As much as people may dream of the pill that lets them lose weight without diet or exercise -- the claim of countless hucksters and infomercials -- none of these drugs works that way. Studies have shown that these drugs really only work in conjunction with lifestyle changes.
The amount of weight that people lose on weight loss drugs varies: Some people have great success and some don't. On average, people don't lose more than 10% of their baseline weight -- that's a 20-pound weight loss for a person who is 200 pounds. Generally, people lose the most weight in the first three to six months on the drugs and then plateau.
A 10% weight loss may not sound like a lot. But experts stress that modest weight loss -- even 5% -- can make a big difference in your risk of developing disease. Many studies have shown the effectiveness of weight loss drugs in reducing health risks. For instance, a recently published study of Xenical found that it could cut the risk of type 2 diabetes by 37%.
How Long Would Someone Need to Use Them?
Studies have shown that if a person on one of these medications doesn't lose 4 pounds in the first four weeks, then it can probably be stopped; it's unlikely that the drug is going to work. If someone does have success with a drug, it should probably be taken long term. Weight loss drugs are not a quick fix. Instead, they're more like medication for high blood pressure or diabetes, Wyatt says. Obesity really is a chronic disease.
"The physiology that causes someone to become obese doesn't go away," says Wyatt. Stopping the drugs usually means that the weight will come back. And losing the weight doesn't matter as much as keeping it off. If you lost 20 pounds but regained it all within the year, it's not going to help all that much.
Long-term treatment doesn't mean that people will necessarily be taking the same weight loss drug every day for the rest of their lives. Instead, it's possible that someone might switch between Xenical, Meridia, or other drugs.
It may also be possible for people to take breaks in treatment. "Weight isn't like blood pressure," says Wyatt. "If you stop taking your blood pressure medication, it goes up within a few days. Regaining weight takes longer." So far, studies have not shown any advantages to using weight loss drugs periodically. But as researchers learn more about how to best use these medications, it may be a possible form of treatment in the future, Wyatt says.