Leptin drew massive and immediate interest not just because of the surprise of where it was produced but even more because of what it does: it helps to regulate appetite. If we could control leptin, then presumably we could help people to control their weight. In studies with rats, scientists discovered that by manipulating leptin levels, they could make rats obese or lean, as they wished. This had the makings of a wonder drug. Clinical trials with humans were quickly undertaken, amid considerable anticipation.
