>>60251
>>60254
Okay. For starters this prompt doesn't even really take advantage of its own setting, so if I were writing this I would consider the inherent implications of humanity being capable of deep space travel in this world. The way I see it, it'd be the people up in space who'd be the first to fall victim to the epidemic.
Consider the fact that space is a zero gravity environment, so anyone in a ship or station is going to be experiencing a sense of weightlessness. This immediately eliminates the encumberment factor of being obese, if gravity isn't affecting you then your actual body weight is almost a non-factor. Ergo if people don't feel physically burdened by being fat then a lot of the negative stigma around it completely erodes and the fatties themselves will cease to care about their body health for the most part.
Space itself is also a limiting environment, even if you're on a gigantic ship its still a restctrive and confined area. The surronding space will just be a black void of nothing, it's not like on Earth where you can just drive off to somewhere else on the weekened if you get bored of being at home. So, people living in that sort of environment for extended periods of time would get bored of the repetiton over time and may end up being inclined to living more sedantry, less active lifestyles as they tire of exploring the same corridors over and over again.
That's a long-winded explanation of various factors that could lead to people in space getting fat. Now here's a very quick and dirty story outline that takes into consideration those ideas with the scenario anon suggested:
Humanity achieves inter-galaxy travel, sends an astronaut team into space. Astronaut team begin to passively gain weight and become nonchalant to getting fatter due to the factors I mentioned earlier. Simultaneous to this they're all unwittingly infected with a space-born pathogen that aggravates their appetites. Obese atronauts return to Earth, hailed as heroes. As they get in contact with people the pathogen begins to spread from person to person, a combination of the pathogen's physical effects and the astronaut team's influence on society and pop culture is what leads to the obesity epidemic.
Through seeing these fat astronauts in the media, people's negative thoughts and opinions on obesity begin to shift to the other direction. The pathogen's physical effects works in tandem with this societal shift and influences people to eat more. Entire population of Earth gradually becomes obese yadda yadda, eventually fatties begin clamouring to board commercial spaceflights so they can be as fat as they want without having to worry about being encumbered. The only people who end up remaining on Earth are those who already reached immobility and are therefore incapable of boarding a spaceship, those people get bigger ad infinitum and Earth becomes a wasteland full of helpless blobs.
Very long-winded, but there you go. Its an extrapolation of anon's idea but taking into consideration the context of the setting. Not claiming to be Shakespeare here, but I think it's much more interesting than "People eat pink food infected by living sugar and get fat." , whilst still being an easy to understand concept.