I just went into Black-briar manor to deliver some ingredients to Ingun around 7 PM and found the entire family at the dinner table eating. Shortly after I left, at 8 PM Maven heads over to the Bee and Barb for another meal. I assume this is her regular schedule, two meals, one right after the other. So why isn't she the fatest person in Riften?

It could be light meals and she walks a lot around town that girl knows how to keep her figure.