Fat people claiming oppression is an insult to people who are actually oppressed.
Firm evidence is yet hard to find, but I think the best chance is that the Fat Acceptance/body positivity/fat celebration movement is mostly funded by food industry groups.
Why would they not do this? That’d have great return on investment. If I were Monsanto or General Mills or Nestlé I’d be shoveling money (discreetly) at these groups as fast as I could.
Some indirect evidence is that you never see any of these people or groups question current food industry practices, ask why obesity suddenly begin increasing in the 1980s and then skyrocketed in the early 1990s (even though processed foods had been widely available and cheap since the early 1950s), or make any effort into funding investigation into possible environmental exposure links to obesity.
Of course not. It all reeks of food lobby money. The ROI on that would be very high, so if they are not doing it I’d be extremely shocked.