World's Fattest Cat Crumbs Dies Weeks After Feline Fat Camp

Crumbs, the world’s fattest cat, has sadly died just weeks after shedding some pounds at feline fat camp, with vets saying his excessively chunky layers hid cancerous tumors.

The Russian kitty -- who ballooned to a whopping 38 pounds from living in a hospital basement and munching on cookies and soup from the staff -- suddenly had breathing issues and passed away Saturday, according to NewsX.

Galiana More, who runs the Matroskin cat shelter where Crumbs was treated, explained his fat was so deep it hid cancerous tumors on his spleen and other internal organs, which they believed triggered multiple organs to collapse.

As of now, Crumbs' official cause of death hasn’t been determined yet, but More said it’ll be tough to figure out if he died from the tumors or his excess weight.

Crumbs -- who was so heavy he couldn’t even walk -- managed to lose 7 pounds at a special veterinary weight loss center in Perm, Russia ... and all his tests were normal in the weeks leading up to his death.