(Disclaimer, as I said in my post, I prefer fem stuff so most of the stories here are for female characters. But! If you are interested in including male characters and gains, I would be happy to think of and work something out with you!) 

Belle, due to proxy work being very sedentary but taking a lot of mental energy, alongside being next to so many good food options that are fast and easy, either always was fat (and getting fatter) or after a long line of commissions gets fat.

Fairy gets compromised/hacked/bugged, and decides it knows what's best for the proxies and their diets.

Cunning Hares have a very successful job and get huge from eating out all the time.

Cunning Hares take part in multiple eating competitions, maybe various food sponsors, or some other incentive for the girls to eat a bunch to make ends meet and get fat.

Grace makes a feeder robot that either does exactly what it says on the tin and is very effective, making our favorite Iron Witch into a one far softer. Or maybe it goes haywire, reaching a similar conclusion but with vastly different context.

Ellen tries some weird candy her friends got her that leaves her feeling quite funny and blue.

Rina, due to her questionable taste buds, decides to try some recipes she found on an quirky website that were intended to be jokes, but she downs them anyways. Consequences soon follow.

The life of Zhu Yuan is tough. Long hours of difficult work, and barely anytime to get some decent food and exercise in when you're she's off the clock and tired as hell. In fact, for this officer, it seems like she's going a bit soft from it all.

Some lifestyle changes to help fit in an undercover position is nothing special. But for Jane Doe? She'll go the exxxtra mile every time. So when she needs to investigate a notable culinary business while not seeming out of place, she'll happily fill the role.

Cheesetopia is booming in the Outer Ring! And for the current overlord and her posse, there's no other place they will go to get their fill. Whether it's a hardy platter of pancakes for breakfast, an array of sandwiches for lunch, or a platter of burgers and beer for dinner, these fiery bike riders eat each meal like it'll be their last.

Burnice has done it, with a new extra bubbly, extra fizzy, extra extra carbonated nitro-fueled cocktail. Just try not to drink too many, or you might get a little bloated.

The stress is really getting to a certain Yanagi, and it seems to be bringing out a new, possibly oni-related, side of her. One that stress eats more than Soukaku does on a good day. Now HAND has never been quiet, but especially now, you can hear the rumbles of something big whenever you're around section 6. 

I couldn't think of anything for Miyabi that wouldn't just be a different flavor of Yanagi's idea. So just imagine the scenario above but with tailess instead of oni blood. 

The life of a pop-star is undeniably fabulous. Full of incredible functions with truly divine eats. It can be challenging to walk the line, partaking of the goods offered but not indulging too much...especially if you're the Stars of Lyra.

Obol squad has very high expectations for its soldiers. Ones that, if they were to be taken on leave for a significant amount of time, could be hard to continue reaching. When you're working so hard, and are used to chowing down on a lot to keep that lifestyle up, taking the work out can be easy, but the appetite for that work can be much harder.

When you've got a master chef of a cook, a wonderful baker, and free meals for all time at some of the best spots in Waifei after saving the day, it can be easy to slip into some bad habits. Although surely the mystics of Yunkui Summit wouldn't fall for such obvious trappings right? Right?

For spook shack, tackling strange rumors and bizarre tales is what they do. And while most days don't bring much in the ways of real deal ghosts and supernatural happenings, some special days do bring some. Some that would fill the likes of Lucia and Yuzuha with absolute joy...among other things...