Weighty issue. At least in some people, low leptin levels correlated with a high body mass
Once leptin seemed to be the ultimate fat-loss drug :. A hormone suppressing appetite which lack natural causes obesity. Boost blood levels of some of leptin, the researchers suspected of obesity, and they had to eat less. A clinical trial has vetoed the idea when obese people do not respond to treatment with leptin. But a new study shows that this can lead to low leptin chubbiness, suggesting that the hormone might help some people shed pounds.
In 1994, scientists discovered that mice missing both copies of the gene for leptin develop excessive body fat, extreme hunger, and infertility. Shortly thereafter, endocrinologist Stephen O'Rahilly of Addenbrooke's Hospital, Cambridge, U.K., identified two cousins with defects in both copies of their leptin genes. They produce virtually no leptin and show the characteristics of a mouse leptin deficiency. Parents of children are severely obese, even though each carried a defective and one normal copy of the leptin gene.
Now O'Rahilly and colleagues report that having a defective copy of the leptin gene does not affect the weight of a person, even if the effect is more subtle than people with two bad copies of the gene. The team found that people with one good copy of the gene have about half the normal hormone levels. Apparently, following the 13 people they studied end up heavier and packed with a significantly higher percentage of body fat than the family with two normal copies of the gene for leptin, the team reports in the November 1st issue of Nature . O'Rahilly said that in a separate unpublished study people with both leptin gene knockout match "extremely well" to the leptin therapy, although they have not tested people with just a bad copy of the gene.
"We now know that to have a little less than the normal amount of leptin is enough to cause a problem with body fat and weight," says obesity researcher Jeffrey Flier of Beth Israel Deaconess Medical Center in Boston. And with low leptin levels is a treatable disease. As O'Rahilly said, "There could be an obese subgroup with low levels of leptin equivalent, of which at least could be worthy of a clinical trial. "
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[1945019lapaged'accueil] Stephen O'Rahilly
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