What's the Skinny on Diet Pills

I don't advocate diet pills. There are no short cuts to long-term weight loss. However, a frequently asked question, especially during this time of the year, is what's new with diet pills.

A few years ago, the combination of phenteremine ad pondimin,( phen-fen), was quite popular. Both medications were effective appetite suppressants and they helped patients lose weight faster. However, their use was discontinued when they were associated with valvular heart disease.


Current medications which are available include orlistat (Xenical, Alli) and sibutramine (Meridia). Orlistat interferes with absorption of fats by interfering with one of the digestive enzymes in the intestines. Diarrhea, gas, and dyspepsia are the most common side effects. It results in 3 kg. (6.6 lbs.) more weight loss than placebo after 1 year.

Sibutramine suppresses appetite by working on the appetite control centers of the brain. It affects the processing of certain brain hormones such as serotonin. It was shown to result in 4.5 kg (9 lbs.) more weight loss than placebo in 1 year. The side effects include dry mouth, insomnia, and nausea.

There are several other medications which are currently under investigation but which have not yet been approved in the United States. Many of these work by by decreasing the activity of the endocannainoid system (EC). This is the same brain circuit that makes people hungry when they smoke cannabis (marijuana).

The EC system is a recently recognised physiological system that includes receptors such as the CB1 receptor and and which has been shown to play an important role in regulating body weight and in controlling energy balance. Rimonabant (also known as Zimulti, Acomplia or Slimona) has already been approved in Europe. It works by blocking the CB1 cannabinoid receptor. In one study it stopped food craving and helped overweight people lose an average of 20 pounds. It also was found to decrease craving for certain addictive substances. The side effects associated with this medication have been depression and anxiety.

While these medications may have a role in short term treatment of obesity, they are not recommended for long term weight management. Each medication has its own profile of side effects. Exercise and proper nutrition remain the safest regimen although admittedly not the most immediately gratifying solution.

References: Drugs Fut 2007, 32(9): 766
Photo: courtesy of La Verne Magazine