Weight Loss Drugs for Obesity, Helpful Treatment (cont.)

Weight and Genetics

Wyatt observes that, from an evolutionary standpoint, there's an advantage to building up excess fat. For most of human history, people were subject to periodic famines. Those who retained excess fat might have been more likely to survive a famine than those who didn't. The problem is that this evolutionary adaptation -- that may have saved the lives of our ancient ancestors during difficult times -- is hurting us now.

This is not to say that having a predisposition to being obese means you will be obese. The fact that Americans are heavier now than they were a generation ago proves that genes aren't the whole story. It's the changes in our environment that have made the biggest difference, Wyatt says.

A genetic predisposition toward obesity will only come into play when the environment is right. Getting obese was unlikely when our ancestors were eking out an existence on the savannah. But when we live in a society of sedentary jobs, sedentary entertainment, and cheap, plentiful and colossally caloric meals available at countless locations near you, that genetic predisposition can make a big difference.

How Do Medications Help?

The two drugs currently approved by the FDA to treat long-term obesity are Xenical and Meridia. They work in different ways. Meridia affects certain chemicals in the brain and makes people feel full without eating as much.

Xenical works very differently. It isn't absorbed by the system. Instead, it binds to fat cells in the gastrointestinal tract and prevents them from being absorbed, just like the ingredient Olestra used in some low-fat foods. The usual dose can reduce the amount of fat that's absorbed by about 30%.

The FDA has approved the use of weight loss drugs in people with a BMI of 30 or as low as 27 in some people who have illnesses related to obesity, like diabetes or heart disease. The BMI is a measurement based on height and weight. According to the National Institutes of Health, a normal BMI ranges from 18.5 to 24.9, 25-29.9 is overweight, and anything above that is obese.

Other drugs may be helpful in some cases. For instance, Wyatt has had good success with the generic drug phentermine, which suppresses appetite like Meridia. However, the FDA has not approved phentermine for long-term use. That's not because it was found unsafe -- it's just that no one has funded a study of its long-term effectiveness. And because studies are expensive, no pharmaceutical company will want to spend the money testing a generic drug that it doesn't exclusively own.

Modest Results

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.


"Being cautious about any weight loss drug is good policy. None of these drugs have been around that long."

"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.

Are They Safe?

One of the biggest concerns for anyone considering a weight loss drug is its safety. The fear is understandable. The much-touted combination of weight loss drugs called fen-phen -- phentermine and another drug, fenfluramine -- was found to cause dangerous damage to the heart valves in some people. As a result, both fenfluramine and Redux, another similar weight loss drug, were pulled from the shelves in 1997. On its own, phentermine is considered safe and still used.

Being cautious about any weight loss drug is good policy. None of these drugs have been around that long, and so we can't be sure of their long-term effects.

That said, the safety records for both Xenical and Meridia are good and the risk of side effects are low. Meridia can cause headaches, dry mouth, and a rise in the pulse and blood pressure.

Xenical can cause gastrointestinal side effects, such as spotting, an urgent need to go to the bathroom, and an increased number of bowel movements. These side effects tend to fade over time, and are aggravated by eating a high-fat meal. Xenical can also reduce the amount of vitamins that your body absorbs, so you may need to take a multivitamin to compensate.