Phentermine vs. Placebo - Does Phentermine Really Work?

Adult obese persons taught in dietary management and treated with "anorectic" drugs, lose more weight on average than those treated with placebo and diet, as determined in relatively short-term clinical trials.

One study, done by McMaster University, found that phentermine versus placebo caused modest weight loss in adults more than 20% overweight. Limited evidence suggests that phentermine, compared with placebo, resulted in modest weight loss over short periods in people more than 20% overweight. They found no evidence of serious adverse events associated with phentermine. Phentermine given alone has not been associated with valvular heart disease.

This study included 108 people, all more than 20% overweight, who were split into two groups. Both of these groups were put on a restricted diet of 1000 calories a day. Half were given 30 mg of Phentermine a day, the other half given the placebo. After 9 months of this calorie restriction, placebo or Phentermine, the study found that Phentermine increased weight loss by 5 ½ pounds. While this amount may not be significant, it does prove that Phentermine most certainly aids in weight loss.

In another clinical trial, it was stated that over the course of 36 weeks, another 108 obese women were studied. The women were randomized to diet therapy and either treated with daily Phentermine, daily Phentermine every other month alternating with daily placebo every other month, or daily placebo. Approximately two-thirds of the 108 women enrolled completed the study; among these women, the groups receiving either continuous or alternating phentermine therapy lost about 13% of their initial weight, compared with a 5% weight loss in the placebo group.

In comparison to placebo studies, it's obvious of the added effect of Phentermine when used with a restricted diet. Through these studies, the only long term, adverse effect that was found by the second clinical trial given, was one woman using the alternating months of Phentermine had an increase in blood pressure after the trial was over. While this was the case, it is still not recommended for extreme long term use because of the unknown effects it may have.