The Obesity Epidemic: Biology and Environment Explained

What has been corrected on this page?

Every accepted correction to this page is recorded with the exact change, so readers can see how the page improved over time.

1. 27 July 2026 · corrected by Emir Baycan

   Fact-check: corrected the NHANES obesity rate to 41.9% (2017-March 2020), fixed the Sumithran hormone count (9 not 12) and removed GLP-1 from the persistent-difference list, updated ultra-processed calorie share to ~53% (2021-2023), clarified the $173B CDC figure as direct medical costs, and corrected the Hall trial matching (presented calories) and Wegovy/Ozempic distinction.

   Before

   By 2020, U.S. adult obesity had reached 42%. ... Ten of the twelve measured hormones had changed ... GLP-1 was reduced. ... ultra-processed foods now account for approximately 57% of calories ... $173 billion (direct medical expenditures plus productivity losses) ... diets matched for total energy ... semaglutide sold under Ozempic and Wegovy.

   After

   Obesity reached 41.9% in the 2017-March 2020 NHANES prepandemic sample. The Sumithran study measured nine circulating hormones (not twelve), and GLP-1 was not among the persistent one-year differences. Ultra-processed foods provide ~53% of adult calories (2021-2023). The $173 billion CDC figure is direct medical costs (2019); productivity losses are separate ($13.4-26.8B, 2016). The Hall trial matched presented calories (intake differed). STEP 1 tested Wegovy (semaglutide 2.4mg), distinct from Ozempic.

   Why: Independent fact-check against CDC/NCHS, NEJM (Sumithran 2011), and Hall 2019: corrected an inflated/mislabeled obesity statistic, a wrong hormone count and GLP-1 attribution, an outdated ultra-processed-food figure, a conflated cost figure, an imprecise diet-matching claim, and a drug-brand conflation.

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2. 19 July 2026 · corrected by Emir Baycan

   Corrected the obesity-prevalence statistic on When Notes Fly's obesity epidemic explainer: the 42.4% figure was mislabeled as "as of 2020" when 2020 was only the publication year of the NHANES report; the actual measurement period was 2017-2018.

   Before

   As of 2020, 42.4% of American adults have obesity.

   After

   Based on the 2017-2018 NHANES survey cycle (published 2020), 42.4% of American adults have obesity.

   Why: The 42.4% obesity-prevalence figure was correctly cited from the CDC/NCHS NHANES data, but the article mislabeled it as "as of 2020" when 2020 was only the year the report was published. The actual measurement period was the 2017-2018 survey cycle. Fixed in the body (2 mentions), the excerpt, and the FAQ answer about why obesity increased since 1980.

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Who checked this page?

1 contributor has checked "The Obesity Epidemic: Biology and Environment Explained" on When Notes Fly. Each name below links to that person's public CitePep profile, where every contribution they have made is listed with the exact change they proposed.