My e-mail is backed up and haven't read yours yet, but hey how can I mind an e-mail? If someone takes the time to send an e-mail, it's a compliment!
Well - from Larger-Lois' POV, she already knew that the other Lois was slim. That's one of the reasons she wanted to meet her - to see a "thin" version of herself. I think it was weighing on her mind (pardon the pun), so she naturally brought it up. PLus, she probably knew that Thin-Lois thought that Alt-Lois would be an exact double of her, so she was self-conscious about being heavier than her.
The two women are going to have coffee. I'm sure you'll see more warmth during that conversation!