So I got bored while watching some Sci-fi movies and I thought of an idea for a sci-fi weight gain story. I sketched out a rough concept while I still had it in my mind and down below is the rough outline I got for said story:

-Man-made planet exists as a planetary resort
-Many who move there live a carefree life of luxury and excess
-Eventually a good amount of citizens began putting on weight and found that even though they hadn't gotten that big yet moving around was still a hassle, as well as didn't want to become lazy blobs floating around
-Planet founders create a special lift gear that's easy to use and restores all mobility, while hoping people will continue to use them and regularly bring their Lift Gear in for maintenance to make back the R&D expenses
-People begin using these and also find that its a good way to help them get back in shape but people begin using them less and less as the need is no longer there
-This ends up raising a financial problem for the planet as they already poured money into this device and if everything went well people would no longer need them
-Creators of the suit then release a brand new upgraded suit with various devices installed onto it and begin marketing it as a fashion statement
-A new trend wearing these full gears takes off but the developers worry that this might result in the same problem as before
-One person on the team accounted for this and installed a few special features into the gear
1)The audio and visual components of the gear would feed subliminal messages to the wearer to entice them to continue hedonistic behaviors
2)The large device on the back of the gear would occasionally release a special gel that was marketed as a way to keep comfort while wearing the gear, but in reality once the gel is absorbed through the skin it works to slow down the metabolism
3) Once a specific weight is reached, to keep the wearer from realizing something is wrong it would begin toying with their mind to make them appear and feel like they weigh less than they actually do
-As time goes by the planet's population begins to fill with obese citizens who are still able to move around to get to their next meal where ever it is

I hope to maybe refine the lift gear design a bit and who knows, maybe i'll turn this into a full story.

EDIT: Updated with more details on the gear