Obesity drugs alone won't do it

By Christy Oglesby
CNN

ATLANTA, Georgia (CNN) -- The pitch is all in the verbs: Absorb. Block. Burn. Metabolize. The names and promises of obesity drugs make it sound as if the pills will do all the work -- consuming, searing and routing fat right out of a body.

Hardly.

"I know of no drugs that absorb fat. It would be nice to say there's this drug that's a sponge that will suck it up, but it won't," said Dr. Arthur Frank, medical director of the weight management program at George Washington University in Washington, D.C.

And the obesity drugs that do increase metabolism or block the absorption of fat also require work and diet modification. None of the obesity drugs on the market is particularly potent, experts said. And they won't work without a decrease in food and fat consumption coupled with an increase in physical activity.

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"They cannot be used exclusively. That's a common misconception," said Chris Rosenbloom, a registered dietitian and chair of the nutrition department at Georgia State University in Atlanta, Georgia. "You can out-eat any of these drugs."

So what's the point of spending $50 to $100 a month (or more if insurance won't cover the prescription) on pills that may only yield weight loss of a pound a week?

Obesity drugs can help people who are morbidly obese -- 300 to 400 pounds -- and are incapable of minor physical activity or walking because of excess weight, Rosenbloom said.

"Sometimes medication can help jump-start that weight loss... or provide a psychological boost when you start to see some results," she explained. "Surgery for someone who is morbidly obese is another option. I am not adverse to any of those strategies."

For those who opt for a pharmacological approach, obesity drugs fall into two categories -- those that prevent the absorption of some fat and those that suppress appetite. The former inhibit the intestinal enzyme that metabolizes fat, so that the fat passes undigested through the bowels. Xenical is an example. Appetite suppressants, such as Meridia, affect hunger control centers in the brain.

However, hunger is not the only trigger for eating, experts said.

"You have a lot of very powerful forces that drive your eating. Our culture doesn't just use food for nutritional reasons," said Frank. "The idea that eating is merely a concept of choice is a naive analysis of why people eat."

Genetics and faulty metabolism also are obesity factors, Frank said, and some people eat for comfort, so behavior restructuring therapy may be useful in combination with obesity drugs.

The drugs' side effects appear to be minimal, the doctors said. Some appetite suppressants can create psychological dependence because they contain phentermine, which is chemically similar to amphetamines. Others can cause insomnia, drowsiness, irritability or depression.

Drugs that prevent fat absorption can cause cramping, diarrhea, flatulence and intestinal discomfort. And people who consume excess amounts of fat while taking those drugs may experience greater intestinal discomfort, Rosenbloom said.

Overall, though, the risks involved in taking the drugs are minimal, added Frank. "There's a lot more risk with uncontrollable obesity."