which compared the results for subjects treated with either phentermine alone or phentermine combined with fenfluramine---a combination which is no longer available. In the phentermine-only arm, 188 male and female subjects were given 8 to 30 mg of phentermine per day. They consumed a very low calorie diet along with the drug, taking in 500 to 800 calories per day. After 12 weeks of study, the women lost 17.6 lbs. on average, while the men lost 21.3 lbs. This makes a monthly average of 6.3 lbs. and 7.6 lbs.
British Medical Journal Phentermine Study
A much older study, published in 1968 in "The British Medical Journal," gave results of a double-blind clinical trial of phentermine. Three groups of women, 36 to a group, were compared for their results using a 1,000 calorie diet and either placebo or 15 mg of phentermine per day. Of the two drug groups, one used phentermine continuously, and the other used it every other month. While the placebo group lost only 10.5 lbs over the 36 weeks of the trial, the phentermine groups both lost more than twice that amount. The continuous use group lost 27 lbs., or 3.2 lbs. per month, and the intermittent use group lost 28.7 lbs, or 3.4 lbs. per month.
Conclusion
If you are thinking of trying phentermine to assist you in your weight loss efforts, you should recognize that it does have potential for negative side effects, though, as one researcher stated in the Korean study, the incidence of serious side effects is probably about 15 in 1,000 users. Most side effects are mild and transient, such as dry mouth or insomnia. Evidence indicates that using phentermine in conjunction with a low-calorie diet should yield approximately 3 to 6 lbs. of weight loss per month for women, and 5 to 8 lbs. for men.
References
- U.S. National Library of Medicine DailyMed: Phentermine Hydrochloride Capsule
- "Yonsei Medical Journal"; Effects on Weight Reduction and Safety of Short-Term Phentermine Administration in Korean Obese People; Kyoung Kon Kim; Oct. 31, 2006
- "Current Therapeutic Research": Body weight loss with phentermine alone versus phentermine and fenfluramine with very-low-calorie diet in an outpatient obesity management program: a retrospective study; Zhaoping Li; July 2003
- "British Medical Journal":Comparison of Continuous and Intermittent Anorectic Therapy in Obesity; J.F. Munro; Dec. 10, 1968
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