Hello, I'm new to this board.

Me and my girlfriend have been recently thinkin' about going on a diet and workout plan, yet she's worried that her breasts and butt will shrink during the whole process.

Is this true and if so, are there ways to maintain the proper sizes? Thank you. :)

Oh, off topic, is there a way that I can change my log-in name?

It can be true. Breast tissue is surrounded by fat and when your body is burning fat, it tends to tap into breasts as well, although often to a lesser extent. Some women lose almost no breast size as they get leaner and some do; it's all determined by genetics. There is no way to prevent it and keep them to their "proper" size, but as the whole body gets leaner it will typically stay in proportion to the body. I really, really hope that isn't a significant deterrent to exercising and eating better. ;)