Although I seem to be something of a lone voice here, I'm really struggling with this thread.
For one thing, there's the banality of stating your limited experience as factual information about "The Past". So "you didn't eat between meals unless it was an apple" is a manifestly ridiculous thing to claim.
And then there's this sort of "othering" that's going on - the claims that "people nowadays" are all going from Greggs to McDonalds and then home to start guzzling again, as if the poster in question somehow isn't a member of "people nowadays" 
And how can anyone claim we've lost sight of "normal"? "Normal" is literally what is normal at any given point. Normal is different now.
Average size was undoubtedly smaller decades ago. And of course the rise in obesity is bad news.
But there are plenty of people today (me and my family included) who are a healthy weight. We don't have the sort of appetite that, even with all the stuff available today, would lead to huge weight gain (barring unforeseen medical issues). We do expect to feel hungry at mealtimes, despite some posters suggesting people somehow don't do that anymore.
I don't like the judgemental tone and the constant suggestion that these hordes of thin people in The Past were somehow superior. I'll say it again - this is the sort of thinking that brought us Brexit.