I believe the anecdotes I've seen were about people on this drug finding that they thought about formerly favorite unhealthy foods and viscerally recoiled at the idea of eating them.

My speculation is that it's a gut biota change driving the change in cravings, but I'm not sure there's much research on the mechanisms involved yet, since these drugs are very new, comparatively. A very small study apparently suggested it ameliorated some of the numbness to intense flavors that the obese have been shown to have in previous studies, so maybe I'm completely off base.