ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Monday, February 3, 1997 TAG: 9702030096
SECTION: NATIONAL/INTERNATIONAL PAGE: A-7 EDITION: METRO
DATELINE: NEW YORK
SOURCE: Associated Press
Bolstering hopes of one day developing an obesity drug, scientists have uncovered the first direct evidence that people with low levels of the hormone leptin may be prone to weight gain.
A study reported in the February issue of the journal Nature Medicine found that people who gained an average of 50 pounds over three years had started out with lower leptin levels than did people who didn't put on any weight.
While the study doesn't prove that low leptin levels lead to weight gain, it strongly suggests that, said one of the researchers, Eric Ravussin, a visiting scientist at the National Institute of Diabetes and Digestive and Kidney Diseases.
The finding supports the tantalizing idea that giving leptin might help some fat people slim down. Ravussin said some 10 percent of overweight people might be leptin-deficient.
Leptin made headlines in 1995 when scientists reported that it could melt weight off mice. It is made by fat cells and appears to tell the brain how much fat an animal is carrying.
The mouse brain is thought to have a leptin thermostat. If it senses a lot of leptin, which indicates a lot of fat, it tells the animal to eat less and be more active. If there's too little leptin, it signals the mouse to put on weight.
People have leptin in their blood, too, but it's not clear whether it affects their weight. Studies of injecting leptin into people have already begun.
Scientists launched the new study after noticing that some people have less leptin than would be expected from their degree of obesity.
Ravussin and colleagues turned to records from a long-running study of Pima Indians, who are prone to obesity. The researchers identified 19 men and women who had gained at least seven pounds a year and 17 whose weight had been stable.
Then the researchers retrieved frozen samples of blood the Indians had given about three years before and measured the levels of leptin they had at that time. On average, the weight-gainers started out with about one-third less leptin than the others.
The results are intriguing, said John Foreyt of the Baylor College of Medicine in Houston, who also has studied leptin in humans. But with so few participants, the study will have to be done again with larger numbers, and with people other than Pima Indians, he said.
Still, if further studies show similar findings, doctors one day may be able to identify children with low leptin levels and give them the hormone to help prevent them from getting fat, he said.
Foreyt said leptin isn't the only influence over a person's weight, nor would low levels necessarily mean a person will get fat. ``All of us are in control of our behavior,'' he said.
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