Sounds like bbw femdom, but with noodleboys and noodle girls.
Pics are basically BBW femdom with a focus on weight and contrast.
That said, the Molly and Nate stories fit this theme nicely. Molly is oblivious to how fat she is and keeps Nate on a restrictive diet while telling him he could stand to lose a few even though he's thin. Her logic is clearly incorrect, but realistic to how someone would act, like does she actually know and is tormenting him while playing dumb kinda way:
https://www.deviantart.com/mrtrazzorr/art/Molly-and-Nate-911746689
https://www.deviantart.com/mrtrazzorr/art/Molly-and-Nate-Part-2-912260583
https://www.deviantart.com/mrtrazzorr/art/Molly-and-Nate-on-Valentine-s-Day-952613433
https://www.deviantart.com/mrtrazzorr/art/Molly-and-Nate-Part-3-917271251
https://www.deviantart.com/mrtrazzorr/art/Molly-and-Nate-Part-4-945528444