When consumers are diagnosed with a medical condition such as high cholesterol or obesity, they immediately begin a new regime of brisk walks and a diet of heart-healthy foods. Right? Not necessarily, says Wharton marketing professor Lisa E. Bolton . If those consumers are taking a prescription or over-the-counter drug for their condition, they may actually toss back more chips and donuts. Those taking a supplement, however, may be more likely to eat broccoli and hit the treadmill.

The reason, says Bolton, is that consumers see the drug as a “get-out-of-jail-free card,” which eliminates or reduces the risks of such bad habits as eating high-fat foods, excessive drinking or a sedentary life-style.…