The United States typically falls around 15th or 16th when it comes to obesity or BMI rates. For children, the United States ranks 148th - nearly at the bottom. America doesn't even meet the minimum to sustain a population without immigration (Birth rate in America is 1.87 and population replacement is 2.1).
Sources:
https://www.cia.gov/library/publicat.../2054rank.html
https://www.nationmaster.com/country...ple/Birth-rate
https://en.wikipedia.org/wiki/List_o...fertility_rate
https://www.worldatlas.com/articles/...the-world.html
https://www.oecd.org/els/health-syst...pdate-2017.pdf
https://en.wikipedia.org/wiki/List_o...ody_mass_index