Low-Carb Diet Research and News

By Neil Sherman
HealthSCOUT Reporter

WEDNESDAY, Sept. 15 (HealthSCOUT) -- If you diet, you know the old saw that losing weight is a lot easier than keeping it off. But a new study suggests that injections of an appetite-control hormone may someday lead to a safe way to maintain weight loss.

Researchers gave the hormone, leptin, to a girl who was severely obese because she is one of the few people in the world who don't have it naturally. The girl lost weight, but the researchers say leptin's biggest promise is not so much dropping the pounds as keeping off those dropped pounds.

"This is the first time that we have conclusive proof that there is a genuine appetite regulatory hormone in humans," says Dr. Stephen O'Rahilly, a professor of metabolic medicine at Addenbrooke's Hospital in Cambridge, England. "While it is no magic bullet for weight loss, it has opened up new possibilities for a safe and effective appetite suppressant treatment, probably within the next five to 10 years."

O'Rahilly is a co-author of a study appearing in The New England Journal of Medicine.

O'Rahilly and his colleagues injected recombinant leptin to a 9-year-old girl. Terribly obese, she began putting on excessive weight from the age of 4 months on. When the therapy started, she carried 212 pounds on a 4-foot-7-inch frame.

"She is one of six people that we know of, worldwide, with a genetic leptin deficiency," O'Rahilly says. The young girl and her equally obese cousin were the first human beings identified as totally lacking in the hormone.

Leptin is the hormonal signal sent from fat cells to the hypothalamus (the part of the brain that regulates thirst, appetite, body temperature, and sleep) so that the body maintains appropriate levels of fat. Too little of the hormone makes you hungry, while normal levels tell your body that enough's enough.

Eating habits change

Within two weeks, the girl began losing weight and continued losing at an average of four to five pounds a month for one year. At the end of the leptin injections, the young girl's weight had fallen by 36 pounds.

More importantly, within seven days of the first injection, her eating behavior changed. She began eating less, no longer tried to sneak food and stopped demanding snacks. In addition, she began to show the first signs of puberty.

Leptin's evolutionary role is not weight loss but a way for the body to protect fat when it is faced with starvation, says Dr. Rudolph Leibel, co-director of the Naomi Berrie Diabetes Center at Columbia University In New York City and professor of pediatric medicine at the school. Leibel co-wrote an editorial accompanying the article.

"People already know that it is quite easy to get a patient to lose 20 or 30 percent of their body weight," Leibel says. "Yet 95 percent of them will regain that weight within two to four years. What we think, here, is that leptin will ultimately prove helpful in maintaining weight loss."

Leptin has achieved an almost cult status among obesity researchers and drug companies. "There are huge attempts to make the hormone into a drug," says O'Rahilly.

"We still have lots of questions about leptin," O'Rahilly says. "What we don't know is if you have some and we give you more, will it produce the same effect?"

What to Do

This important advance has only been shown in one patient and it may be five to 10 years before a pharmaceutical treatment comes to market. O'Rahilly says that researchers are now looking for where the hormone binds in the brain. "When we identify those molecules, we can use them to develop drugs."

For more information on leptin, and current clinical trials, see Amgen.

If you are trying to lose weight, see the U.S. Department of Agriculture's Food Pyramid for a balanced diet. This HealthSCOUT story on leptin can also provide you more information.