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

Leptin is only one of many different mechanisms that regulate weight. Any kind of abnormality in these systems could make it harder for a person to lose weight and keep it off.

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.