Ugh. As a longtime vegetarian and a vegan wherever it's practical, I've faced the same situation in reverse more times than I can count. There was one guy in particular when I was in Japan who was, to put it politely, carrying quite a lot of extra weight, but who would continually lecture me on how I was being unhealthy and how I couldn't possibly be getting all the nutrients I needed. I guess maybe he was projecting his insecurities about his own dietary issues onto me? Really wish people wouldn't get preachy on either side, anyway, whether it's vegetarians / vegans lecturing meat eaters or the reverse. Particularly when it's people who are in no position themselves to be lecturing anyone on health.