This new study says that the majority of the data can't possibly be accurate. Basically, people claimed they ate far less food than their physical checkup indicates they'd need. If an obese person with a very high body mass percentage--body mass and weight being empirical data which the subject can't lie about--reports that he or she consumes 1,500 calories a day, the study gives that person a high "disparity value," a new point of data that the NHANES had not calculated. An obese person may be able to survive on 1,500 calories a day, but that person won't be obese for long, which makes that calorie count unlikely to be true. En masse, if a huge number of people in a certain category (like, say, the obese) have a high disparity number, it's likely that something's wrong here.