Elven girls with super strong arms who can pull back the bowstring on legendary magical weapons turned into butterballs with arms so weak and fat that their bingo wings hang down to their hips and they can't raise their arms without their caretakers' help
And when they get a checkup at the human doctor specializing in elf girls, she gets told that's perfectly normal for healthy elf girls like her, but that she's concerned she's not getting enough butter in her diet (one of the main food groups for elves!) and prescribes her some appetite stimulants just to be safe
One of the older elven matrons who's still managed to stay skinny by resisting ever trying fast food, after seeing what it's doing to her people
Trying to teach the old ways of archery and magical spellcraft to the second generation of young elf women after first contact with humanity
And they're all already 250 lbs or more, chubby and getting chubbier every day, eating junk food snacks and slacking off on training and they can barely sustain a magical connection with the most powerful sylphwood trees for even a few seconds because they can't meditate without intrusive thoughts about food
Human corporations sending shipments of "free" fast food, butter, sugar, packaged foods, stretchy elastic clothes, soda, massage pads, and all sorts of other unhealthy comforts to all the elven enclaves in their realm as a token of human "generosity"
The elf girls digging into one free sample delivery after another, excited about how kind and generous their new human allies are! Not realizing that all the corporations are looking forward to turning every elf girl into addicted, dim-witted consumers with "jobs" as mana batteries or milkers to pay for all the buckets and buckets of fried junk they stuff themselves with every day ^-^
Fast food chains offering special reward programs for elves, where their first 5 supersized meals are free
Because studies have shown that's how many stuffings of junk food it takes to basically "ruin" an elf girl's taste buds, making her usual diet of berries and salads and bark herbs taste like dirt to her because she craves more butter and sugar so badly
The elven enclaves' academies send scholars on exchange to human universities and none of them come back, because they all end up forgetting about their research studies and becoming overfed fat girls waddling around campus with their human feeder girlfriends
One of the elven High Queen's daughters gets sent as the first ambassador to the human race for a year, along with an entire platoon of royal guards, maidservants, and advisors; the human delegation graciously assigns all of them personal assistants whose job is to "attend to their every need" as they adjust to the human world
When the Queen comes to visit Earth at the end of the year, she's shocked to see the princess and her entire retinue of guards, maids, and advisors all being rolled out in triple-wide wheelchairs, their human caretakers wiping dribbles of butter off their chins and giving them quick tummy rubs to squeeze out little burps and make sure they're "presentable" for their visiting guests
