On one day they were given no breakfast before the scans and on a different day they were fed a large, 730 calorie, breakfast an hour and a half before.
The idea is to "nudge" (Cass Sunstein's catchword) consumers into making healthy choices by either restricting unhealthy ones (Michael Bloomberg's proposed ban on large sodas), mandating disclosure of information (the ObamaCare provision mandating calorie counts on chain-restaurant menus), or mandating the manner of disclosure (for example, requiring a product advertised as "90% fat-free" to be reciprocally labeled "10% fat").