Did most of you comment before reading the rest of it or something? Sensei said the scale does seem off. We don't know her actual weight, just that 75 was too much.
For people thinking her weight is all in her breasts: just for reference: my girlfriend's were a large C/small D (American sizing), and post-mastectomy weight was less than 3 kilos.
So yeah, boobs don't weigh all that much comparatively speaking.