It appears that the obesity rate in the UK is about 30%, whereas in the US it's around 40%. For historical context, it seems that the US was at about 30% roughly around 2000.

So I guess that the US is fatter, but the UK is still one of the fattest countries in the world. The BBC claims the UK is getting fatter faster than the US too.

https://www.bbc.com/news/uk-41953530

http://www.oecd.org/unitedkingdom/Health-at-a-Glance-2017-Ke...

Teeth are probably a myth. People see Americans on TV, of course they do extreme things to make them blindingly white.