My thoughts about Qnexa, and obesity medications in general, derive in part from 2 classic Nobel prize–winning publications from the 1970s. In 1970, George Akerlof wrote about the market for bad cars, otherwise known as “lemons” (2). Suppose used car buyers have reason to believe that 75% of cars are good and 25% are lemons; buyers know that some owners want to sell their cars because they've discovered many problems. A good car, which we'll call “a peach,” is worth $20 000, a lemon only $5000. A prospective buyer has a big problem in being unable to distinguish peaches from lemons, whereas owners have no trustworthy way to communicate their inside knowledge. The buyer's problem, which Akerlof referred to as information asymmetry, leads to a low offer of, say, $16 250. Owners of peaches will refuse “low-ball” offers of less than $20 000, whereas sellers of lemons will gladly accept. However, the buyer will wonder why an owner would accept a low offer for a peach, suspecting that the car is in fact a lemon. The buyer will revise his or her offer down, say, to $12 500, making owners of peaches even less willing to sell. Over time, the only cars that will sell will be lemons—peaches will be driven out of the market. Because of information asymmetry, Akerlof argued, bad products drive out good ones.