For forty years, the CDC\’s National Health and Nutrition Examination Survey (NHANES) has collected data on the caloric intake of Americans, answering the simple and important question of how much food we eat. This research has in turn been used to instruct public health policy. NHANES is actually the basis for national standards of height, weight, and blood pressure, and its findings are often used to develop programs in the public battle against obesity.
But there\’s just one \”tiny\” problem. According to an analysis conducted by exercise scientist Edward Archer at the University of South Carolina, NHANES is very likely invalid. And it\’s for a simple reason that almost anybody could point out: All of the data it collects on caloric intake is self-reported.
Try to remember precisely what you ate over the past twenty-four hours and you\’ll see why this is a problem. People aren\’t only inept at estimating how many calories are in the foods they eat, they\’re also bad at recalling what they consumed and when.
With this in mind, Archer performed calculations merely to gauge if NHANES\’ data is physiologically plausible. In 1991, a team of physiologists determined that average, free-living individuals must consume at minimum at least 35% more calories than their basal metabolic rate (BMR) — the amount of calories they expend resting — in order to maintain their weight and health. This accounts for the energy people need to perform everyday activities, from just walking around, to playing sports, to gardening, etc. Archer used a well-established equation to estimate the BMR of individuals in the NHANES study, multiplied those values by 1.35, and compared them to the self-reported energy intakes in NHANES. What did that comparison yield? The majority of respondents, totaling 28,993 men and 34,369 women, reported eating less calories than even the bare minimum necessary to survive!