Keeping It Off

Most people who successfully lose weight have a hard time keeping off the pounds. In fact, 85 percent of the obese people who lose weight wind up gaining it back. Now researchers at Columbia University Medical Center may have figured out why. The Early Show medical correspondent Dr. Emily Senay has details.

Our bodies conspire against us, because so many millions of years of evolution teach us that we should consume when food is available. So all the chemicals and hormones in our body are working against us to see that we do maintain a body weight, because we may go through a time when there isn't enough food.

Now scientists are starting to tease out what hormones and what parts of the brain and what parts of the body are involved in the mechanism that wants us to keep weight on our body. One of the hormones that they're really starting to take a look at is leptin.

Leptin was discovered in the '90s. They found in animal models that it helped animals lose weight but hasn't helped humans lose weight. Now they think they have a way to use it.

Leptin is a hormone made by fat cells. Researchers have found that when overweight people lose weight, their leptin levels go down. And it is the leptin that is there that tells you to expend energy. It helps reduce hunger.

Researchers had a group of volunteers lose about 10 percent of their body weight. They meanured their leptin before weight loss, then after the weight loss. Then, using daily injections, they were able to restore the leptin and found that, metabolically, they came to the pre-weight-loss level but didn't gain the weight back. (Results were published by the Journal of Clinical Investigation.)

Does that mean that we should all be asking our doctors for these leptin injections?

Not yet.

Senay explains that this was basically a demonstration that leptin can, in this setting, not help you lose weight, but possibly help maintain weight loss because it works metabolically in a particular way. There is a huge leap between this type of study and making it on the market. But it does open the door to a new way of thinking about developing drugs for weight loss.

"For examples," says Senay, "what do we now with weight loss medications? We have an unnaturally suppressed appetite or revved up metabolism. If we could naturally change the way our bodies are…functioning, it might be a lot better and easier for people."

But, obviously, there's a lot more research that needs to be done. In the meantime, there's only one way to keep weight off: Get a lot of exercise and eat well.