@sunsetchaos her body put on weight thinking it had to gain excess reserves of energy to support a pregnancy- i think, i don't know much about false pregnancy(let alone actual pregnancies) but it seems like the most logical reason to me, unless actual pregnancies are just expanding due to the baby growing inside alone. but ive heard about weird food cravings and stuff, and a baby is literally a parasite leeching resources off of it's mother so it makes sense that the mom would then compensate for the demand by getting fatter.