ILuvChubbyChix:
While this isn't really happening in an explicit sense (in that everyone is literally trying to fatten you up), in a way it's already happening as it is. There is no explicit, widespread encouragement but it's pretty much nearly normal and will be, very soon.
If current trends continue, and there's little to no reason to think it won't at this time, in '30 the American obesity rate is expected to reach over 50% amongst all adults. In some demographic groups, it's already over 50%. The OP is in New Zealand, but I have reason to think this is happening in most developed countries and many developing countries as well. However, I can only really speak authoritatively about the U.S.
Child obesity also continues to rise, and fat kids are more likely to become, and remain fat adults.
Here's a few things I heard of, trends, and observations I've made.
New York City, as well as any large city with a train, subway, or tram system occasionally has to repair or upgrade the equipment. A few years ago, when they last ordered new ones, they ordered seats that are wider. Clearly, they are expecting most riders to be heavier and have larger butts and will for the entire service life of the new train cars. As this is at great expense, I have no doubt this was considered carefully.
Let's look at new cars vs. older ones. The front bench seat is almost all but gone, in favor of bucket seats that are often such that you can't have 3 in the front. The back seat usually still includes 3 sets of seat belts, but I almost never see anyone use the middle seat, ever. Even one passenger in the back seat is pretty rare.
No one likes the middle seat, and it onyl gets worse when on average, everyone is wider.
On this note, consider booth seats in restaurants too. I almost never see 3 in a side anymore, only 2 tops.
I can almost swear portion sizes in restaurants are often larger too. You see advertised serving sizes when you look at a nutrition facts label, but ever notice how they rarely match up with what folks actually eat? Some manufacturers have started to include information about the entire bottle or package, but most haven't. A lot of times folks may also just go ahead and provide larger portion sizes for other folks too.
If sufficiently thin enough, some folks might comment.
As recently as a little over a decade ago, I never saw plus-size mannequins in stores. Now I see them all of the time. Some brands have had to increase the range of sizes they offer, so Lane Bryant and Torrid have competition they didn't use to have, at least for the female US size 12-20 range. In some places like Target or Wal-Mart, there's marketing materials about how any size is good, but others just offer them just because. Some brands haven't seemed to have gotten the memo, but it's only a matter of time until they do. They can either face a declining market every year as everyone gets fatter and there's literally fewer potential customers, or offer the extended sizes.
At this point, if you're really skinny you're the one who's more likely to stick out.
I'm sure most users of this web site have likely, at one point or another watched "What's Eating Gilbert Grape?" which was released in '93. It was in rural town, somewhere in Iowa of all places, I think it was. One of the scenes near the end involved his supposedly morbidly obese mother who was fat shamed when she left the police station, after demanding they release her younger son.
Thing is, if you see that scene again, you would see that while she would still be larger than most folks, folks of that size are just common enough nowadays that almost no one even talks about it anymore.
Anyway, my overall broad point is that it's either the point where it's actually normal, or it's pretty close.
However, there will still be some demographics that won't have a 50% obesity rate. However, broadly speaking it's more and more acceptable everywhere.
Ya, it people being fat might be better in the future, but...
1. I want it now
2. It could also be the case that people keep thinking that fat shaming is good, and so while being obese is normal, it could still be shameful.