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Weight Loss With Medication

There's no magic bullet yet -- but for people with obesity, weight loss drugs can be a helpful part of treatment.

The Causes of Obesity

At the most basic level, your weight is determined by the balance between the amount of energy you take in and the amount you expend -- the food you eat and the calories you burn. If you burn more calories than you eat, you'll lose weight; if you eat more than you burn, you'll gain.

However, while that equation is still roughly true, researchers have found that it's a lot more complicated. The body has many complex and interacting mechanisms that help regulate your weight.

One of them is the hormone leptin, which is secreted by fat cells. Your brain detects the amount of leptin in your system and uses it as a kind of barometer. Not enough leptin presumably means that you need more food; enough leptin is a sign that you've eaten as much as you need, and your brain triggers feelings of fullness. The problem is that many obese people are leptin-resistant. Their brains don't correctly detect the amount of leptin in the system, "thinking" that the level is lower than it really is. As a result, a leptin-resistant person will keep feeling hungry after a person with normal leptin levels would feel full.

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.

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