As our country reaches a point where approximately 60 percent of us are overweight and at least 30 percent of adults are classified as obese, pharmaceutical companies’ quest for a true appetite suppressant seems like the new search for the Holy Grail.

p>As a physician, I generally discourage patients from using weight-loss products because they haven’t been proven effective. Studies of highly promoted over-the-counter appetite suppressants show that the difference in weight loss after one year between those taking the medication and those taking the placebo was only 3 pounds.

That translates into $1,000 in medication expenses for 3 pounds, based on the average cost of using an appetite suppressant for one year.

There is now a great deal of interest in the endocannabinoid system and how this group of receptors monitors our food intake. There are cannabinoid receptors in the brain and other organs that increase our appetites when they’re stimulated.

It makes sense that if we can inhibit these receptors – using receptor antagonists, a substance that blocks a biological response – we can decrease appetite. Studies performed with a mouse that lacks these receptors found it is leaner, eats less and gains less weight after a high-fat meal than a standard mouse.

Cannabinoid receptors are believed to exist and regulate energy balance in other organs such as the liver, muscles and pancreas. For this reason, people who think they’re heavy due to their genes may be correct. Higher levels of endocannabinoids have been found in obese subjects – as well as fewer enzymes that naturally break down endocannabinoids.

The first breakthrough using a receptor antagonist came by accident. Scientists were testing a drug for the treatment of schizophrenia and found that treated subjects lost a significant amount of weight. The drug, called Rimonabant, was studied for two years and the results were released in 2005. People who took the drug lost 10-15 pounds more than people who took the placebo. High-density lipoprotein (HDL), better known as “the good cholesterol,” went up; triglycerides, blood pressure and cigarette cravings went down; and insulin levels normalized.

Before you rush over to Europe – the only place you can get Rimonabant, marketed as Acomplia – you should be aware that it has some disturbing side effects. Cannabinoid receptors are also involved with the dopamine system in the brain, which controls pleasure and mood. Rimonabant has been shown to block this system, resulting in some cases of anxiety, depression and other serious psychiatric disorders.

Because of these negative outcomes, the U.S. Food and Drug Administration has not authorized the drug Rimonabant for use in this country. But all is not lost. Because many of the benefits can be achieved by blocking the receptors in organs outside the brain, research is ongoing to create a receptor antagonist that does not cross the blood-brain barrier and therefore would not have the psychiatric side effects.

When that happens, buy stock. Until then, I recommend you use your $1,000 for a gym membership.

Dr. Steven Howard is a family medicine physician at the Palo Alto Medical Foundation’s Redwood City Center. The Palo Alto Medical Foundation and column editor Arian Dasmalchi provide this monthly column.

For more information, visit www.pamf.org.

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