A new study, conducted by Stephen O'Rahilly of the University of Cambridge, England, suggests leptin, a natural hormone involved in the control of body weight, could potentially benefit many overweight people by helping them to shave off some pounds.
Previous research directed towards leptin treatment suggested that this hormone would only work with patients that lacked any leptin in their body at all. This study claims that the treatment is still effective even with people who have some leptin in their body.
"People have been saying it doesn't matter how much leptin you have as long as you have a smidgen. Our research suggests that it does matter,'' said O'Rahilly.
The research was not conducted as a treatment study, instead O'Rahilly investigated a group of patients who, due to a genetic mutation, had only about half the normal levels of leptin. O'Rahilly's team discovered that three-quarters of these patients were obese, compared with only one-quarter of the control group, thus showing that leptin levels are related to obesity.
Leptin is a natural hormone produced by the body and is believed to be involved in the regulation of body fat. Discovered in 1994, the hormone is thought to be produced by fat cells and is involved in the regulation of the fat to energy requirement ratio of the body.
In mice studies, increased levels of leptin caused the mouse's brain to believe it had plentiful fat supplies and resulted in decreased appetite and increased activity. Conversely, low leptin levels caused the mice to believe they had low fat reserves and resulted in increased eating and decreased activity.
Previously, it was known that individuals who produced no leptin had vigorous appetites, resulting in morbid obesity.
"The new research offers convincing evidence that people who have leptin at lower than normal levels are also prone to obesity," said Dr. Steven B. Heymsfield of St. Luke's-Roosevelt Hospital in New York, who was not involved in the study.
This study claims that individuals who have only small amounts of leptin are subject to some of the same effects, just with a lesser degree of severity.
"The newness of this is that there are partial forms of this condition. It's not an all or nothing situation,'' Heymsfield said.
While it is not clear how many obese people are actually afflicted with low leptin levels, one study places the number as high as 25 percent.
Heymsfeild's research into leptin therepy has produced mixed results, but he claims that a quarter of obsess people are leptin deficient and could benefit from the hormone therepyl
O'Rahilly's study was conducted on a fairly small sample group of 13 people. While it shows remarkable similarity to the mouse model, it fails to conclusively demonstate that leptin levels may help the broader community of overweight people, due to its tiny sample size.
"The trouble is they're trying to generalize from this relatively small group to suggest that many overweight people with low circulating leptin levels could be treated with leptin. It's a leap,'' said Tim Moran, a professor of psychiatry at The Johns Hopkins University.
Dr. Rudy Leibel, an obesity expert at Columbia University has also conduced leptin-related research, and said that he was intrigued that some of the people in the study's control group did not have genetic mutations yet were obese and had low leptin levels. Leibel said that suggests there may be as yet unknown problems with their leptin genes or their body's ability to produce leptin. Individuals with such problems might be predisposed to become obese and might benefit from leptin therapy, he said.
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