Researchers are learning more every day about how the body processes fat. One clue involves the hormone leptin, which is pumped out by fat cells and signals lab mice, at least, not to eat. Unfortunately, as reported last week in the Journal of the American Medical Association, it doesn't seem to work in humans. Researchers are still trying to figure out why not--and how to get around the problem. Another natural substance, called pro-opiomelanocortin (pomc), seems to signal that it's time to stop eating. Mice treated with pomc boosters shed 40% of their excess body weight in just two weeks. Again, it's not clear that this will work in humans, but it's conceivable that pomc therapy--perhaps in shots--could someday be standard.
Scientists are also focusing on the differences between two types of fat cells, known as brown and white. The former, active in young mammals (including humans), convert fat into heat rather than storing it. That's crucial in newborns, whose temperature-regulation systems aren't fully formed. As we age, the brown cells become inactive and the white, which convert dietary fat to body fat, take over. Several research teams have found that by reactivating the brown cells in an adult animal with medication, they can burn off fat dramatically. Now the doctors are looking for a genetic switch that can do the same for humans.
What's becoming clear to scientists in the obesity business is that the body's energy-processing system involves not one or two but a maze of metabolic pathways. pomc, leptin and brown fat cells are part of the story. But nerve cells have also been implicated in weight regulation, and it's not clear how these different pathways relate to one another. "Not a month goes by," says Dr. Eric Ravussin, director of endocrine research at Eli Lilly, "without publication of a new pathway that regulates feeding behavior, giving us new potential targets."
Untangling this metabolic mess will probably take decades. But given the immense profits waiting for whoever can invent a safe, effective weight-control substance, drug companies aren't waiting. With the clues they have in hand, pharmaceutical firms are now investigating about 60 compounds, most of them based on some of the 130 genes that have so far been implicated in weight control.
So it seems likely that for a while at least we'll keep getting fatter. We can't undo evolution, and we haven't found a way to fool Mother Nature--yet. But before the 21st century is half over, with the body's fat-centric metabolism laid bare and the ability to manipulate genes part of medicine's standard tool kit, the trend may finally stop. Chubbiness may not disappear, but it could become optional. A future without Richard Simmons' commercials would be a wonderful future indeed.
Reported by Alice Park/New York
PAGE 1 | 2 |
mystery
