Nah she gains weight, pay attention to her uniforms tie, the more she eats the higher its angle becomes as her breasts grow larger, and by larger i mean they pretty much triple, or more, in size after she digests 5 or 6 students, that and her ass gets massive enough to clip under the skirt. The only pred that i've noticed pretty much 0 weight gain from is the fairy, but thats only because her ass never starts clipping out of the weird space filling bs on the skirt.