This episode provides an overview of the significant challenge of dietary underreporting bias in nutrition research, especially concerning individuals with obesity. It explains how some people with higher body mass index (BMI) systematically and substantially under-report their true food and calorie consumption, often by 700 to 850 kcal per day, which is far more than their lean counterparts. The episode highlights that doubly labeled water (DLW) is the objective "gold standard" method for measuring actual calorie expenditure, and studies using DLW consistently validate the extent of this underreporting. This systematic inaccuracy, often driven by factors like social desirability bias, renders self-reported data from national surveys like NHANES largely unreliable for accurately assessing true calorie intake or its link to obesity trends. Ultimately, the episode cautions researchers to use objective measures and not rely solely on self-reported data when studying obesity.

Source on which the episode is based: