I don't know if there is more prejudice than anywhere else, but certainly the Japanese seem more upfront about it. I wasn't overweight there but I was quite surprised by otherwise polite Japanese men AND women making very making very blatant comments about my body type while I was there. They were being complimentary but it was totally inappropriate stuff. Another blonde haired friend complained men would try to touch her hair in public. An old Japanese woman in a Japanese bath pointed at me and my bits and was talking, I think it was a compliment but... People will stare. You know I doubt they'd do this with other Japanese, but with gaijin it seems their normal politeness evaporates in this regard. It'd be worse outside Tokyo too. A lot of Japanese have very stereotypical ideas about westerners, particularly Americans.

I can say the prejudice may make it harder to get a job. You know if they have a young, slim person versus an older, obese person with otherwise the same qualifications, they're going to pick the young slim one. It's just how it is there. And photos on resumes are commonplace. BTW "old" is over 30.

But I saw overweight foreigners teaching English in Japan, so don't let it stop you. It's also very easy to eat healthily over there when you're surrounded by sushi places and restaurants serving miso soup for lunch.

And 25 years of teaching experience can be a disadvantage with the conversational English schools - they want teachers who can facilitate English conversation rather than "teach" it. The Japanese have had enough of grammar classes in high school. I imagine they'd be less discrimination in a college setting than in the private, for profit, English conversation schools too.