NHANES was used to collect data on the calorie intake of tens of thousands of people of varying health and fitness, starting in the 70s. The data would then be used to analyse trends and create advice to be used by government agencies advising the public. That means it's pretty important to make sure you get correct data so you can give reliable advice. Getting unreliable data means giving unreliable advice.
The results of the study show that the caloric intake for many of the people that have taken part in the study was massively under reported, by up to 800 calories a day in some cases. The study calculated things such as the basal metabolic rate for individuals and compared that to the calories reported to have been consumed. They found that some people wouldn't have even survived on the calorie intake they reported!
Some of you may be asking why we're talking about calorie intake in such detail when we don't believe calories to be as important as most people feel. Well it's not necessarily the caloric information that is concerning, it's what has been done with this caloric information. NHANES data has been used for the past 40 years to give advice to the general public on how to eat healthily and on the links between calories and health. The concern is that if the survey collected unreliable data then the health and fitness advice given to people about their calorie intake is unreliable.
Recommendations from the authors of the study include either erasing the incorrect data or even starting the survey again from scratch using more reliable collection methods. That's pretty drastic stuff so suffice to say their concerned bat the impacts of the incorrect data.
Recommendations from us are to once again focus more on the content of your meals and the quality of the ingredients you use rather than the calorie intake and you'll allow your body to work how it wants to work.