February 25, 2009

Study Questions Long-Term Success Of Weight-Loss Drug

A new study suggests that many people taking the weight-loss drug orlistat, sold under the prescription name Xenical, do not maintain the necessary dietary changes for the treatment's success.

Orlistat aids weight loss by blocking the intestinal absorption of dietary fat. Those taking the drug are advised to limit their fat intake to less than 30 percent of their daily calories because higher amounts increase the risk of gastrointestinal side effects such as incontinence and loose stools.

Some have argued that orlistat may, in part, aid weight loss because those side effects encourage people to maintain a low-fat diet over the long run.

However, the new small study found that orlistat users had a slightly higher average fat intake than non-users over a two month time period.  Furthermore, that average exceeded the recommended 30-percent guideline.

The study, conducted by Dr. Mette Svendsen and colleagues at Ulleval University Hospital in Oslo, Norway, involved 44 obese men and women who had participated in a three-year clinical trial comparing orlistat with a placebo, in addition to changes in lifestyle.  At the end of the trial, participants could chose whether or not to continue taking the weight-loss drug.  

Two months later, Svendsen's team queried users and non-users about their dietary habits, and found that orlistat users were getting an average of 33 percent of their daily calories from fat, compared with 28 percent among non-users.

Svendsen's team concluded that orlistat did not have a "policing effect" on patients' dietary choices, something that "may hamper the effect of the drug."

Larger studies are needed to examine the habits of those who choose to take orlistat for long-term weight-loss maintenance, the researchers said.

The study was published in the Journal of Human Nutrition and Dietetics.


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