Zack's mom was a bit stocky, getting heavy as she edged towards her fifties and the trials of dealing with Zack and his four older siblings (all in college now) wearing on her. But she didn't notice his food had changed, or his hair. It seemed normal to her. Zack thought about that a moment, and then realized that that meant any changes he made people would believe had always been that way.
Just then he realized what he could do to turn this into the best birthday ever.