It's like doctor shopping/going to a different pharmacy when you're filling extra prescriptions if you're addicted to painkillers or what have you. It's just addict behavior and the shame cycles that go along with it.  Fats aren't special except to the extent that they demand (and to a disgusting degree, get) special treatment from society such that they receive less explicit shaming than other addicts who arguably aren't doing as much damage to the public as they are.