Dietary Trends, Reporting Bias, and the Obesity Epidemic

This episode provides an extensive critique of the reliability of self-reported dietary surveillance data, arguing that simple correlations between dietary trends (like increased calories or changes in macronutrients) and the rise in U.S. obesity rates are misleading. The episode emphasizes that correlation does not equal causation and highlights the significant problem of systematic underreporting of calorie intake, particularly among individuals with higher body mass index. Furthermore, I assert that observed increases in reported calorie intake over time may actually reflect changes in survey methodology rather than real shifts in eating behavior. Finally, I note that despite increasing use of dietary supplements, most Americans still fail to meet recommended intakes for several key micronutrients, underscoring that overall dietary quality remains suboptimal.The studies on which this episode was based:Chery lD. Fryar, Jacqueline D. Wright, Mark S. Eberhardt, and Bruce A. Dye. Trends in nutrient intakes and chronic health conditions among mexican-american adults, a 25-year profile: United states, 1982–2006. Technical Report 50, National Center for Health Statistics, Hyattsville, MD, 2012. URL: https://www.cdc.gov/nchs/data/nhsr/nhsr050.pdf.Edward Archer, Gregory A. Hand, and Steven N. Blair. Validity of u.s. nutritional surveillance: National health and nutrition examination survey caloric energy intake data, 1971–2010. PLoS ONE, 8(10):e76632, 2013. doi:10.1371/journal.pone.0076632.Marjorie R. Freedman, Victor L. Fulgoni, and Harris R. Lieberman. Temporal changes in micronutrient intake among united states adults, NHANES 2003 through 2018: A cross-sectional study. The American Journal of Clinical Nutrition, 119(6):1309–1320, 2024. doi:10.1016/j.ajcnut.2024.02.007.Alexandra E. Cowan, Janet A. Tooze, Jaime J. Gahche, Heather A. Eicher-Miller, Patricia M. Guenther, Johanna T. Dwyer, Nancy Potischman, Anindya Bhadra, Raymond J. Carroll, and Regan L. Bailey. Trends in overall and micronutrient-containing dietary supplement use in us adults and children, NHANES 2007–2018. The Journal of Nutrition, 152(12):2789– 2801, 2022. doi:10.1093/jn/nxac168.