People with good self-control may make the worst food choices, says a new study. Those who score high in willpower, as measured by a questionnaire, will pick somewhat healthy foods from a list of so-so ones (a baked potato instead of fries or chicken nuggets). But when you add a truly healthy option, like a salad, they choose the fries. Why? It's called vicarious goal fulfillment. The mere presence of a healthy choice makes them feel good, causing them to let down their guard.