General

Fat Doctor from the UK used to send bbw/bhm to meet ultra-sized counterparts in Evansville, Illinois as a 'wake up call' before returning across the Atlantic.
Philadelphia, PA and parts of Mississippi were named Fattest US City for brief moments.
Multiple entries from 600 lb life are in-state not traveling far to the doctor in Houston, Texas.

They are not public gainers/feedees though if you watch a few episodes, an experienced soul can sense tendencies in some of the people on both shows.

Nobody knows where the fattest states really are. It's not like someone asked people what they weigh. They use criteria like the proportion of fast food restaurants to gyms. They do not take into account how many people use the fast food places or gyms, what people eat, or how long they exercise. And they assume that people only get fat at fast food restaurants, and only get thin at gyms.

California seems to have the highest numbers of us in the USA.

But no one knows how many of us there are.