It is a very effective method. It's common to do in Japan, and they have one of the lowest obesity rates of any first world country. No overbearing government regulations necessary.
The same can be said about most western Europe countries, yet they still have obesity rates above 20% compared to 4% in Japan.
https://en.wikipedia.org/wiki/List_of_countries_by_obesity_r...
>But do go on about fat shaming being effective.
It looks like the most likely explanation here.